AIX 7.3.4 Release Notes

The installation hints and tips are available at the AIX Installation tips article.

In some instances, the software license agreements (SLA) might not be displayed correctly. In this event, the license agreements can be viewed for all languages at the Software license agreements website.

Starting with AIX® 7.3 Technology Level (TL) 3 Service Pack (SP) 1, a new fileset bos.licenses, is included as part of the operating system installation. In addition to the license agreement accepted during the installation, a copy of the license is stored in /usr/swlag/<locale> file, with a suffix that indicates the corresponding release, TL, and SP. Subsequent updates applied after you install AIX 7.3 TL3 SP1 include extra licenses or notice files that are delivered through the bos.licenses fileset.

In AIX 7.3, a separate software maintenance agreement (SWMA) acceptance window displays during installation immediately after the license acceptance window. The response to the SWMA acceptance (accept or decline) is stored on the system. Either response allows the installation to proceed, unlike license acceptance, which requires you to accept to proceed.

The SWMA acceptance window is displayed during a new overwrite or preservation installation from base DVD media.

For NIM installations, if licenses are accepted either from the choices that are made when you initialize the installation, or by using the ACCEPT_LICENSES field in a customized bosinst.data file, SWMA acceptance is constituted.

IBM Power10 processor-based servers, or later, include technology that helps you keep your SWMA current. You can apply for AIX updates and receive support from IBM. The server uses an AIX update access key (UAK) that indicates the expiration date of the associated AIX SWMA agreement for the server. Provides notification of SWMA expiration to ensure continued and uninterrupted software support. For more information about AIX UAKs, see the AIX update access key topic. You can find additional information in the Management of AIX Update Access Keys support article.

Note: Starting from AIX 7.3 Technology Level 4 (TL4), along with the informational messages, AIX updates and the migrations are blocked if the operating system level of the AIX passed the expiration date of the AIX UAK.

You can download AIX fixes and search technical databases (including authorized program analysis report (APAR) and tips for AIX administrators) at the Fix Central website.

Security subscription services are available at the My notifications website.

After you subscribe to the AIX security advisories, you will receive the advisories by email when they are published.

Only 64-bit Common Hardware Reference Platform (CHRP) systems that runs selected POWER8, POWER9, Power10 processors in POWER8, or later, and Power11 processors in POWER9, or later. Processor compatibility mode that implements the Power Architecture Platform Requirements (PAPR) is supported.

prtconf | grep 'Processor Type'

AIX 7.3.4 minimum current memory requirements vary, based on the configuration.

A minimum current memory requirement for AIX 7.3.4 is 2 GB.

AIX 7.3.4 requires the minimum current memory requirement to increase as the maximum memory configuration or the number of devices scales upward, or both. High maximum memory configurations, LMB capacities, or extra devices scale up the minimum current memory requirement. If the minimum memory requirement is not increased along with the maximum memory configuration, the partition hangs during the initial program load (IPL).

AIX 7.3, and later creates a 512 MB paging space (in the /dev/hd6 directory) for all new and complete overwritten installations.

Starting with AIX 7.3, the minimum capacity of the boot logical volume (hd5) is 40 MB.

The installation operation, which includes the operating system overwrite installation, operating system preservation installation, and operating system migration installation, create or increase the capacity of the hd5 logical volume to a minimum of 40 MB.

Before you migrate an operating system, run the premigration script that is available in the usr/lpp/bos directory, in your media, or in your NIM Shared Product Object Tree (SPOT). The premigration script checks whether the capacity of the hd5 boot logical volume is at least 40 MB. If the capacity of the hd5 logical volume does not meet the requirements, the premigration script checks whether the required free partitions are available. The partitions that are allocated for the hd5 boot logical volume must be contiguous and must be located within the first 4 GB space of the disk.

AIX 7.3, and later, requires a minimum of 20 GB of physical disk space for a default installation that includes all devices, the Graphics bundle, and the System Management Client bundle.

