SSD optimizations

See http://tombuntu.com/index.php/2008/09/04/four-tweaks-for-using-linux-with-solid-state-drives/

put /tmp in RAM:

tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0

/boot, /home, /swap on Velociraptor /dev/sdd

/ on RevoDrive /dev/md0 (/dev/sda, /dev/sdb)

I don't know that this is optimal but it's what I used

mdadm --create --verbose /dev/md0 --level=0 --raid-devices=2 /dev/sda /dev/sdb
mke2fs -b 409 -E stride 16 /dev/md0

put noatime option in /etc/fstab

disable the elevator scheduler, put these in /etc/rc.local

echo noop > /sys/block/sda/queue/scheduler
echo noop > /sys/block/sdb/queue/scheduler

manage write caching via /etc/hdparm.conf

# SSD RevoDrive
/dev/sda {
	write_cache = off
}

/dev/sdb {
	write_cache = off
}

# Raptor drive
/dev/sdc {
	write_cache = on
}

# Caviar drive
/dev/sdd {
	write_cache = on
}

Test results

the new Black drive is faster than the Velociraptor. The SSD is FAST and the Green is slow. No surprises there. Tested with hdparm -t command.

# RevoDrive
Timing buffered disk reads:  1028 MB in  3.01 seconds = 341.87 MB/sec

bonnie++
Version  1.96       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
raven           16G  1958  99 498533  42 193488  24  4443  98 501475  27  6290 125
Latency              6425us     378ms   52859us    2402us    9032us    4884us
Version  1.96       ------Sequential Create------ --------Random Create--------
raven               -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16  7355  95 +++++ +++ +++++ +++  7916  94 +++++ +++ 24012  89
Latency               490us     113us      74us     265us      32us     763us

1.96,1.96,raven,1,1289707876,16G,,1958,99,498533,42,193488,24,4443,98,501475,27,6290,125,16,,,,,7355,95,+++++,+++,+++++,+++,7916,94,+++++,+++,24012,89,6425us,378ms,52859us,2402us,9032us,4884us,490us,113us,74us,265us,32us,763us

# Velociraptor
Timing buffered disk reads:  358 MB in  3.01 seconds = 118.84 MB/sec
bonnie++ -d /home/bwilson/foo
Version  1.96       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
raven           16G  1412  97 90887   7 44795   5  3581  97 111852   5 299.7   6
Latency              8841us     688ms    1184ms   17654us     349ms     142ms
Version  1.96       ------Sequential Create------ --------Random Create--------
raven               -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16   334   1 +++++ +++   472   1   332   1 +++++ +++   473   1
Latency               109ms     130us     124ms     354ms      35us     242ms
1.96,1.96,raven,1,1289708289,16G,,1412,97,90887,7,44795,5,3581,97,111852,5,299.7,6,16,,,,,334,1,+++++,+++,472,1,332,1,+++++,+++,473,1,8841us,688ms,1184ms,17654us,349ms,142ms,109ms,130us,124ms,354ms,35us,242ms

# Caviar Green
Timing buffered disk reads:  198 MB in  3.00 seconds =  65.97 MB/sec

# Caviar Black
Timing buffered disk reads:  442 MB in  3.01 seconds = 146.99 MB/sec