sysdumpdev Command

Purpose

Displays and modifies the information and settings that are related to traditional system dump and firmware-assisted system dump.

Syntax

sysdumpdev -P { -p device | -s device } [ -q ] [ -i ]

sysdumpdev [ -p device | -s device ] [ -q ]

sysdumpdev [ -d directory | -D directory | -e | -I | [ -k | -K ] | -l | [ -n | -N ] | -p device | -q | -s device | -z ]

sysdumpdev [ -i ]

sysdumpdev -L { -v | -S device }

sysdumpdev [ -t { traditional | fw-assisted } ] [ -f {disallow, allow, require }]

Description

The sysdumpdev command changes the primary or secondary dump device designation in a system that is running. The primary and secondary dump devices are designated in a system configuration object. The new device designations are in effect until you run the sysdumpdev command again, or you restart the system.

If you run the sysdumpdev command with the no flag, the sysdumpdev command identifies the current attributes of the primary and secondary dump devices and writes the attribute values to the ODM object class and NVRAM. The default primary dump device is /dev/hd6. The default secondary dump device is /dev/sysdumpnull. If the system has 4 GB or more of memory, then the default dump device is /dev/lg_dumplv, and /dev/lg_dumplv is a dedicated dump device. AIX® Version 7.1, and later, extends firmware assisted dump capabilities to make it as the default system dump method if it is supported by the platform.

Note:
  • A mirrored paging space might be used as a dump device.
  • Do not use a diskette drive as your dump device.
  • If you use a paging device, only use hd6, the primary paging device. The AIX operating system supports using any paging device in the root volume group (rootvg) as the secondary dump device.
  • If you use a removable device such as a tape or DVD, be aware that the dump does not span volumes. Thus, the dump must fit on a single volume.
  • You can configure an iSCSI software initiator device in the root volume group (rootvg) as the dump device for a firmware-assisted system dump, for AIX Version 6.1 with the 6100-01 Technology Level.
  • Remote dumps for thin servers are supported for AIX 6.1. You must define the relative dump resource on the NIM master to see the dump resource on the NIM client as an iSCSI disk that can only be used to configure the primary dump device. Only firmware-assisted system dump can be configured on an iSCSI disk device.
  • For AIX Version 6.1 with the 6100-06 Technology Level, you can configure a firmware-assisted dump of kernel memory.
  • When you configure a dump device for a logical volume that is encrypted and locked, you might see an error message.
  • You cannot configure a dump device for a logical volume if the encryption or decryption of the logical volume is in progress.

For AIX 6.1 and later versions, all dumps are compressed. You should use the savecore command to copy dumps from the dump device to a file.

The sysdumpdev command supports firmware-assisted system dump for the following features:
  • Return of dump size estimation
  • Display of information about most recent dump
  • Detection of a new dump
The sysdumpdev command also provides the dump type including the traditional dump type or the fw-assisted dump type.

The -t flag specifies the type of dump. Its possible values are traditional and fw-assisted.

The -f flag specifies the full memory system dump mode. This mode is relevant only for the firmware-assisted system dump. In this mode, the dump is performed independently of the operating system. All of the partition memory is saved to the dump.

Running sysdumpdev in Non-rootvg Volume Groups

You can use a dump-logical volume outside the root volume group, if it is not a permanent dump device and for a traditional system dump only. For example, if the -P flag is not specified. However, if you choose a paging space, the dump device cannot be copied unless it is in rootvg. If the dump device must be copied, only rootvg is active before paging is started.

The primary dump devices must always be in the root volume group for permanent dump devices. The secondary device might be outside the root volume group unless it is a paging space.

Flags

Item Description
-d directory Specifies the directory the dump is copied to at system boot. If the copy fails at boot time, you can use the -d flag to ignore the system dump.
-D directory Specifies the directory the dump is copied to at system boot. If the copy fails at boot time, you can use the -D flag to copy the dump to an external media.

