Re: RAID tuning?

[Adam Talbot <talbotx@comcast.net>]

I still have not figured out if "block" is per disk or per stripe?
My current array is rebuilding and states "64k chunk" is this a per disk
number or is that a functional stripe?

Nice scrip Gordon.  It turns out that I have build a script that does
the exact same thing.  I call I thrash_test.  Trying to take down the
array before it goes in to production. It is a very good test!

I ran hdpram -t last time the array was up. It states I am running at
about 200 MB/sec.  I will get you the real number when the array is done
rebuilding.  currently at 120min left...
 
Can any one give me more info on this error?  Pulled from
/var/log/messages.
"raid6: read error corrected!!"
-Adam




Gordon Henderson wrote:
> On Tue, 13 Jun 2006, Justin Piszcz wrote:
>
>   
>>     mkfs -t xfs -f -d su=128k,sw=14 /dev/md9
>>
>> Gordon, What speed do you get on your RAID, read and write?
>>
>> When I made my XFS/RAID-5, I accepted the defaults for the XFS filesystem
>> but used a 512kb stripe.  I get 80-90MB/s reads and ~39MB/s writes.
>>
>> On 5 x 400GB ATA/100 Seagates (on a regular PCI bus, max, 133mb/s)
>>     
>
> Standard Bonnie (which I find to be a crude, but reasonable test of overal
> throughput of a device - server has 1G of RAM)
>
> zem:/mounts/pdrive# bonnie -n0 -f -g0 -u0
> Using uid:0, gid:0.
> Writing intelligently...done
> Rewriting...done
> Reading intelligently...done
> start 'em...done...done...done...
> Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
>                     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
> zem              2G           195984  59 68699  31           217398  52  1028   3
> zem,2G,,,195984,59,68699,31,,,217398,52,1028.3,3,,,,,,,,,,,,,
>
>
> Other tests:
>
> zem:/mounts/pdrive# hdparm -T /dev/md9
> /dev/md9:
>  Timing cached reads:   3592 MB in  2.00 seconds = 1797.08 MB/sec
>
> zem:/mounts/pdrive# hdparm -t /dev/sda /dev/md9
> /dev/sda:
>  Timing buffered disk reads:  228 MB in  3.01 seconds =  75.87 MB/sec
> /dev/md9:
>  Timing buffered disk reads:  242 MB in  3.02 seconds =  80.14 MB/sec
>
> The server is some Dell 1U box with a single P4/HT processor and 1G of
> RAM. It has twin internal SCSI drives on a Fusion MPT driver, drives are
> using Linux s/w RAID-1, of course, and it has 2 external SCSI connectors
> (dual Adaptec controller) going to some big Dell 14-drive chasis with 7
> drives on each chain. I've not actually seen this box - I did the entire
> build remote with the aid of someone in-front of the box who loaded Debian
> on it under my instructions, until I could SSH into it and complete the
> process, and did the neccessary BIOS fiddling to make sure it would boot
> off the internal drives - it's in Califronia, US I'm in Devon, UK...
>
> Gordon
> -
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