Introduction

When this article was first updated in April 2006, it discussed a number of AIX 5L™ features and functionality available as of that date, including the ones implemented in the 5300-03 technology level. This update includes some of the features implemented in the technology level 5300-05 which was released in August 2006. For the sake of completeness, I have retained the original content.

In the following discussions, I use the expressions AIX 5L Version 5.3 and Version 5.3 interchangeably and also use the expression (5300-05) to indicate that the referenced feature is available only for the 5300-05 technology level and beyond.

General observations

AIX 5L Version 5.3:

• Is binary compatible with AIX 5L Version 5.1 and 5.2.
• Runs on all currently supported CHRP (Common Hardware Reference Platform)-based POWER hardware.
• Doesn't run on Micro Channel or PReP (PowerPC Reference Platform)-based systems (as was the case with AIX 5L Version 5.2).
• Supports only the multiprocessor kernels -- both 32- and 64-bit.

AIX 5L Version 5.3 features and functionality

Hardware support

AIX 5L Version 5.3 supports the following POWER5 hardware features:

• Micro-Partitioning: Allows a single processor to be shared by up to 10 partitions and supports up to 254 such partitions.
• Virtual I/O: Supports the I/O needs of client partitions (AIX® and Linux®) without having to dedicate separate I/O slots for network connections and storage devices for each client partition. You can boot and run the partitions from Virtual SCSI devices and achieve network connections using the Virtual Ethernet and Shared Ethernet Adapter.
• Virtual SCSI: Reduces the need for dedicated physical disk resources for client partitions.
• Virtual Ethernet: Supports in-memory network connections between partitions and reduces or eliminates the need for separate physical Ethernet adapters, except for external connections. Security of partition-to-partition communications is guaranteed by unique VLAN configurations.
• Shared Ethernet: Reduces the need for physical Ethernet adapters by providing a way to move network traffic outside the server by routing it through a software-based layer 2 switch running in the I/O Server partition.
• Shared Ethernet Adapter (SEA) Failover: Provides Shared Ethernet Adapter High Availability by offering the ability to create a backup SEA on a different Virtual I/O server that will bridge, should the primary SEA become inactive.
• SMT: Version 5.3 supports the SMT mode of POWER5 processors. When you enable this mode, a single physical POWER5 processor appears to the operating system to be two logical processors, independent of the partition type. A partition with one dedicated processor would behave as a logical 2-way by default. A shared partition with two virtual processors would behave as a logical 4-way by default. You can turn the mode on or off for a specific partition either immediately or on a subsequent boot of the system.
• Integrated Virtualization Manager: Provides logical partitioning support without an HMC by integrating functionality into the Virtual I/O Server partition. Supports entry System p™ and OpenPower™ servers with SF235 firmware. All I/O is virtualized using the IBM Virtual I/O Server. Provides a subset of the HMC service functionality and a Web-based interface with seamless integration of LPAR and virtual I/O management.

Application development

• POSIX (Portable Operating System Interface) real-time compliant functions
  Version 5.3 provides system interfaces for the following POSIX real-time options:
  • Memlock
  • Spin lock
  • Clocks
  • Thread options
  • Barriers
  • Priority scheduling
  • Prioritized I/O
  • Message passing
  • Semaphores
  • Timers
  • Advisory information
• Perl 5.8.2, the latest version of the code, is shipped with AIX 5L Version 5.3. It contains fixes for bugs in Perl 5.8.0.
• Increased inter-process communication (IPC) limits
  In AIX, the individual IPC data structures are allocated and deallocated as needed, so memory requirements depend on the current system usage. Prior AIX releases defined the maximum number of semaphore IDs, shared memory segment IDs, and message queue IDs to be 131072 (128 K) for the 64-bit kernel. To cope with anticipated future scalability demands, AIX 5L Version 5.3 increases the maximum number of data structures for each of the IPC identifier types to 1048576 (1024 K).
• Cryptographic sum command
  Users often use the sum command to generate a checksum to verify the integrity of a file. However, it's possible that two distinct files will generate the same checksum. A cryptographic sum command, csum, has been implemented in AIX 5L Version 5.3, which offers a more reliable tool to verify the integrity of a file. The csum command aids in the AIX e-fix upgrade process, by offering users a mechanism to verify that a file has not been tampered with or corrupted during download.
• Java™ 1.4.2
  Both 32-bit and 64-bit versions of Java 1.4.2 are shipped with all new orders of AIX 5L Version 5.3.
• Thread support in gmon.out
  When applications consisting of multiple steps in which different executables (all built with -p or -pg flags to generate profiling information) are invoked in a sequence, each executable causes the previous gmon.out file to be overwritten. In AIX 5L Version 5.3, the gmon.out file has been made thread-safe so that each thread from a multi-threaded application has its data in it.
• gprof thread support
  AIX 5L Version 5.3 provides thread support for gprof. This enhancement aims at adding new functionality to gprof so that it can interpret additional information available for thread-level profiled programs.
• gprof support for large applications
  The gprof application profiling tool can now handle very large applications containing more than 32 million symbols.
• Enhanced libc.a
  AIX 5L Version 5.3 has implemented a number of new APIs for the libc.a library. Updates to a number of existing functions in this library provide improved system performance, reliability, and serviceability for the Identification and Authentication services provided by this library.
• New malloc() algorithm
  A new malloc subsystem called Watson Malloc has been implemented in AIX 5L Version 5.3. Watson Malloc provides improvement over the default implementation (Yorktown) in the area of memory fragmentation and performance for multi-threaded applications. Watson Allocator handles small requests quickly and with comparatively little wasted memory.
• Improvements to the malloc subsystem
  The number of malloc-related environment variables supported by AIX 5L Version 5.3 has been reduced to three and the attributes they can assume have been redefined. These environment variables are: MALLOCTYPE, MALLOCOPTIONS, and MALLOCDEBUG. MALLOCOPTIONS is a new environment variable that takes care of all current and future options to the MALLOCTYPE allocators. It supplants the MALLOCBUCKETS, MALLOCMULTIHEAP, and MALLOCDISCLAIM, which have been deprecated.