Serial Attached SCSI (SAS) RAID controllers and Fibre Channel controllers support attached arrays and disks with capacities, which exceed 2 TB. The maximum supported capacity (beyond 2 TB) is limited by either the attached storage subsystem or the higher-level logical storage management.

For more information about SAS RAID controllers, see the SAS RAID controller for AIX topic.

For more information about AIX capacity limitations for logical storage, see the Limitations for logical storage management topic.

For AIX 7.3, and later, the qualified and supported maximum capacity of the Enhanced Journaled File System (JFS2) file and file system is 128 TB.

For AIX 7.3.1, and later, the Network File System (NFS) client supports file capacities that are greater than 16 TB. The current tested and supported maximum file capacity is 256 TB. For improved performance, use the NFS direct I/O (DIO) option with high capacity files.

Starting with AIX 7.3, the default file name extension is changed from .Z to .gz for the pax file that is compressed by using the snap command. The snap.pax.gz file is the default pax file that is compressed by using the snap command.

AME on AIX now has a default page capacity of 64 KB on Power10 processor-based systems.

Starting with AIX 7.3, TL3, AIX has a virtual ethernet multi-queue feature. This feature helps to drive more network traffic through virtual ethernet adapter. By default, there are 12 transmit queues and zero receive queues (legacy receive mode). To increase the bandwidth, you can increase the number of receive queues on a virtual Ethernet adapter by using the queues_rx tunable attribute. However, using multiple receive queues to drive more traffic requires more CPU resources.

Starting with AIX 7.3 TL3, AIX introduced a dynamic optimization that promotes 64 KB application text pages to 16 MB pages. This feature applies exclusively to applications that are reasonably busy and have a binary capacity of at least 16 MB. This feature is enabled by default.

For more information about the optimization, see the Large page optimization topic.

Starting with AIX 7.3 TL3, AIX supports the dynamic socket buffer sizing feature for TCP connections. A new network option tcp_dss tunable parameter is introduced, which enables or disables this feature and can be modified by using the no command. If this feature is enabled, TCP attempts to automatically update the socket send buffer and receive buffers to achieve better bandwidth, especially in long distance and high latency network communication. If the application sets TCP send or receive buffer by using the setsockopt system call, dynamic socket buffer sizing is not performed for that particular connection. This option is enabled by default.

When Power10 systems run in shared processor mode, the default value of the throughput mode for the virtual processor management (VPM) is 2. When you migrate the system to or from a Power10 system, and later, the AIX operating system automatically changes the default value of the throughput mode for the VPM. During boot operation, the AIX operating system selects the default value of the vpm_throughput_mode tunable parameter of the schedo command based on the type of server on which the LPAR is running. The value of the vpm_throughput_mode tunable parameter that the AIX operating system selects is preserved and used on the destination server.

Starting with AIX 7.3 TL2, the default value of the vpm_throughput_mode tunable parameter of the schedo command is selected based on the destination server. If the value of the vpm_throughput_mode tunable parameter is modified at the source server, the same value is preserved at the destination server.

On Power10 systems, you can switch to the recommended value of 2 for the vpm_throughput_mode tunable parameter by using the following command:

schedo -d vpm_throughput_mode

Starting from IBM® AIX 7.3 Technology level 4 CAA supports NVMe disks as cluster repository disk.

Starting from IBM AIX 7.3 Technology level 4, a new infrastructure that enables live update of AIX libraries such as libc and libpthread are introduced.

A new bundle offering is available to install the following filesets that are not installed by default: bos.net.tcp.ftp, bos.net.tcp.ftpd, bos.net.tcp.telnet, and bos.net.tcp.telnetd.

# installp -e /tmp/install.log -aXd software_source bos.dsc

The minimum capacity of the boot logical volume is 40 MB. If your current boot logical volume is lesser than this value, the installation process tries to increase it. However, partitions in a boot logical volume must be contiguous, and within the first 4 GB on the disk. If your system does not have free space that meets these requirements, a message indicates that the system does not have enough space to expand hd5 (the boot logical volume).

