Performance improvement for FASTt

This info is generally applicable to AIX systems using FAStT storage and is thought to improve performance. Some of these may be outdated, investigate before using.

FC adapter attribute changes:

lg_term_dma from 0x200000 to 0x1000000 – (from 2 MB to 16 MB)

lsattr -El fcs0
chdev -l fcs0 -a lg_term_dma=0x1000000 -P
cfgmgr
lsattr -El fcs0

num_cmd_elems from 200 to 1024

lattr -El fcs0
chdev -l fcs0 -a num_cmd_elems=1024 -P
cfgmgr
lsattr -El fcs0

DAR attribute changes:

load_balancing – IBM recommends against using load balancing in the DAR driver. Use with caution:

lsattr -El dar0
chdev -l dar0 -a load_balancing=yes
lsattr -El dar0

Setting autorecovery

lsattr -El dar0
chdev -l dar0 -a autorecovery=yes
lsattr -El dar0

hdisk attribute changes: [VG must be varied-off]

queue_depth from the default to 16

lsattr -El hdisk
chdev -l hdiskX queue_depth=16
lsattr -El hdisk

prefetch_mult from 0 to 8

lsattr -El hdisk
chdev -l hdiskXX prefetch_mult=8
lsattr -El hdisk

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