  Malloc log and Malloc trace functionality have also been enhanced.

  All malloc debugging options, which produce printed output, send their output to stderr. The new "output" debugging option provides a mechanism to instruct the subsystem to send printed output to a different file stream.

  Many malloc debugging options call the abort() procedure when they encounter an error. It is often the case, however, that a developer might wish to debug other classes of errors first and would prefer that less serious errors do not produce fatal flaws. The new "continue" debug option offers this choice.

• Enhancements in performance-sensitive xmalloc debug (XMDBG) (5300-05).
• DBX malloc command
  Malloc debugging features have been integrated into DBX command. This would allow a developer to query the current state of the malloc subsystem without having to create complex, unwieldy scripts requiring internal knowledge of the malloc subsystem.
• Enhanced DBX functionality
  Major enhancements have been made to DBX in AIX 5L Version 5.3. The following is a list of some of them:
  • Users now have additional control over the way DBX uses debug events. Should a user need to disable the effects of a debug event, DBX currently requires that the event be completely removed. In a scenario where an event must be repeatedly removed and added, a user must manually reenter the event each time it's to be enabled. This inconvenience has been removed with the addition of two new DBX subcommands: disable and enable. These subcommands allow the DBX user to temporarily disable debug events without permanently removing them.
  • Currently, if any dependent module referenced by a corefile is not available at debug time, DBX displays the fatal error "cannot open <dependent module path>" and exits. This behavior prevents debugging of the corefile from occurring until all of the dependent modules are located. DBX now allows the debug session to continue even if a number of dependent modules referenced by the corefile are unreadable or missing. A notification message, including the name of the missing module, is displayed by DBX during initialization for each missing dependent module. DBX also sends notification messages if any dependent module referenced in the corefile is found to be different from what it was at core file creation.
  • Several new subcommands have been added to DBX. These include proc, kthread, and fd. The purpose of these subcommands is to display data contained within the data structures used by the kernel to keep track of processes and threads.
  • To facilitate ease of debugging pthreaded code, the scope of DBX functionality has been enhanced by providing several new subcommands that reveal information about pthread objects and display them in a readable, user-friendly format. These include handler, onceblock, and resource subcommands.
  • The DBX functionality and usability have been enhanced by adding a subcommand, corefile, that displays information about a debuggee <corefile>. Without arguments, the corefile subcommand prints basic information about the <corefile>. With arguments, more detailed information can be requested.
  • Stack reading enhancements. With new 'frame' subcommand you can jump to specified frame number to show information. (5300-05)
  • New $stack_details variable which shows extended details of each stack frame. (5300-05)
  • Breakpoint command enhancements. You can associate commands with breakpoints; for example, you might want to always display stack when certain breakpoint is hit. (5300-05)
  • Deferred events support which allows events even if symbols are not present. (5300-05)
  • Regular expression symbol search. (5300-05)
  • Thread-level breakpoint and watchpoint support. (5300-05)
• The Eclipse Runtime Environment shipped with AIX 5L Version 5.3. This provides a platform on which Eclipse-based tools, including the new procmon performance monitoring tool (described under Performance management section), run.
• Unicode 4.0 support
  AIX 5L Version 5.3 includes enhancements to the existing Unicode locales in order to bring them up to compliance with the latest published version of the standard. This version adds additional characters and scripts to the standard, bringing the total number of defined Unicode characters to 96,382. Some of these characters are required to support the Japanese Industrial Standard JISX0213.
• tcpdump upgrade to latest level
  The tcpdump command has been upgraded to Version 3.8. As a consequence of this upgrade, iptrace and ipreport were also changed to use the new upgraded libcap library (Version 0.8) for packet capture and dump reading. AIX tcpdump, prior to AIX 5L Version 5.3, displayed packet timestamps down to 1ns (10^-9 s). The open source tcpdump displays timestamps at 10^-6s. The new AIX tcpdump has 10^-6s timestamp resolution.
  