To install AIX 7.3.4, follow the instructions in the Installing the base operating system topic.

Network Installation Management (NIM) includes a readme file that is installed with the NIM Master bos.sysmgt.nim.master fileset. The path name of the file is /usr/lpp/bos.sysmgt/nim/README.

In AIX 7.3, and later, you can continue to use DVD media to write and restore the mksysb image. However, based on the broader industry trends, the AIX operating system has reduced emphasis on DVD as a core technology for the backup and restore operations of the mksysb image. If you rely only on DVD mksysb image, you are encouraged to explore alternative methods of using mksysb image capabilities.

In addition to installation images, cloud-ready images are available in RAW format that can be readily deployed with PowerVC. These images contain a default AIX base media installation configuration that includes the cloud-init software package and its dependencies.

Starting with AIX 7.3, the cloud-ready images in qcow2 format are no longer available.

Starting with AIX 7.3 TL3, a mksysb image that is equivalent to the AIX cloud-ready image is available to be downloaded from IBM Entitled Systems Support (ESS).

IBM software development kit (SDK) and Java™ Runtime Environment (JRE) for AIX, Java Technology Edition is released in JavaV.x filesets, where V represents the version of Java, such as Java 8, and x is the individual fileset, such as Java8_64.sdk.

Only Java Version 8, 64-bit, is installed for new overwrite or preservation operating system installation. For these installations, the PATH variable in the /etc/environment file points to java8_64. If you perform an operating system migration to AIX 7.3, or later, all previous levels of Java remain on the system, and the /etc/environment PATH variable is not changed. Later, if you remove the previous levels of Java (Java Version 6 and Java Version 7), then you must change the /etc/environment PATH variable to point to java8_64.

It is recommended to use java8_64. There is no support for security vulnerabilities in Java Version 6.

To check whether a more recent service refresh is available for a version of Java, see the AIX Download and service information website.

security.pksus

A secure framework for object storage, that uses storage from the hypervisor to store objects securely.

bind.rte

BIND 9.18 Domain Name System support for the AIX operating system.

tmux.rte

A terminal multiplexer.

rsync.rte

A fast, versatile, remote, and local tool to copy files.

opencki.base

OpenCryptoki package which provides the capability to perform cryptographic operation by using hardware or software token is now shipped in default AIX image.

cacerts.base

The Mozilla CA root certificate bundle is now installed by default in AIX image. The fileset name is cacerts.base and the CA certificates will be installed by default at /var/ssl/certs directory

Starting with AIX version 7.3, TL1, the bos.net.tcp.bind and bos.net.tcp.bind_utils filesets are replaced by the bind.rte fileset. The bind.rte fileset is not installed by default.

The bind.rte fileset is built to support the OpenSSL 3.0 and hence openssl.base 3.0.0.0 fileset must be present before bind.rte is installed.

Starting with AIX 7.3, the bos.net.tcp.ntp and bos.net.tcp.ntpd filesets are replaced by the ntp.rte fileset that is installed by default.

Starting with AIX 7.3, the zlibNX accelerated zlib compression library is moved from the expansion pack to the base media and the compression library is installed by default. The bos.perf.pmaix package is no longer part of the AIX operating system.

The core code for each original fileset is in the bos.net.tcp.client_core and bos.net.tcp.server_core filesets. Requisites for software that is shipped with the AIX operating system (the bos.net.tcp.client and bos.net.tcp.server filesets) are changed to the bos.net.tcp.client_core and bos.net.tcp.server_core filesets. Additional requisites are added to the other new fileset as needed.

The original filesets still exist to satisfy any requisites from other software. The original filesets have requisites to all the new filesets to ensure that all the requirements are met.

