FreeBSD 9.0 hangs on heavy I/O

[Kees Jan Koster]

Dear Gary,

>> # camcontrol devlist
>> <WDC WD740ADFD-00NLR1 20.07P20>    at scbus1 target 0 lun 0 (pass0,ada0)
>> <WDC WD740GD-00FLC0 33.08F33>      at scbus2 target 0 lun 0 (pass1,ada1)
>> <WDC WD740GD-00FLC0 33.08F33>      at scbus3 target 0 lun 0 (pass2,ada2)
>> <OCZ SUMMIT VBM1801Q>              at scbus4 target 0 lun 0 (pass3,ada3)
>> <PepperC Virtual Disc 1 0.01>      at scbus7 target 0 lun 0 (pass4,cd0)
>> <PepperC Virtual Disc 2 0.01>      at scbus8 target 0 lun 0 (pass5,cd1)
> 
> Check the SSD for its internal block size and make sure your filesystem
> and partitions are aligned with the disk block size.  Unless there
> is something wrong with your SATA controller I'd expect a lot more than
> 273 IOPS/sec and ~30MByte/sec from a SSD.


Thank you for suggesting this. However, I recently went through my file systems to fix disk alignment. I ended up aligning them to 1M blocks, which raised the throughput from 6M/s to about 60-80MB/s which is what I am seeing today.

# gpart show
...
=>       34  250069613  ada3  GPT  (119G)
         34       2014        - free -  (1M)
       2048  250067599     1  freebsd-ufs  (119G)

Do you think I need to revisit alignment?

--
Kees Jan

http://java-monitor.com/
kjkoster at kjkoster.org
+31651838192

Change is good. Granted, it is good in retrospect, but change is good.