Re: 3ware bad write speed.

Thanks! Joshua:
    We are runing oracle on rehat advanced server 2.1. Oracle only certified
this version of redhat with ext2. That' why we could not switch to another
linux
or file system. :-(

Donghui

> The card is capable of much better than that.  Here are my numbers from a
> 7 disk RAID5 array (8th is a hot spare) on a 7500-8 board:
>
> Sequential Writes
>                               File  Blk   Num                   Avg
> Maximum
>       Lat%     Lat%    CPU
> Identifier                    Size  Size  Thr   Rate  (CPU%)  Latency
> Latency
>       >2s      >10s    Eff
> ---------------------------- ------ ----- ---  ------ ------ ---------
> ---------
> --  -------- -------- -----
> 2.4.18-17SGI_XFS_1.2pre3smp   4096  4096    1   49.50 20.52%     0.068
> 2915.
> 71   0.00124  0.00000   241
> 2.4.18-17SGI_XFS_1.2pre3smp   4096  4096    2   45.17 23.21%     0.141
> 7873.
> 45   0.00343  0.00000   195
> 2.4.18-17SGI_XFS_1.2pre3smp   4096  4096    4   39.98 23.29%     0.335
> 13338.
> 23   0.00887  0.00010   172
> 2.4.18-17SGI_XFS_1.2pre3smp   4096  4096    8   39.23 24.30%     0.631
> 7887.
> 96   0.01535  0.00000   161
>
> Obviously I've got more spindles, but your speeds shouldn't be *that* bad.
> Some things to check:
>
> 1) You said latest drivers, but make sure that you upgraded everything --
> a driver set from 3ware is driver+firmware+3dm.  Specifically, make sure
> your firmware is up to date with your driver.
>
> 2) Make sure that your kernel supports HIGHIO.  I don't know if that
> enterprise kernel does (do you need to run it?), but it makes a *big*
> difference.  The latest 3ware drivers support HIGHIO, but the kernel needs
> to as well.
>
> 3) Make sure your drives are listed as compatible.
>
> 4) Try a different FS.  The numbers above are with XFS -- with ext3 I was
> getting write speeds of only half that (at best).
>
> Good luck.
>
> --
> Joshua Baker-LePain
> Department of Biomedical Engineering
> Duke University
>
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