To remove any of the new filesets, you must first remove either the bos.net.tcp.client fileset or the bos.net.tcp.server fileset. To remove the bos.net.tcp.client fileset, the bos.net.tcp.server fileset, or a new fileset, run the lslpp -d fileset_name command. If no other software has requisites to the fileset that you want to remove, the removal is possible.

During an operating system migration, code changes occur, so that all the system configuration and user configurable files, which were owned by the bos.net.tcp.client and bos.net.tcp.server filesets, are merged by the new filesets that now own the files.

The list of new filesets follows:

• bos.net.tcp.client_core
• bos.net.tcp.server_core
• bind.rte
• bos.net.tcp.bootp
• bos.net.tcp.dfpd
• bos.net.tcp.dhcp
• bos.net.tcp.dhcpd
• bos.net.tcp.ftp
• bos.net.tcp.ftpd
• bos.net.tcp.gated
• bos.net.tcp.imapd
• bos.net.tcp.mail_utils
• bos.net.tcp.pop3d
• bos.net.tcp.pxed
• bos.net.tcp.rcmd
• bos.net.tcp.rcmd_server
• bos.net.tcp.sendmail
• bos.net.tcp.slip
• bos.net.tcp.slp
• bos.net.tcp.snmp
• bos.net.tcp.snmpd
• bos.net.tcp.syslogd
• bos.net.tcp.tcpdump
• bos.net.tcp.telnet
• bos.net.tcp.telnetd
• bos.net.tcp.tftp
• bos.net.tcp.tftpd
• bos.net.tcp.timed
• bos.net.tcp.traceroute
• bos.net.tcp.x500
• bos.net.tcp.cpd

The encoded software in the bos.net.uucp fileset moved to the bos.net.uucode fileset.

The IBM License Metric Tool version 7.3 is no longer supported. To learn more about the replacement version of IBM License Metric Tool Version 9.x, go to IBM License Metric Tool 9.2.

IBM PowerSC Trusted Surveyor is not supported in AIX 7.3, and later. If you are migrating to AIX 7.3, or later, you must remove the powersc.ts fileset before you start the migration process. If you have WPARs that you are migrating, you must verify that the powersc.ts fileset is not installed on the WPARs.

When you upgrade to AIX 7.3, or later, RSCT Version 3.3.0.0 is installed and replaces the previous version of RSCT. For more information about RSCT, see the IBM Docs for RSCT 3.3.

AIX 7.3 (and later) and RSCT Version 3.3.0.0 no longer support the Virtual Shared Disk (VSD) and low-level application programming interface (LAPI) products. If these products are already installed from an older code level, both the rsct.vsd and rsct.lapi.rte filesets must be removed before migrating to AIX 7.3, or later. If you have third-party products that use VSD, you must review the current Spectrum Scale product offerings for a replacement.

The filesets that end with .sp are no longer used by any products currently. If you still have these filesets that are installed at any supported AIX version, you can uninstall them whenever convenient. The filesets that end with .hacmp are still needed by some products at older AIX versions, but no longer required in AIX 7.3, and later. If you still have these filesets that are installed after you migrate to AIX 7.3, or later, you can then remove them whenever convenient.

The dsm.core fileset ships a /etc/ibm/sysmgt/dsm/overrides/dsm.properties file that allows you to override SSH configuration. If this file was modified, the file needs to be backed up manually before an update or a migration, as it is overwritten.

If you migrate any previous version of the AIX Common Operating System Image (COSI) and associated AIX Thin Servers to the AIX 7.3 (or later), it is recommended that you delete any dump device that is associated with the migrated Thin Servers and re-create the Thin Servers.

Also, you must install the devices.tmiscsw.rte fileset on the NIM master for the AIX 7.3 Thin Server to create a dump device. The devices.tmiscsw.rte fileset is available in the AIX Expansion Pack.

