Software RAID5 archived ~37 MB/sec resync speed with two pieces of 3ware 9550SX-8LP

# mdadm -Cv /dev/md7 -l5 -n15 -x1 -c128 /dev/sd[c-r]1
Personalities : [raid1] [raid5]
md7 : active raid5 sdq1[15] sdr1[16](S) sdp1[13] sdo1[12] sdn1[11] sdm1[10] sdl1[9] sdk1[8] sdj1[7] sdi1[6] sdh1[5] sdg1[4] sdf1[3] sde1[2] sdd1[1] sdc1[0]
4102468608 blocks level 5, 128k chunk, algorithm 2 [15/14] [UUUUUUUUUUUUUU_]
[>....................] recovery = 0.6% (1908296/293033472) finish=131.1min speed=36998K/sec

3ware 9000 Storage Controller device driver for Linux v2.26.04.006.
Firmware FE9X 3.01.01.028, BIOS BE9X 3.01.00.024.

Setting 'max_queue' options for sx8.ko increases RAID5 recovery speed to ~23 MB/sec

Unload sx8 module. Add
options sx8 max_queue=24
to /etc/modules.conf and reload sx8. Now the recovery speed with a single adaptor and 8 drives is increased to 23000K/sec.

The effect of max_queue=32 has not much difference but in the comment of sx8.c version 1.0 it is claimed that problems seem to occur when the value exceeds ~30.

Thanks to Jeff Garzik's ultra-prompt reply in five minutes.

Linux software RAID5 using sx8.c driver = only ~9000 K/sec recovery speed......

Kernel 2.6.14.2 SMP, sx8.c version 1.0

mdadm -Cv /dev/md7 -l5 -n7 -x1 /dev/sx8/[0-7]p1 -c 128



And if two SX8 adapters are used, raid5 recovery speed dropped under 500 K/sec if more than 8 drives are included.