Wednesday 5 May 2010

IBM pSeries (AIX) to Sun StorageTek 2540 - Part 2

The saga continues...

At the end of my previous port, the SAN LUN was being successfully seen by AIX as a single device using the Cambex driver.

With the multipathing fixed, it was time to build some WPARs. Everything went smoothly until we rebooted. At which point, hdisk10 was visible but I could no longer see the logical volumes on the disk. Furthermore, I couldn't activate the volume group I'd created "wparvg", getting the message:

bash-3.2# varyonvg wparvg
0516-013 varyonvg: The volume group cannot be varied on because there are no good copies of the descriptor area.

To cut a long story short (that primarily consists of me rebooting, removing the device in smit and running cfgmgr is various combinations), the Cambex install (/usr/lpp/cbxdpf) includes some useful commands. Running the dpfinfo command showed that hdisk10 was configured in the following way:

=== /usr/lpp/cbxdpf/dpfutil listall ===
# Device Active Standby
hdisk10 cbx1 (fscsi0 0x040200,1) cbx0 (fscsi0 0x030200,1)

This means that it's using path cbx1 as its active path, with cbx0 as the failover path. Some exploring with the dpfutil command showed it supports the following options:

dpfutil []
Commands may be abbreviated:
HELP - Display this message
LISTALL - List devices and path configuration
ACTIVATE [cbxN] - Manually switch virtual disk to path [cbxN]
VARYOFFLINE [cbxN] - Mark path [cbxN] unavailable
VARYONLINE [cbxN] - Mark path [cbxN] available
MARKFORDELETE [cbxN] - Force path off even if open (may crash)
LIST_HBAS - List HBAs with DPF paths
HBA_SET_WWN [cbxN] [no|yes] - Set WWN preferred path
TARGET_SET_WWN [cbxN] [yes|no] - Set target preferred path

I tried to manually switch over the paths:

bash-3.2# ./dpfutil activate cbx0
bash-3.2# ./dpfutil listall
# Device Active Standby
hdisk10 cbx0 (fscsi0 0x030200,1) cbx1 (fscsi0 0x040200,1)

With this done, I then tried the varyonvg again:

bash-3.2# varyonvg wparvg
bash-3.2# lsvg wparvg
VOLUME GROUP: wparvg VG IDENTIFIER: 00048ada0000d3000000012865034072
VG STATE: active PP SIZE: 256 megabyte(s)
VG PERMISSION: read/write TOTAL PPs: 999 (255744 megabytes)
MAX LVs: 256 FREE PPs: 979 (250624 megabytes)
LVs: 2 USED PPs: 20 (5120 megabytes)
OPEN LVs: 0 QUORUM: 2 (Enabled)
MAX PPs per VG: 32512
MAX PPs per PV: 1016 MAX PVs: 32
LTG size (Dynamic): 1024 kilobyte(s) AUTO SYNC: no
HOT SPARE: no BB POLICY: relocatable


Not sure what this says about the failover capabilities of the driver... It appears that when the VG is active, manually failing over the paths works okay and the VG remains active.

Fortunately this isn't a mission critical production box (it's a development compile box for porting our code from Solaris to AIX).

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