AIX Version 7.3, and later, does not support the IBM Subsystem Device Driver (SDD) for IBM TotalStorage Enterprise Storage Server, the IBM TotalStorage DS family, and the IBM System Storage SAN Volume Controller. If you are using SDD, you must move to Subsystem Device Driver Path Control Module (SDDPCM) or AIX Path Control Module (PCM) for the multipath support on AIX for IBM SAN storage. SDD to SDDPCM migration scripts are available to help you with the transition.

Contact IBM storage technical support to request access to the migration scripts.

For more information about the available Multipath I/O solutions and supported AIX versions for IBM SAN storage products, see the IBM System Storage Interoperation Center (SSIC) website.

IBM Db2 Version 11.1 with FP5 is available on the AIX base media. You can upgrade your Db2 environment from Db2 Version 10.5, 10.1, or 9.7 to Db2 Version 11.1. For more information about upgrading to Db2 Version 11.1, see the Upgrade to Db2 Version 11.1 topic.

When you change a device attribute while the device is in the open state, the device attribute changes dynamically. In the AIX operating system, you can change specific device attributes while the device is in the open state by running the chdev command with the -U flag. Some of the device attributes in AIX 7.3, and later, that support dynamic change are as follows:

• queue_depth attribute for MPIO disk devices.
• rw_timeout attribute for Serial Attached SCSI (SAS) Fibre Channel and iSCSI disk.
• num_cmd_elems attribute for Fibre Channel adapter protocol devices.
• io_dma attribute for Fibre Channel adapter devices.
• fast_lnk_recov attribute for Fibre Channel adapter protocol devices.
• mt_qk_io_recov attribute for Fibre Channel adapter protocol devices.

You can adjust the protocol stack of your unique networking environment by using the AIX networking options. You can now use the no command to dynamically configure the following TCP retransmission timeout values:

• rto_high
• rto_length
• rto_limit
• rto_low

AIX 7.3, and later, supports scheduling periodic diagnostics multiple times a day instead of only once per day. To schedule periodic diagnostics multiple times a day, run the diag command and select Task Selection > Periodic Diagnostics and specify a time interval between each test.

AIX 7.3, and later, supports formatting and certifying up to 10 disks in parallel instead of a single at a time. To format or certify multiple disks, run the diag command and from the Task Selection menu, select Certify Media in Parallel or Format Media in Parallel. All eligible resources are displayed in a list. You can select up to 10 disks from the list. The status of the operation is updated every 5 seconds. The time the operation takes to complete for each disk is based on various factors such as disk type, capacity, and speed.

The usage of the trace facility is now limited to the root user by default.

AIX 7.3, and later, updated the Enhanced Korn shell (ksh93) from the t version to the u+ version. Applications that rely on the specific exit values for the shell (instead of 0 or nonzero) might not be compatible with the u+ version of the ksh93 shell. The exit status of the ksh93 shell is modified to align with the ksh93 community. For compatibility with earlier versions of AIX, the default shell remains ksh (also known as ksh88). The ksh shell is not enhanced for any new functions or performance. However, if feasible, support is provided to address any critical security vulnerabilities. The users of the ksh shell must consider to use the ksh93 shell. In AIX 7.3.4, the bash shell is also available. A future AIX update might replace the default AIX shell with the ksh93 shell.

You can use the lparstat -E 1 command to report the calculated processor frequency per logical partition. You can use the mpstat -E 1 command to report the calculated processor frequency per virtual processor. AIX 7.3, and later, enhances the pmcycles -M command to report the measured processor frequency. AIX 7.3 (and later) also supports collection of EnergyScale power and performance mode and processor frequency information on Power10 processor-based servers, and later, by using the lparstat -N command.

Starting with AIX 7.3, TL2, getcwd and getwd subroutines use a caching algorithm to retrieve the path name of the current working directory. To disable the caching operation, set the environment parameter AIX_CWD_CACHE to OFF.

Starting with AIX 7.3 TL3, it is not required to reduce the number of storage protect keys that are enabled on the system to configure cache capacity exceeding 20 TB.

Starting with AIX 7.3 TL4, a server-side cache of storage data (AIX flash cache) is improved to use less system memory during configuration of cache.