  A number of new flags have been added to tcpdump. Also, a total of 87 protocol printers have been included to facilitate printing when using tcpdump.
• Multiple desktop selection from BOS install menus
  Prior to AIX 5L Version 5.3, you could choose only one of three desktops (CDE, GNOME, or KDE) during a BOS install. Starting with Version 5.3, multiple desktop selections from the BOS install menus are available. The available choices are CDE, GNOME, and KDE.
• Presentation of man pages has been improved by using sections and paragraphs.
• A new environment variable DR_MEM_PERCENT has been introduced. It is used to notify all DR (Dynamic Reconfiguration)-aware applications sharing an LPAR by what percentage-factor, instead of an absolute amount, their memory usage should be scaled down. This would help avoiding underutilization or overutilization of available memory resources.
• Named Shared Library Areas and increased 32-bit Shared Library Text Capacity
  A named shared library area enables a group of processes to have the full shared library capacity available to them at the same location in the effective address space as the global shared library area. Named Shared Library Areas also enable AIX to support an alternate memory model that dedicates both shared library segments (0xD, 0xF) to shared library text. This model is useful for groups of 32-bit processes, which share greater than 256MB of library text.
• LD_LIBRARY_PATH
  An alternative environment variable for runtime library path has been added for compatibility with SVR4-based systems. The system loader treats it as a synonym for the LIBPATH environment variable.
• Two new environment variables, LDR_PRELOAD (for 32-bit execution environment) and LDR_PRELOAD64 (for 64-bit execution environment), have been introduced. They allow users to preload symbols into an executable. They can be used to correct a faulty function without relinking. They are also useful for running alternate versions of functions, without replacing the original library. (5300-05)

Storage management

• Volume group pbuf pools
  In previous AIX releases, the pbuf pool was a system-wide resource. In AIX 5L Version 5.3, the Logical Volume Manager (LVM) assigns and manages one pbuf pool per volume group. Version 5.3 has introduced the lvmo command, which can be used to display pbuf and blocked I/O statistics as well as the settings for pbuf tunables.
• Scalable volume groups
  AIX 5L Version 5.3 offers a new volume group type called scalable volume group (VG). The scalable VG can accommodate a maximum of 1024 physical volumes and raises the limit for the number of logical volumes (LVs) to 4096. The maximum number of physical partitions (PPs) is no longer defined on a per disk basis, but applies to the entire VG. The scalable VG can hold up to 2,097,152 (2048 K) PPs. The range of the PP size starts at 1 MB and goes up to 131,072 (128 GB), which is more than two orders of magnitude above the 1024 (1 GB) maximum available in AIX 5L Version 5.2.
• Variable logical track group
  AIX 5L Version 5.2 accepted logical track group (LTG) values of 128 KB, 256 KB, 512 KB, and 1024 KB. To support larger sizes of many disks and better disk I/O performance, AIX 5L Version 5.3 accepts values of 128 KB, 256 KB, 512 KB, 1 MB, 2 MB, 4 MB, 8 MB, and 16 MB for the LTG size. Version 5.3 also allows the stripe size of an LV to be larger than the LTG size in use and extends support for stripe sizes for 2 MB, 4 MB, 8 MB, 16 MB, 32 MB, 64 MB, and 128 MB to complement the 4 KB, 8 KB, 16 KB, 32 KB, 64 KB, 128 KB, 256 KB, 512 KB, and 1 MB options available in prior releases of AIX.
• Striped column support for LVs
  In previous AIX releases, you could enlarge the size of a striped LV as long as enough PPs were available within the group of disks which defined the RAID disk array. Also, rebuilding the entire LV was the only way to expand a striped LV beyond the hard limits imposed by the disk capacities. To overcome the disadvantages of this rather time-consuming procedure, AIX 5L Version 5.3 introduces the concept of striped columns for LVs. In prior releases of AIX, it was not permitted to configure a striped LV with an upper bound larger than the stripe width. In Version 5.3, the upper bound can be a multiple of the stripe width. One set of disks, as determined by the stripe width, is considered as one striped column. If you use the extendlv command to extend a striped LV beyond the physical limits of the first striped column, an entire new set of disks will be used to fulfill the allocation request for additional logical partitions, as long as you stay within the upper bound limit. The -u flag of the chlv, extendlv, and mklvcopy commands now allow the upper bound to be a multiple of the stripe width.
• Performance improvement of LVM commands
  A large number of changes and enhancements have been implemented in AIX 5L Version 5.3 to reduce the execution times of the following LVM commands:
  • extendvg
  • importvg
  • mkvg
  • varyonvg
  • chlvcopy
  • mklvcopy
  • lslv
  • lspv
• Removal of classical concurrent mode support
  The support for classical concurrent mode VGs has been removed from AIX 5L Version 5.3. When trying to import a classical concurrent mode VG, an error message informs the system administrator to convert the VG to an enhanced concurrent mode capable VG.
• Disk quotas support for JFS2
  AIX 5L Version 5.3 extends the JFS2 functionality by implementing disk usage quotas to control usage of persistent storage.

  Disk quotas might be set for individual users or groups on a per file system basis.

