Saturday, 6 September 2014

Firmware Assisted Dumps

POWER6® processor-based systems enable system dumps to be firmware assisted. When performing a firmware-assisted dump, system memory is frozen and the partition rebooted, which allows a new instance of the operating system to complete the dump.

Firmware-assisted dump is now the default dump type in AIX V7.1, when  the hardware platform supports it. The traditional dump remains the default dump type for AIX V6.1, even when the hardware platform supports firmware-assisted dumps.

To see which kind of dump you are using:

# sysdumpdev -l
primary              /dev/lg_dumplv
secondary            /dev/sysdumpnull
copy directory       /var/adm/ras
forced copy flag     TRUE
always allow dump    FALSE
dump compression     ON

type of dump         traditional

To enable firmware assisted dumps:

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

Full memory dump options available with the sysdumpdev -f command

Option Description

disallow                         Selective memory dump only. A full memory system dump is not allowed. This is the default.
allow | allow_full          The full memory system dump mode is allowed but is performed only when the operating system cannot properly handle the dump request.
require | require_full     The full memory system dump mode is allowed and is always performed

AIX Version 6.1 Technology Level 1 introduced support for an iSCSI device to be configured as a dump device for firmware-assisted system dump. The sysdumpdev command supports configuring an iSCSI logical volume as a dump device. In AIX V6.1, it was mandatory that this dump device be located on an iSCSI boot device.

AIX V7.1, firmware-assisted dump also supports dump devices located on arbitrary non-boot iSCSI disks. This allows diskless servers to dump to remote iSCSI disks using firmware-assisted dump. The iSCSI disks must be members of the root volume group.

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