Starting with AIX 7.3 TL2, IBM Security Directory Server (ISDS) is upgraded and is renamed as IBM Security Verify Directory (ISVD). The fileset for ISDS Version 6.4.0.25 is upgraded to ISVD Version 10.0.0.1. The fileset version and the name change for the directory have no impact on how the ISVD functions. The ISVD Version 10.0.0.1 fileset is shipped with AIX 7.3 TL2 and AIX 7.2 TL5 base packs. The AIX 7.3 with TL2 base pack also includes the latest and stable Lightweight Directory Access Protocol (LDAP) filesets that provide fixes for the earlier issues.

The ISVD version 10.0.4.1 might experience issues on the POWER8 servers or when you try to operate the POWER8 compatibility mode on new Power servers. To resolve the issue, see the recommended fix available at Fix Central or contact IBM support for assistance.

When you migrate from AIX 7.2 to AIX 7.3, or later, if the logical partition has Java 8 32-bit SR6FP35 (VRMF 8.0.0.635) installed, you must upgrade the Java version to a later level that can be downloaded from the Java SDK on AIX page. Java 8 32-bit SR6FP35 (VRMF 8.0.0.635) might not load properly on AIX 7.3 (or later).

If a newer version of Java is not available, Java 8 32-bit SR6FP30 (VRMF 8.0.0.630) images are provided on AIX 7.3.4 Expansion pack. You can force-install this Java image to revert to an earlier version that does not have any loading issues.

Starting with AIX 7.3 TL4, Open Source Secure Sockets Layer (OpenSSL) is updated to version 3.0.16.1000 to address some of the vulnerabilities.

Starting with AIX 7.3 TL3 SP1, the OpenSSL version is updated to 3.0.15.1001. This update introduces support for using the in-core capability available on Power11 systems to enable enhanced performance for various cryptographic algorithms.

Starting with AIX 7.3 TL3, the OpenSSL version is updated to 3.0.13.1000. The OpenSSL version 3.0.13.1000 contains performance optimization for Advanced Encryption Standard (AES) with -GCM and -XTS modes and ChaCha20 stream cipher on Power10 systems

Starting with AIX 7.3 TL1, OpenSSL is updated from version 1.0.2 to 3.0.7. As a result of new updates in AIX 7.3 TL1, a few APIs are deprecated, weak ciphers are removed, support for Transport Layer Security (TLS) version 1.3 is introduced, and provider concepts are introduced.

The AIX operating system ensures that the existing applications do not get impacted by the version update. Hence, the shared objects of OpenSSL 1.0.2 and OpenSSL 1.1 are retained in the OpenSSL library. The applications that depend on OpenSSL libraries must migrate to OpenSSL 3.0 before the end of support for the previous versions.

Notes:

• OpenSSL version 1.0.2 is no longer supported since the beginning of January 2024. OpenSSL version 1.1 will no longer be supported after December 2025.
• Shared objects of OpenSSL version 1.0.2 and 1.1.1 will be removed from the archive during AIX 2025 Fall release and hence clients are encouraged to move their workload environments to use 3.0 shared object.
• The shared objects of OpenSSL version 0.9.8 are no longer supported and libcrypto_compat.a and libssl_compat.a libraries are removed since they contain only 0.9.8 shared object. Also the libraries libcrypto.a and libssl.a does not have 0.9.8 shared objects in them. As a mitigation, customers who depend on these shared objects are now recommended to compile their applications against the latest supported shared objects.

The new symbols that are introduced in the OpenSSL 3.0 configuration file are stored in the /var/ssl/openssl.cnf file. It is recommended to backup and save the changes in the old configuration file because the old OpenSSL configuration file is not retained for the use.

openssl_conf = openssl_init

 [openssl_init]
 providers = provider_sect

 [provider_sect]
 default = default_sect
 legacy = legacy_sect

 [default_sect]
 activate = 1

 [legacy_sect]
 activate = 1

For more information about updates between OpenSSL 1.0.2 and OpenSSL 3.0, see the community migration guide (https://www.openssl.org/docs/man3.0/man7/migration_guide.html).