  Version 5.3 also introduces the concept of Limit Classes. It allows the configuration of per file system limits, provides a method to remove old or stale quota records, and offers comprehensive support through dedicated SMIT panels. It also provides a method to define a set of hard and soft disk block and file allocation limits and the grace periods before the soft limit becomes enforced as the hard limit.

  The quota support for JFS2 and JFS can be used on the same system.

• Shrink a file system
  AIX 5L Version 5.3 supports shrinking a JFS2 file system. When the size of the file system is decreased, the LV on which the file system resides is also decreased.
• Rollback Function (available for JFS2 file system only)
  Restores an entire file system to a valid point-in-time snapshot (target snapshot). Rollback attempts to restore the snapshots present at the time of the target snapshot. Snapshots taken after the target snapshot are lost.
• Geographic Logical Volume Manager (GLVM). It extends the LVM mirroring function and supports an LV copy on a remote AIX system connected using TCP/IP network. Complete copy of application data can be quickly and easily brought back online on remote system.
• The mirscan command. This command searches for and corrects physical partitions that are stale or unable to perform I/O operations. This is useful for the following type of situations:
  1. A physical partition on the underlying storage is incapable of performing I/O operations, but for a long time no I/O operations have been attempted for that physical partition. The customer needs a way to detect and correct this condition.
  2. A disk is about to be replaced. The customer needs to make sure they are not about to remove the last good copy of their data from the system.
• Multiple Instances of AIX on a Single Root Volume Group (multibos)
  This feature allows the user to create a new instance of the AIX Base Operating System (BOS) within the running rootvg. This new instance, based on the running rootvg, contains private and shared data.
  A similar offering already available is Alternate Disk Installation. While somewhat similar, multibos varies in a few very important aspects:
  • The new instance is built from the running root volume group (similar to the alt_disk_install clone operation).
  • The new instance is housed within the current root volume group (for example, the same disks).
  • Certain data within the rootvg might be shared between the instances.

This feature has been made more robust and more user-friendly in 5300-05

Reliability, Availability, Serviceability (RAS)

• Error log hardening
  An error log might occasionally get corrupted when a system is terminated without stopping error logging. The current recovery strategy is to make a copy of the log and then reset the log as if it were a new log, rather than attempt to recover the existing log entries. AIX 5L Version 5.3 introduces a recovery method wherein the log is recovered when the errdemon is started. It checks for the error log consistency. If the errdemon detects a corrupted error log, it makes a backup copy of the existing error log file to /tmp/errlog.save and then repairs the existing log.
• System dump enhancements
  Dump information is displayed on the TTY during the creation of the system dump.

  Following a system crash, there exist scenarios where a system dump might crash or fail without one byte of data written out to the dump device. For cases where a failed dump doesn't include the dump minimal table, the failures cannot be easily diagnosed. In AIX 5L Version 5.3, the dump procedure is enhanced to use the NVRAM to store minimal dump information. In case the dump fails, you can use the sysdumpdev -vL command to discover the reason for the failure.

  A new option -c has been added to the dmpfmt command to verify the integrity of a dump.

  System dumps can now be copied to DVD media. You can also use DVD as a primary or secondary dump device. The snap command can use a DVD as source as well as an output device.

• Single thread trace
  In prior versions of AIX, system trace traced the entire system. The trace command in AIX 5L Version 5.3 is enhanced by new flags, which enable the trace to run only for specified processes, threads, or programs.
• Configuring large number of devices
  For each device configured in the system, an entry is made in the /dev directory. On systems with many devices, it's possible for the system to run out of space in the root file system or to run out of inodes. Prior versions of AIX did not report the cause of errors. In AIX 5L Version 5.3, the cfgmgr command reports the cause.
• Administrative control of the user trace buffers
  In previous versions of AIX, the trace buffer size for a regular user is restricted to a maximum of 1 MB. Version 5.3 allows the system group users to set the trace buffer size either through a new command, trcctl, or using a new SMIT menu called Manage Trace.
• Core file creation and compression
  AIX 5L Version 5.3 allows the users to compress the core file and specify its name and destination directory. Two new commands, lscore and chcore, have been introduced to check the settings for the corefile creation and change them, respectively.
• snap command enhancements
  AIX 5L Version 5.3 provides an interface to the snap command, which can be used by third parties to provide snap routines (scripts) in support of collection of data for their own applications in the snap dump. The third-party scripts enable owners of individual snap components to specify and maintain their own snap code.
• Splitting the snap file from the snap command
  The functionality of the snap command has been enhanced so that it can now split the snap output file into user-specified sizes (smaller). To do this, the snap command invokes a newly introduced command called snapsplit.
• Several new core RAS functions in the area of Trace and Dump have been introduced. The new Lightweight Memory Trace (LMT) is a highly efficient, always-on trace aimed at First Failure Data Capture. The Minidump stores level 0 crash information into NVRAM, and places it in the error log on reboot. Error Detection facilities have been improved to detect when code runs disabled for interrupts too long. There are new Debug Aids, such as KDB Consistency Checkers and enhanced socket debugging capabilities.
• New RAS capabilities have been implemented for selected AIX Subsystems - Virtual Memory Manager (VMM), NFS, LFS and J2 Filesystems, Asynchronous I/O, Storage Device Drivers, Networking/TCP, Sockets, Streams. (5300-05)
• Core RAS functionality has been expanded for Dump, Trace, Error Detection. (5300-05)
• The "dump" command can now take a wildcard. (5300-05)

