2120S Stripe - abysmal performance

[Jens Schweikhardt]

hello, world\n

I hoped that my new Adaptec 2120S U320 RAID in my new Supermicro P4SCT
board with 64bit/66MHz PCI would turn my disk IO into a desktop blitz,
but the opposite has happened. While my old ASUS A7N8X with vinum would
read 100MB/s from 2 Fujitsu MAP3367 connected to an 29160, I get only
29MB/sec from the stripe built with the 2120S (as measured with dd to
/dev/null).

What I have done so far:
o have reset the 2120S config to factory defaults.
o set the transfer speed to U160 and disabled "packetized" because
  I could not low level format the drives otherwise. Until that point
  I had a lot of trouble even getting the 2120S to boot its controller
  kernel. Effect has been seemingly endless (5min) twirling baton.
o low level formatted both MAPs, initialized them and then built the
  stripe with 64kb stripe size.
o I have enabled caching in both directions.

The dmesg says
schweikh at hal9000:~ $ dmesg|grep aac
aac0: <Adaptec SCSI RAID 2120S> mem 0xe8000000-0xebffffff irq 9 at device 1.0 on pci3
aac0: Reserved 0x4000000 bytes for rid 0x10 type 3 at 0xe8000000
aac0: [FAST]
aac0: i960RX 100MHz, 48MB cache memory, optional battery present
aac0: Kernel 4.0-0, Build 6011, S/N ba12c0
aac0: Supported Options=1f7e<CLUSTERS,WCACHE,DATA64,HOSTTIME,RAID50,WINDOW4GB,SOFTERR,NORECOND,SGMAP64,ALARM,NONDASD>
aacd0: <RAID 0 (Stripe)> on aac0
aacd0: 69997MB (143354880 sectors)

Any enlightenment on how to improve disk io greatly appreciated.


Regards,

	Jens
-- 
Jens Schweikhardt http://www.schweikhardt.net/
SIGSIG -- signature too long (core dumped)