Note: When using the -d directory or -D directory flags, the following error conditions are detected:

  • directory does not exist.
  • directory is not in the local journaled file system.
  • directory is not in the rootvg volume group.
-e Estimates the size of the dump (in bytes) for the current running system. The size that is shown is the estimated size of the compressed dump.
Item Description
-f{ disallow | allow_kernel | require_kernel | allow_full | require_full } Specifies whether firmware-assisted system dump does allow, require or forbid the dump of either the kernel memory or the full memory. In kernel memory or full memory mode, the dump is performed independently of the operating system. All of the kernel relevant memory is saved to a kernel memory system dump. All of the partition memory is saved to a full memory system dump. The -f flag has the following variables:
  • The disallow variable specifies that neither the full memory system dump mode nor the kernel memory system dump mode is allowed. It is the selective memory mode.
  • The allow_full variable specifies that the full memory system dump mode is allowed but is performed only when operating system cannot properly handle the dump request.
  • The require_full variable specifies that the full memory system dump mode is allowed and is always performed.
When the full memory dump is allowed, the dump size estimation specified with the -e flag corresponds to the memory size with the applied compression factor.
-i Indicates that the sysdumpdev command was called from a system function. This flag is only used by system utilities. The -i flag will not make the requested change if the effected value has already been modified by other than an automatic IBM® function; that is, the -i flag will not override a previous change.
-I Resets the indications of previous changes. After the -I flag is specified, changes are allowed with the -i flag.
-k If your machine has a key mode switch, it is required to be in the service position before a dump can be forced with the dump key sequences.
-K If your machine has a key mode switch, the reset button or the dump key sequences will force a dump with the key in the normal position, or on a machine without a key mode switch.
Note: On a machine without a key mode switch, a dump can not be forced with the key sequence without this value set.
-l Lists the current value of the primary and secondary dump devices, copy directory, and forcecopy attribute. The -l flag also displays the current dump type. The following list indicates the possible values that are displayed:
  • fw-assisted: The preferred dump type is firmware-assisted system dump.
  • fw-assisted (suspend): The preferred dump type is firmware-assisted system dump, but the primary dump device is either not configured or it does not support firmware-assisted system dump. In the latter case, a traditional system dump is triggered.
  • traditional: Only the traditional system dump is available after the sysdumpdev -t traditional command. It might also because the firmware-assisted system dump is not supported on this system. To support firmware-assisted system dump, there must be sufficient memory when the system starts up, and POWER6® or later hardware and the supported firmware must be installed.
start of change-nend of change start of changeDisables the Nest Accelerators (NX) GZIP dump compression. The system dump is compressed without using the NX GZIP.end of change
start of change-Nend of change start of changeEnables the Nest Accelerators (NX) GZIP accelerated dump compression. NX GZIP dump compression is only applicable to firmware-assisted type system dumps.end of change
-L Displays statistical information about the most recent system dump. This includes date and time of last dump, number of bytes written, and completion status. The -L flag shows both the compressed size and the uncompressed size of the dump. The compressed size is the size of what was actually written to the dump device. If no previous dump was recorded in nonvolatile memory, this flag scans the dump devices for the existing dump.
Note:
  1. The dump sizes shown might not reflect the exact size of the dump on the media. There can be a small difference because of disk and copy block sizes.
  2. If the dump has failed due to an I/O error, the major and minor device numbers will be those for the failing device.
-P Makes permanent the dump device specified by -p or -s flags. The -P flag can only be used with the -p or -s flags.
-p device Temporarily changes the primary dump device to the specified device. The device can be a logical volume, writable DVD, or a tape device or an iSCSI disk configured by NIM for remote dump.
-q Suppresses all messages to standard output. If this flag is used with the -l, -z, or -L flag, the -q flag will be ignored.
-s device Device Temporarily changes the secondary dump device to the specified device. The same devices valid for the -p flag are valid here.
-S device Scans a specific dump device for a valid compressed dump. The dump must be from an AIX release with parallel dump support. This flag can be used only with the -L flag.
-t{ traditional | fw-assisted } Specifies the type of dump to perform. The -t flag has the following variables:
  • The traditional variable specifies that the traditional system dump is performed. In this dump type, the dump data is saved before the system reboot.
    Under any of the following circumstances, you can only specify the traditional variable:
    • Firmware-assisted system dump is not supported.
    • Memory is not sufficient when the system starts.
    • POWER6 or later hardware is not installed.