System management

• Service Update Management Assistant
  AIX 5L Version 5.3 features an impressive new tool for systems management called SUMA (Service Update Management Assistant). Using SUMA, administrators can define policies to automate unattended downloads of a specific APAR, the latest security updates, or an entire maintenance level directly from the Quick links for AIX fixes Web site. A scheduling module is utilized to allow policies to be run at various intervals in order to conform to a client's maintenance window. SUMA frees administrators from the task of manually retrieving maintenance updates from the Web. Filtering options allow comparisons against an installed software inventory, a fix repository, or a maintenance level to ensure only desired fixes will be downloaded. SUMA provides the option to send an e-mail notification containing a list of what is available for download, as well as detailed summary statistics of a download.
• Security scrubbing feature
  The new security scrubbing feature in AIX 5L Version 5.3 allows an entire disk drive to be overwritten with user-specified patterns and wipes out a drive prior to BOS installation.
• Date APIs past 2038
  The time_t type, which is used to represent time on UNIX® systems, is a 32-bit signed integer on both 32-bit and 64-bit machines. UNIX systems represent time as the number of seconds from January 1, 1970 at 00:00:00 UTC. On January 19, 2038 at 03:14:08 UTC, it will be more than 2³¹ seconds, making it impossible for the date to be represented by a time_t type. Version 5.3 has introduced time64_t type, a 64-bit time API, that allows user programs to call the new time functions to manipulate times up till December 31, 9999.
• Mozilla default browser for AIX
  AIX 5L Version 5.3 introduces support for the Mozilla 1.4.2 Web browser (default browser for AIX). Netscape Communicator Version 4 is not supported on AIX 5L Version 5.3.
• Long user and group name support
  Prior to AIX 5L Version 5.3, there was a limit of eight characters for user and group names. In Version 5.3, the limit has been increased to 255 characters.
• Enhancements to alternate disk installation
  The AIX 5L Version 5.3 has implemented a number of changes to make the alt_disk_install operations easier to use, document, and maintain. Moreover, the alt_disk_install command has been replaced by the following commands:
  • alt_disk_copy
    This command creates copies of rootvg on an alternate set of disks.
  • alt_disk_mksysb
    This command installs an existing mksysb on an alternate set of disks.
  • alt_rootvg_op
    This command performs wake, sleep, and customize operations.
• Network Install Manager (NIM) enhancements
  The following are some of the enhancements that AIX 5L Version 5.3 has made to the NIM environment:
  • Detailed output when creating a NIM lpp_source resource
  • Creating Shared Product Object Tree (SPOT) resource from a mksysb
  • Restoring SPOT copy function
  • Adjustments in NIM to process multiple CD media
  • NIM interface to change network attributes

  In previous versions of AIX, NIM used rsh and rcmd commands to perform remote execution of commands on clients. These r-commands were a potential security exposure. AIX 5L Version 5.3 is enhanced by the nimsh environment that is part of the bos.sysmgt.nim.client fileset. It allows the following two remote execution environments:

  • NIM service handler for client communication -- basic nimsh
  • NIM cryptographic authentication -- OpenSSL

  While the basic nimsh is an easy to use solution with sufficient security, OpenSSL provides additional up-to-date cryptographic security.

  The original rsh or rcmd command environments are still supported in Version 5.3 because of compatibility and ease-of-use reasons.

• 5300-05 introduces Thin Server (NIM diskless/dataless client renamed) and Common OS Image (NIM SPOT resource renamed) Management. This facilitates cloning a common image and performing operations on the clone image thus preventing operation from interfering with running thin servers. This also allows a thin server to switch to a different common image as at a specified time as dictated by the NIM Administrator.
• NIM and SUMA integration (5300-05)
  SUMA and NIM have undergone the following usability enhancements:
  • SUMA can filter against an lpp_source
  • /usr/sbin/compare_report can accept an lpp_source
  • /usr/sbin/geninv: new command to gather inventory
  • /usr/sbin/niminv: new command to gather, compare and conglomerate inventory and download fixes based on NIM objects
• Dynamic support for large page pools
  AIX 5L Version 5.3 allows dynamic runtime resizing of the large page pools without the need of a system reboot. The large pages are changed by the vmo command by changing the lgpg_size and the lgpg_regions attribute.
• System V printer enhancements
  The AIX 5L Version 5.3 includes the following new functionalities or enhancements for System V Printing:
  • The remote lpd printing daemon, lpNet, now provides improved speed and performance.
  • The same JetDirect software now services both AIX printing and System V printing.
  • The lpsched and lpNet programs have been made more secure.
  • Performance of lpsched has been enhanced by improving the filtering process.
  • Error reporting from lpsched and lpNet has been improved.
• Multilanguage Software Bundles "%L in Bundles"
  An AIX product owner might want to create install bundles that contain language-specific filesets. You used to have to make a separate bundle file for each different locale and have the user choose between the multiple bundles. Now you can create a bundle with fileset entries that contain "%L", which will resolve at runtime to the applicable locale.
• mksysb and migrate
  