To raise any queries, see IBM AIX support website.

You can download the latest version of the OpenSSH fileset from the AIX Web Download Pack Programs website.

AIX 7.3, and later, includes OpenSSH as part of the minimal AIX installation.

GSKit version 8.0.55.19 is provided on the AIX 7.3 Expansion Pack media.

Use GSKit version 8.0.50.10, or later, when you use IP Security with Rivest-Shamir-Adleman (RSA) key lengths that are greater than 2048 bits. The minimum RSA key length of 2048 bits is a requirement for complying with the National Institute of Standards and Technology (NIST) standard as defined in Special Publication 800-131A. When you generate certificates for IP security (IPsec), consider the requirements that are listed in Installing the IP security feature.

The previous version of Perl was upgraded to Perl Version 5.38.2.0. Perl is a separate 3rd-party open source package that is not owned by IBM. The Perl package might not preserve full compatibility across all versions. If you are moving Perl scripts to version 5.38.2.0, you must complete an evaluation of the scripts to verify that they continue to work as expected. For more information about Perl, see the Perl Programming Documentation website.

Starting with AIX 7.3 TL4, Python 3.11 is the default Python 3. Python 3.9 from fileset python3.9.base is out of support from Python community, and it is not installed by default now. Python 3.9 remains in the media only for binary compatibility purposes. Python 3.9 will be removed in the future releases. Python 3.11 is updated to version 3.11.13 and Python 3.9 is updated to version 3.9.23.

Python 3.11 is built by using the OpenXL compiler 17.1.2 with Link-Time Optimization (LTO) and Profile Guided Optimization (PGO) enabled. To build Python C or C++ extension modules, OpenXL compiler 17.1.2 is required.

Starting with AIX 7.3 TL4, the Tool Command Language (Tcl) and Tool Kit (Tk) is updated to version 8.6.16. It is available through tcl.base and tk.base filesets. The Tcl and Tk is a third-party open-source package and is not owned by IBM. For more information, refer https://www.tcl-lang.org/ page.

Starting with AIX 7.3 TL4, the RPM version is upgraded to 4.20.1. The cacerts.base fileset that is related to SSL certificates similar to the AIX Toolbox CA certificates RPM package is shipped. If the cacerts.base fileset is installed, you must not install the CA certificates RPM package from AIX Toolbox.

Starting with AIX 7.3 TL2, the RPM version is upgraded to 4.18.1. The RPM version 4.18.1 uses sqlite3 library package as a database backend instead of the db library package and is built with OpenSSL instead of nss and nspr library packages. The nss, nspr, and db library packages are removed from the AIX base image as these library packages were used internally and are no longer needed. You can get the nss, nspr, and db library packages from the AIX toolbox if required.

Starting with AIX 7.3 TL4, Bourne Again Shell (Bash) version is updated to 5.2.37 from 5.2.15 and is installed by default. For more information about locale support, refer Bash Locale Support technote.

Starting with AIX 7.3 TL4, the Terminal multiplexer (Tmux) v3.5a is available through tmux.rte fileset. Tmux is not owned by IBM. It is a third-party open source package. Tmux allows you to easily switch between several programs in one terminal, detach them, while they run in the background, and reattach them to a different terminal. For more information, refer tmux page.

The DBX debugger utility is not compatible with IBM OpenXL C/C++ compiled binary files because of the missing features in DBX DWARF support. Full DWARF support is available in a subsequent release of DBX.

AIX 7.3, and later, does not support YUM as RPM package manager from the AIX toolbox. DNF (dandified yum, the next-generation of the Yellowdog Updater) can be installed from AIX toolbox and must be used to manage RPM packages.

