Jaqui's AIX Performance and Security Blog

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

2/8/2007 AIX v5.3 Links to get perfscript and instructions Script to gather data http://www.circle4.com/jaqui/perfdata53-latest.sh.txt Instructions for script and nmon http://www.circle4.com/jaqui/perf-script-instructions.txt

2/8/2007 AIX v5.3 Tunables Update When making tunable changes please be sure to test them first. 1. Please be careful when setting lru_file_repage. If you are asked to change this value from the default (which you should) please ensure you first set maxperm and maxclient back to 80% 2. I do want to mention that a couple of the parameters may not work well with certain workloads, specifically maxrandwrt and maxpgahead. The situation where I saw a problem was very application specific (Topform and Providex) but try it both ways. I normally set them for JFS and JFS2 as follows: ioo -p -o j2_maxPageReadAhead=128 ioo -p -o maxpgahead=16 ioo -p -o j2_maxRandomWrite=32 ioo -p -o maxrandwrt=32 However, you may be better to leave them at the defaults: ioo -p -o j2_maxPageReadAhead=128 ioo -p -o maxpgahead=8 ioo -p -o j2_maxRandomWrite=0 ioo -p -o maxrandwrt=0

2/8/2007 General Purpose AIX v5.2 at >ML4 Tunables Current recommended AIX v5.2 ML4 Performance Parameters: 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 Leave maxperm and maxclient at default of 80 Leave strict_maxperm and strict_maxclient at their defaults vmo -p -o minfree=960 vmo -p -o maxfree=1088 vmo -p -o lru_file_repage=0 vmo -p -o lru_poll_interval=10 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_maxRandomWrite=32 ioo -p -o maxrandwrt=32 ioo -p -o j2_nBufferPerPagerDevice=1024 ioo -p -o hd_pbuf_cnt=1024 #### this is the 5.3 value - above is the one for 5.2 ### ioo -p -o pv_min_pbuf=1024 ioo -p -o numfsbufs=2048 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 These are starting points only

2/8/2007 General Purpose AIX v5.3 Tunables Current recommended AIX v5.3 Performance Parameters: 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 Leave maxperm and maxclient at default of 80 Leave strict_maxperm and strict_maxclient at their defaults vmo -p -o minfree=960 vmo -p -o maxfree=1088 vmo -p -o lru_file_repage=0 vmo -p -o lru_poll_interval=10 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_maxRandomWrite=32 ioo -p -o maxrandwrt=32 ioo -p -o j2_nBufferPerPagerDevice=1024 ioo -p -o pv_min_pbuf=1024 ioo -p -o numfsbufs=2048 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 These are starting points only

Using and Obtaining nmon Nmon is available for AIX and Linux (x86 and Power) Download the latest nmon for AIX v5.3 from http://www-941.ibm.com/collaboration/wiki/display/WikiPtype/nmon You will need to gunzip it and untar it I untar it to /usr/local/perf Then run nmon_aix53 as follows: cd /usr/local/perf nmon_aix53 -fT -c 30 -s 240 This will cause nmon to run for about 2 hours gathering data - the output will be put in /usr/local/perf Once it is finished (check using ps -ef | grep nmon) then use nmon analyzer and MS Excel to analyze the output nmon analyser can be found at: http://www-128.ibm.com/developerworks/eserver/articles/nmon_analyser/index.html or http://www-941.haw.ibm.com/collaboration/wiki/display/WikiPtype/nmonanalyser You can find out more about nmon at Nigel Griffiths' online workshop at: http://www-941.ibm.com/collaboration/wiki/display/WikiPtype/nmon+Introduction+Workshop

Welcome to my Blog. As I have time I will put updates on various technical issues here for you to check out. If you have questions, feel free to email me and I will either answer them here or I will answer them via my column in IBM's Systems Magazine for pSeries (used to be eServer for UNIX),