  The new p5 systems support only AIX 5L Version 5.2 and 5.3 leaving out versions 4.3 and 5.1. A customer who runs a system in either AIX 4.3 or AIX 5L Version 5.1 has no simple migration path to move to the new hardware and the new release of the Operating System. This feature deals with the creation of a method to restore a mksysb and then migrate it to a higher version of the Operating System with a single operation using the available Base Operating System installation mechanisms (for example, TAPE, CD/DVD, Network.)
• Many improvements have been made in each of the following areas for the Virtual I/O Server Command Line Interface:
  • Enhancements to RAS and Usability (Tracing, Error Messages, Man pages, Login Prompt, Additional Unix Utilities)
  • Formatted output (lsdev, lspv, lslv, lsvg, lspath, lssp, lsmap)
  • Storage Pools (new storage concept)
  • New and enhanced commands
• Virtual SCSI Client Heartbeat Failover. Typically, if VIO server hangs, VSCS client hangs as well. If VIO server cannot respond to interrupts, it now acts as if it has crashed. (5300-05)
• Virtual I/O Error Logging has been enhanced. (5300-05)
• Command to show locked users
  
  Provide a command that will show all locked users, including system users with a - in the /etc/security/passwd file. Implemented as 'usrck -l' (lowercase L).
• Add option to ID to show login ID
  
  Add a '-l' (lowercase L) option to the "id" command. This option specifies that the id command write the login ID instead of the real or effective ID. This flag can be invoked with either the -u flag to write the login UID, or the -g flag to write the primary group ID for the login user.
• XNTPD Enhancements
  
  
  • Four new options in /etc/ntp.conf
  • Slewalways option
  • Ignore_bigtimestep option
  • Slewthreshold option
  • Iburst server command option
  • New option to ntpdate command
  • 'c' option
• Installation support is provided for > 1TB disks or logical units. (5300-05)
• RAID capacity limitation now 2TB per array. (5300-05)
• Changes/Enhancements to Web-based System Manager. If PAM (Pluggable Authentication Module) is configured on the system then WebSM will use the PAM services for authentication, otherwise traditional authentication mechanism will be used. (5300-05)

Performance management

• AIX 5L Version 5.3 has introduced a new command called lparstat. It provides a report of partition-related information and utilization statistics. If run in a micro-partition, information like: number of physical processors consumed, percentage of the entitled capacity consumed, percentage of logical processor(s) utilization that occurred while executing at the user and system level, and available physical processors in the shared pool are shown.
• AIX 5L Version 5.3 has introduced a new command called mpstat. It collects and displays performance statistics for all logical CPUs in the system. When the mpstat command is invoked, it displays two sections of statistics. The first section displays the system configuration, which is displayed when the command starts and whenever there is a change in the system configuration. The second section displays the utilization statistics, which will be displayed at user-specified intervals and at any time the values of these metrics are deltas from the previous interval.
• The topas tool has been enhanced to work for micro-partitions. For such partitions, topas report on the number of physical processors and percentage of entitled capacity granted to the partitions. The tool has also been enhanced to display CEC monitoring screen.
• The vmstat, iostat, and sar commands have been enhanced to support Micro-Partitioning and SMT environments.
• The performance management APIs have been enhanced to provide (m:n) pthreads support.
• The performance monitoring tool introduced in AIX 5L Version 5.3 called procmon displays a dynamic, sorted list of processes and information about them. It allows execution of basic administration commands such as kill, renice, and svmon on these processes. The procmon tool is an Eclipse plug-in and has been mentioned under Application development section. The command to start the tool is called perfwb (/usr/bin/perfwb). This launches Eclipse with the procmon plug-in. The perfwb command is contained in the fileset bos.perf.gtools.perfwb.
• In the previous versions of AIX, there were no tools available to monitor the AIO (Asynchronous I/O). In Version 5.3, the performance kernel libraries have been modified to obtain AIO statistics. The enhanced iostat command can be used as well to monitor AIO statistics.
• AIO Fast Path for Concurrent IO has been implemented. It is similar to the LVM fast path and meant to be used with JFS2 concurrent I/O. This results in less context switching and immediate start of the I/O leading to performance improvement. (5300-05)
• Modular I/O library has been written to support specific I/O intensive applications. (5300-05)
• Performance monitoring tools svmon,vmstat, curt, netpmon, and tprof have been enhanced. Milicode and hypervisor support, automatic performance metric recording and VIOS performance monitoring is provided and/or improved. (5300-05)

Networking

• Prior versions of AIX supported NFS Version 2 and 3. AIX 5L Version 5.3 now supports NFS Version 4, as well as Versions 2 and 3.
• The following enhancements have been made to NFS4:
  Replication Capabilities: On server failures, client switches to an alternate location.
  
  Global Namespace capabilities: Server will redirect client to server where actual data resides. Allows federation of multiple servers into a single NFS namespace.
  
