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Re: mkfs options for a 16x hw raid5 and xfs (mostly large files)

To: linux-xfs@xxxxxxxxxxx
Subject: Re: mkfs options for a 16x hw raid5 and xfs (mostly large files)
From: Ralf Gross <Ralf-Lists@xxxxxxxxxxxx>
Date: Wed, 26 Sep 2007 10:23:22 +0200
In-reply-to: <Pine.LNX.4.64.0709251938400.7763@xxxxxxxxxxxxxxxx>
References: <498689.78850.qm@xxxxxxxxxxxxxxxxxxxxxxxxxxx> <Pine.LNX.4.64.0709251938400.7763@xxxxxxxxxxxxxxxx>
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Justin Piszcz schrieb:
> 
> 
> On Tue, 25 Sep 2007, Bryan J. Smith wrote:
> 
> >Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> wrote:
> >>Just out of curisosity have you tried SW RAID5 on this array?
> >>Also what do you get if you use RAID0 (hw or sw)?
> >
> >According to him, if I read it correclty, it is an external FC RAID-5
> >chassis.  I.e., all of the logic is in the chassis.  So your question
> >is N/A.
> >
> >Although I'm more than ready to be proven incorrect.
> >
> >Furthermore, what benchmark do you use?  If dd on the volume itself,
> >software RAID wins, hands down.  Doesn't matter what size you give
> >it, it literally copies (and doesn't recalculate) the parity.  It's
> >the rawest form of non-blocking I/O, and uses virtually no system
> >interconnect to the CPU (just pushes disk-mem-disk).
> 
> bonnie++, iozone, etc..
> 
> all show ~430-460 MiB/s write and ~550 MiB/s read

I'm happy :) I was able to boost the read performance by setting 

blockdev --setra 16384 /dev/sdc

I knew this parameter is neccessary for 3ware controllers, but I
haven't noticed any difference with areca controllers or ext. raids yet.

The write performance may not be ideal, but these read numbers makes much
more sense now because the FC controller is the limiting factor.

Sequential Reads
File  Blk   Num                   Avg      Maximum      Lat%     Lat%    CPU
Size  Size  Thr   Rate  (CPU%)  Latency    Latency      >2s      >10s    Eff
----- ----- ---  ------ ------ --------- -----------  -------- -------- -----
20000  4096    1  391.20 50.24%     0.019       43.01   0.00000  0.00000   779
20000  4096    2  387.79 92.22%     0.040      278.71   0.00000  0.00000   420

Random Reads
File  Blk   Num                   Avg      Maximum      Lat%     Lat%    CPU
Size  Size  Thr   Rate  (CPU%)  Latency    Latency      >2s      >10s    Eff
----- ----- ---  ------ ------ --------- -----------  -------- -------- -----
20000  4096    1    2.87 0.698%     2.720       27.47   0.00000  0.00000   411
20000  4096    2    4.37 2.013%     3.473       47.35   0.00000  0.00000   217

Sequential Writes
File  Blk   Num                   Avg      Maximum      Lat%     Lat%    CPU
Size  Size  Thr   Rate  (CPU%)  Latency    Latency      >2s      >10s    Eff
----- ----- ---  ------ ------ --------- -----------  -------- -------- -----
20000  4096    1  189.23 42.73%     0.029     5670.66   0.00014  0.00000   443
20000  4096    2  173.92 84.93%     0.064     4590.56   0.00029  0.00000   205

Random Writes
File  Blk   Num                   Avg      Maximum      Lat%     Lat%    CPU
Size  Size  Thr   Rate  (CPU%)  Latency    Latency      >2s      >10s    Eff
----- ----- ---  ------ ------ --------- -----------  -------- -------- -----
20000  4096    1    1.85 0.662%     0.011        0.05   0.00000  0.00000   279
20000  4096    2    1.68 0.772%     0.012        0.05   0.00000  0.00000   217




Ralf


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