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IBM AIX/UNIX system storage administration ksh/perl scripting

Thursday, May 22, 2008

Latest Set of General Purpose AIX v5.3 Tunables

Latest Set of General Purpose AIX v5.3 Tunables

Please ensure you test these first before implementing in production as your mileage may vary

no -p -o rfc1323=1
no -p -o sb_max=1310720
no -p -o tcp_sendspace=262144
no -p -o tcp_recvspace=262144
no -p -o udp_sendspace=65536
no -p -o udp_recvspace=655360
nfso -p -o rfc_1323=1
nfso -p -o nfs_socketsize=600000
nfso -p -o nfs_tcp_socketsize=600000

Memory Settings
vmo -p -o minperm%=5
vmo -p -o maxperm%=90
vmo -p -o maxclient%=90
vmo -p -o minfree=1000
vmo -p -o maxfree=1200
vmo -p -o lru_file_repage=0
vmo -p -o lru_poll_interval=10
Leave strict_maxperm and strict_maxclient at their defaults

IO Settings
Leave minpgahead and J2_minPageReadAhead at their defaults of 2
ioo -p -o j2_maxPageReadAhead=128
ioo -p -o maxpgahead=16
ioo -p -o j2_nBufferPerPagerDevice=1024
ioo -p -o hd_pbuf_cnt=1024
ioo -p -o numfsbufs=2048
ioo -p -o pv_min_pbuf=1024
#### this is the 5.3 value - below is the one for 5.2
### ioo -p -o pv_min_pbuf=1024

If doing lots of raw I/O you may want to change lvm_bufcnt
Default is 9
ioo -p -o lvm_bufcnt=12

Others left to default that you may want to tweak include:
ioo -p -o numclust=1
ioo -p -o j2_nRandomCluster=0
ioo -p -o j2_nPagesPerWriteBehindCluster=32
ioo -p -o j2_maxRandomWrite=32
ioo -p -o maxrandwrt=32

These are starting points only

Other areas to look at tuning:
Fiber cards
Check out max_xfer_size - 0x100000 is 16mb dma, 0x200000 is 128mb dma
For heavy I/O you may want to change this to 128mb
Check out queue_depth. If seeing sqfull on iostat -D then
increase queue_depth if your disk subsystem allows it

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