  File Delegation support: When opening a file, the server can grant a delegation to the client, which will guarantee that file data will not be changed by any other client. If another client attempts a conflicting operation on the file, the server will notify the client.
  
  NFS support for existing mount options (previously only used for local filesystems):
  • Direct I/O (DIO) support (mount –o dio)
  • Concurrent I/O (CIO) support (mount –o cio)
  • Release-behind-on-read support (mount –o rbr)
  • I/O pacing support (mount –o minpout=x, maxpout=y)
• NFSv4 Grace Period Support (5300-05)
  When enabled on the server, the server provides a grace period mechanism to aid in quicker and more reliable client recovery of state (open share reservations, locks, etc.) after a server restart. During the grace period, servers only accept reclaim requests from clients attempting to reestablish state.
• Network Data Administration Facility (NDAF) (5300-05)
  This feature reduces the operating cost of NFS by managing data instead of machines (from anywhere). By using a common "global" file namespace, it also provides better file access characteristics for collaboration.
• AIX 5L Version 5.3 supports Stream Control Transmission Protocol (SCTP) and Service Location Protocol Version 2 (SLPv2).
• PMTU discovery in AIX 5L Version 5.3
  The current Path Maximum Transmission Unit (PMTU) discovery implementation uses ICMP Echo Request and ICMP Echo Reply packets to discover PMTU. Some system administrators set up their firewall to drop ICMP Echo packets, resulting in the above method of PMTU discovery to fail. The PMTU discovery mechanism in AIX 5L Version 5.3 is implemented with TCP packets and UDP datagram instead of ICMP Echo packets.
• Command to display PMTU table
  Beginning with AIX 5L Version 5.3, when the PMTU discovery is attempted for a destination, a pmtu entry gets created in a PMTU table. This table can be displayed using the pmtu display command. Accumulation of pmtu entries can be avoided by allowing unused pmtu entries to expire and be deleted.
• Multipath routing
  The Multipath routing feature of AIX 5L formerly supported only round-robin strategy. AIX 5L Version 5.3 enhances multipathing by providing other strategies. Configurable Multipath routing strategies are now included in the SMIT mkroute fastpath.
• IPv6 functional updates
  AIX 5L Version 5.3 is fully compliant with RFC 3542: Advanced sockets API for IPv6. This API supports advanced applications, which typically use raw sockets to access IPv6 or ICMPv6 header fields. Also, a number of new library functions have been implemented that allow applications to easily construct IPv6 extension headers.
• DHCPv6 support
  DHCP implemented in the previous versions of AIX only supports IPv4. AIX 5L Version 5.3 supports DHCPv6, which uses IPv6.
• Interface layer support for hotplug network adapters
  Prior to AIX 5L Version 5.3, the number of network interfaces defaults to 256. It's a configurable network option called ifsize, which determines the maximum number of interface layer structures supportable for that interface type. The current maximum acceptable value for ifsize is 1024. In AIX 5L Version 5.3, any number of interfaces (real or virtual) can be supported by implementing if_layer hotplug support. At the time of writing, this support is available only for Ethernet.
• BIND domain search improvement
  In prior releases of AIX, a user can specify up to three nameserver lines and a maximum of six domain names on the search line in /etc/resolv.conf file. The DNS resolver uses either a TCP or UDP socket for the hostname and IP address resolution. Unless user application mandates otherwise, the resolver, by default, uses UDP connection. There are cases when the resolver might send out multiple queries using UDP connection before it can resolve the name. For each query, it will do socket(), sendto(), poll(), recvfrom(), and close() in sequence. For multiple queries, there will be multiple socket() and close() calls. This causes performance degradation.
  
  In AIX 5L Version 5.3, the UDP socket is kept open for multiple queries against the same nameserver until it finishes the name resolution and then calls close() once to close the UDP socket. In general, this results in performance improvement. Also, the limit of six domain names on the search line has been replaced by the number of characters in the search string with a maximum value of 1024. The search keyword can now support any number of domain names, as long as the number of characters do not exceed 1024.
  
  AIX 5L Version 5.3 has withdrawn support for BIND Version 4.
• A new Fibre Channel RAS command, fcstat, has been introduced. It is similar to entstat, and displays Fibre Channel adapter device driver statistics. (5300-05)
• Open source software IPFilters (version 4.1.13) has been ported. It can be used to provide network address translation (NAT) or firewall services. (5300-05)
• Lower Granularity for TCP's Retransmission Timer. Currently, Retransmission Timer is handled by tcp_slowtimo() function which runs every 500ms. The timer-wheel algorithm is now used to achieve lower granularity for Retransmission Timer. (5300-05)
• 5300-05 allows non-root users to open Raw Sockets.

Security, authentication, and authorization

• The initial login license limit has been increased from two to 32,767.
• AIX 5L Version 5.3 has made access control more secure by tightening the shadow passwords and authentication maps through use of the passwd.adjunct map.
• Pluggable Authentication Module (PAM)
  In AIX 5L Version 5.3, the PAM infrastructure has been enhanced to include additional authentication modules. The use of PAM as an authentication mechanism is now a system-wide decision rather than per user.
• LDAP enhancements
  The AIX 5L Version 5.3 LDAP client supports server-based authentication. This allows the authentication to occur on the server rather than on the client. It can also establish the connection to the LDAP server using kerberos, instead of having to rely on a hard-coded password.
  
