Mon, 03 Dec 2007

Latest Set of General Purpose AIX v5.3 Tunables

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

Network
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
hdisks
	Check out queue_depth.  If seeing sqfull on iostat -D then
	increase queue_depth if your disk subsystem allows it