RE: 3Ware 9550SX and latency/system responsiveness

["Ross S. W. Walker" <rwalker@xxxxxxxxxxxxx>]

Simon Banton wrote:
> 
> At 10:04 -0400 24/9/07, Ross S. W. Walker wrote:
> >How about trying your benchmarks with the 'disktest' utility from the
> >LTP (Linux Test Project),
> 
> Now fetched and installed - I'd be grateful for a suggestion as to an 
> appropriate disktest command line for a 4GB RAM twin CPU box with 
> 250GB RAID 1 array, because I think you had your tongue in your cheek 
> when you said:
> 
> >it is also a
> >lot easier to setup and use.

Ok, so maybe it's easy for me... I forget that nothing is easy the first
time using it.

Ok, so here is the command I would use:

Sequential reads:
disktest -B 4k -h 1 -I BD -K 4 -p l -P T -T 300 -r /dev/sdX

Sequential writes:
disktest -B 4k -h 1 -I BD -K 4 -p l -P T -T 300 -w /dev/sdX

Random writes:
disktest -B 4k -h 1 -I BD -K 4 -p r -P T -T 300 -r /dev/sdX

Random writes:
disktest -B 4k -h 1 -I BD -K 4 -p r -P T -T 300 -w /dev/sdX


Description of the options used:
-B 4k = 4k block ios
-h 1 = 1 second heartbeat
-I BD = block device, direct io
-K 4 = 4 threads, or 4 outstanding/overlapping ios, typical pattern
(use -K 1 for the raw performance of single drive, aka dd type output)
-p <l|r> = io type, l=linear, r=random
-P T = output metrics type "Throughput"
-T 300 = duration of test 300 seconds
-r = read
-w = write

These tests will run across the whole disk/partition and the write tests
WILL BE DESTRUCTIVE so be warned!

-Ross

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