  The AIX 5.3 LDAP client allows for the administrator to specify which (of multiple) LDAP servers is to be used, if it's available. Previous LDAP clients did not allow the client to specify a server. This allows system administrators to set up different user communities on specific servers to provide load balancing across the LDAP environment.
  
  AIX 5L Version 5.3 has extended the netgroup support to LDAP.

Enhancement of base commands and libraries

• The find command has been enhanced to provide information on file access and changes in the last N minutes (instead of days).
• The ps command has been enhanced to provide process hierarchy information and a listing of descendant processes for given pid(s).

  This command now supports process lines >2048 characters. Before when directing ps -f output into a file, length was truncated to 2K characters for each line. This limit has been removed. However, on display to tty the lines get truncated to fit width of tty. (5300-05)

• A new flag has been added to the tar command, which would specify the list of files and/or directories to be excluded from the tar file being created, extracted, or listed.
• Flags have been added to the tar command to process a directory of files recursively. An option has also been added to specify an input file for tar extraction much like that can be used for tar creation.
• The fuser command has been enhanced to accept any of the signals displayed by the kill -l command.
• Text processing commands ed/ex/vi support unlimited line lengths.
• Previously, when inserting and deleting text using vi, buffer was not saved if it had over 1024 (1K) characters. Now, buffer is unlimited. (5300-05)
• vi and ex can handle files up to 2GB.
• Support for unlimited number of fields and size of a line for awk.
• Command buffer sizes are now unlimited. This allows increased number of arguments on command line.
• An option has been added to the restore command to exit on error, rather than recover and continue. The command also has a new option to provide a long style listing of backup files as in ls -l.
• Options have been added to the grep command to do recursive search.
• The snap command now includes installed package information from System V and rpm.
• A restricted version of ksh and ksh93 is now available.
• The cron function now accepts user-specified location, type, and size for the cron log file when specified in the /etc/cronlog.conf configuration file.
• Formerly, cron and at mailed output only; mail had no subject. Mail subject now provides command name, user name, and exit status.
• Queues g-z are now available for user-defined queues at jobs.
• A flag has been added to the at command so that you can see both the time of the job and the actual command that is scheduled to run.
• An option has been added to nohup command to nohup an existing process.
• "+=" operator has been added to the make command.
• With a new environment variable EXTENDED_HISTORY, the shell histories in ksh and ksh93 will have a time stamp.
• Search highlighting has been added for the more command. When matching a search pattern, all matches of the search pattern are now highlighted. Highlighting is the default; new '-H' option disables highlighting. 'H' can also be used as a subcommand in an active 'more' session to toggle highlighting on or off.

Conclusion

AIX 5L Version 5.3 has many more features than have been discussed here. As was mentioned at the outset, I wanted to focus only on a subset of these enhancements for the sake of brevity. I hope that the article has given you a flavor of the sort of things you can expect in Version 5.3. The publications listed in the Resources section provide further details on the subject.

Resources

Learn

• The AIX 5L Differences Guide Version 5.3 Edition (developerWorks, December 2004) redbook focuses on the differences introduced in AIX 5L Version 5.3 when compared to AIX 5L Version 5.2.
  
  
• Advanced POWER Virtualization on IBM System p5 redbook provides an introduction to Advanced POWER Virtualization on IBM eServer™ p5 servers.
  
  
• Read "AIX updates Version 3: How to work the puzzle" (developerWorks, April 2006), to find answers to your questions regarding AIX updates.
  
  
• Read "Update your AIX system with SUMA" (developerWorks, April 2006), to examine issues surrounding AIX updates and how to implement specific steps to overcome them.
  
  
• Read the AIX 5L Service Strategy and Best Practices document.
  
  
• The IBM eServer pSeries® and AIX Information Center provides the latest documentation on the AIX.
  
  
• The suma Command main page provides information on the various options on SUMA and usage examples.
  
  
• Check out other articles and tutorials written by Shiv Dutta:
  • AIX and UNIX zone
  • Across IBM and developerWorks
  
  
• AIX and UNIX: The AIX and UNIX developerWorks zone provides a wealth of information relating to all aspects of AIX systems administration and expanding your UNIX skills.
  
  
• New to AIX and UNIX: Visit the New to AIX and UNIX page to learn more about AIX and UNIX.
  
  
• AIX 5L Wiki: A collaborative environment for technical information related to AIX.
  
  
• IBM Virtual Innovation Center for Hardware: This site is the primary source for all System p AIX development.
  
  
• developerWorks technical events and webcasts: Stay current with developerWorks technical events and webcasts.
  
  
• Technology bookstore: Browse this site for books and other technical topics.
  
  
• Podcasts: Tune in and catch up with IBM technical experts.
  
  

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Table of contents

• Introduction
• General observations
• AIX 5L Version 5.3 features and functionality
• Conclusion
• Resources
• About the author
• Comments

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