XFS: Abysmal write performance because of excessive seeking (allocation groups to blame?)

[Joe Landman]

On 04/10/2012 10:02 AM, Stefan Ring wrote:
>> And is XFS aligned to the RAID 6?
>>
>> What does xfs_info display on it?
>
> Yes, it’s aligned.
>
> meta-data=/dev/mapper/vg_data-lvhome isize=256    agcount=4,
> agsize=73233656 blks
>           =                       sectsz=512   attr=2
> data     =                       bsize=4096   blocks=292934624, imaxpct=5
>           =                       sunit=8      swidth=32 blks
> naming   =version 2              bsize=4096   ascii-ci=0
> log      =internal               bsize=4096   blocks=143040, version=2
>           =                       sectsz=512   sunit=8 blks, lazy-count=1
> realtime =none                   extsz=4096   blocks=0, rtextents=0
>
> I changed the stripe size to 32kb in the meantime. This way, it
> performs slightly better.

try 128k to 512k for stripe size.  And try to increase your agcount by 
(nearly) an order of magnitude.


-- 
Joseph Landman, Ph.D
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