adaptec 2120S report

[Andrew Snow]

After my failure to get the Serveraid-5i working, I have put in an 
Adaptec 2120S. This card has very similar features to the Serveraid 
card, with the addition that it actually works in FreeBSD.

After a couple of days of testing I can recommend this card.  I have 
6x36GB IBM 10krpm drives running in RAID 50 configuration with FreeBSD 
5.1-REL.  The only downside was I cannot get it working at Ultra-320 
with this IBM x345 hotswap backplane, but it is working great at Ultra-160.

With my configuration, a quick test of file system sequential access 
speed shows reads at 47mb/s and writes at 27mb/s.  The good news is, 
while the array is degraded and rebuilding, read is 10mb/s and write is 
6mb/s which is still quite respectable. The box still feels fast enough 
while the array is rebuilding. The downside is rebuilding the RAID5 
containers took 5 hours - each.

Two problems with this controller in FreeBSD 5.1:

1. FreeBSD won't boot while the array is rebuilding. It hangs after 
detecting aacd0.  I did not try waiting 5 hours to see if it continued 
after the array rebuild finished.
Workaround is to only hot swap drives while FreeBSD is running, and do 
not reboot until rebuild is finished.  Alternatively, boot into the 
controller BIOS and wait for rebuild to finish there.

2. I could not get SMP kernel to work - its a Xeon 2.6ghz supporting 
hyperthreading. SMP worked without the controller, but hangs during boot 
with the controller.  Luckily this is not a big problem for us as we 
only need a single CPU and hyperthreading is of minor/dubious advantage.
Workaround is to simply not use an SMP kernel.

Other than that, it seems to be working very nicely.  I look forward to 
seeing the Serveraid / ips driver issues resolved in 5.2...


- Andrew