The bos.cifs_fs software package is moved to the AIX 7.3 Expansion Pack media. The Common Internet File System (CIFS) client is provided as-is without support.

The AIX operating system supports up to 256 dedicated or virtual processors. AIX 7.3 supports Simultaneous Multi-threading (SMT-8, SMT-4, SMT-2), and single-threaded (SMT-1) configuration. Each processor contains up to eight hardware threads that allows up to 2048 logical processors to be assigned to a single LPAR when the AIX operating system is configured in SMT-8 mode. You can use the smtctl command to switch the SMT mode that is used by the AIX operating system.

AIX 7.2, and earlier, supports both NTP version 3 and NTP version 4. Both NTP versions are supported by using symbolic links from the /usr/sbin directory to the NTP binary files of one of the NTP versions. Starting with AIX Version 7.3, support for NTP version 3 is removed. For compatibility with earlier versions of NTP, the symbolic links point to NTP version 4 binary files by default so that the same commands continue to work.

AIX version 7.3, and earlier, supports BIND version 9.4.1. Starting with AIX 7.3, TL1, support for BIND version 9.4.1 is removed and support for BIND version 9.16 is added. For compatibility with earlier versions of BIND, the symbolic links point to BIND version 9.16 binary files to ensure that the same commands continue to work.

BIND version 9.16 is included in the bind.rte fileset in AIX 7.3, TL1, base media package. The bind.rte fileset is not installed by default. During migration from the previous AIX version to AIX 7.3, TL1, the bos.net.tcp.bind, and bos.net.tcp.bind_utils filesets that are installed on the previous AIX versions are removed, and the bind.rte BIND fileset is installed. During the update operation, the bind.rte fileset must be explicitly selected for installation. Otherwise, the bos.net.tcp.bind and bos.net.tcp.bind_utils BIND filesets remain in the updated system.

BIND version 9.18 is included in the bind.rte fileset in AIX 7.3, the TL2 base media package.

To view the most current version of the AIX 7.3 information, see the AIX Documentation website.

The IBM AIX Dynamic System Optimizer (DSO) extends the features that are provided by the Active System Optimizer (ASO) to automatically adjust some system settings to maximize the efficiency of the AIX operating system. The DSO automates the difficult job of manually tuning the specific system settings to optimize eligible workloads. The additional features that are provided by DSO are large page optimization and data stream prefetch optimization.

DSO is no longer a stand-alone feature and is included in AIX 7.3, TL1, or later, as a part of ASO. For more information about DSO and ASO, see AIX Dynamic System Optimizer.

For more information about server-side support for new Unicode locales, see the Supported languages and locales topic.

Starting with AIX 7.3 TL4, Low Level Debugger (LLDB), which is part of the Low Level Virtual Machine (LLVM) open source project is available for AIX. You can use LLDB for source level debugging of OpenXL compiled binaries. You can download this from IBM web download page. In the IBM web download page, search LLDB to download the package.

Starting with AIX 7.3 TL4, a technology preview for NVMe over TCP storage connectivity with physical network that is assigned to the LPAR is introduced. The support does not include boot from NVMe over TCP/IP devices. Clients and storage vendors can perform the testing activities.

A new version of OpenSSL 3.5 with quantum safe encryption is available at IBM web download as a tech preview.

Starting with AIX 7.3 TL3, reporting of LVM mirror write consistency check (MWCC) statistics is supported. You can use the lvmstat command to generate the statistics report for an active MWCC. For more information about the MWCC statistics report, see the lvmstat command page.

Starting with AIX 7.3 Technology Level 3, when AIX runs with Power Firmware 1060.10 or later, the Fibre Channel and PCI NVMe direct attach I/O performance is improved. The improvement is with lower I/O capacities such as 4 KB, 8 KB, and 16 KB.

Starting with AIX 7.3 TL4, a new option that is known as authmod is introduced. The authmod option modifies the password of the passphrase key-protection method for LV and PV encryption and allows you to modify the password of the existing passphrase method.