    You cannot use the traditional system dump on an iSCSI software initiator dump device.

  • The fw-assisted variable specifies that the firmware-assisted system dump is performed. In this dump type, the dump data is saved in parallel with the system reboot. If the system starts in a low memory configuration, you must explicitly enable the full memory dump using the -f flag, especially in iSCSI software initiator configuration where firmware-assisted system dump cannot fall back on the traditional system dump if the full memory dump is not allowed.

    If you specify the fw-assisted variable but the primary dump device is either not configured or it does not support firmware-assisted system dump, a traditional system dump is triggered.

When the firmware-assisted system dump type is not allowed at configuration time, or is not enforced at dump request time, a traditional system dump is performed. In addition, because the scratch area is only reserved at initialization, a configuration change from traditional system dump to firmware-assisted system dump is not effective until the system is rebooted.

-v When the dump status is not 0, this option will display available dump debug information. The debug data, when available, is used by service to diagnose dump failures. This flag can only be used with the -L flag.
-z Determines if a new system dump is present. If one is present, a string containing the size of the dump in bytes and the name of the dump device will be written to standard output. If a new system dump does not exist, nothing is returned. After the sysdumpdev -z command is run on an existing system dump, the dump will no longer be considered recent.

If no flags are used with the sysdumpdev command, the default dump devices are used.

Security

Access Control: Only the root user can run this command.

Attention RBAC users: This command can perform privileged operations. Only privileged users can run privileged operations. For more information about authorizations and privileges, see Privileged Command Database in Security. For a list of privileges and the authorizations associated with this command, see the lssecattr command or the getcmdattr subcommand.

Error Codes

Note: A nonzero dump status indicates a failed dump. The following values are the possible dump status values and their corresponding light-emitting diode (LED) values:
Dump status Description LED value
0 Dump completed successfully 0C0
-1 No dump device defined 0C8
-2 Dump device too small 0C4
-3 Dump crashed or did not start 0C5
-4 I/O error 0C1

Examples

  1. To display current dump device settings, enter the following command:
    sysdumpdev -l
    For information about the types of dump that this command shows, see the -l flag description under the Flags section.
  2. To designate logical volume hd7 as the primary dump device, enter the following command:
    sysdumpdev -p /dev/hd7
  3. To designate tape device rmt0 as the secondary dump device, enter the following command:
    sysdumpdev -s /dev/rmt0
  4. To display information from the previous dump invocation, enter the following command:
    sysdumpdev -L
  5. To permanently change the database object for the primary dump device to /dev/newdisk1, enter the following command:
    sysdumpdev -P -p /dev/newdisk1
  6. To determine if a new system dump exists, enter the following command:
    sysdumpdev -z
    If a system dump has occurred recently, an output that is similar to the following is displayed:
    4537344 /dev/hd7
  7. To specify the directory that a dump is copied to after a system crash, if the dump device is /dev/hd6, enter the following command:
    sysdumpdev -d /tmp/dump
    This attempts to copy the dump from /dev/hd6 to /tmp/dump after a system crash. If there is an error during the copy, the system continues to boot and the dump is lost.
  8. To specify the directory that a dump is copied to after a system crash, if the dump device is /dev/hd6, enter the following command:
    sysdumpdev -D /tmp/dump
    This attempts to copy the dump from /dev/hd6 to the /tmp/dump directory after a crash. If the copy fails, you are prompted with a menu. You can copy the dump manually to some external media through this menu.
  9. To scan a dump device for a dump, enter the following command:
    sysdumpdev -L -S /dev/hd6