suddenly slow writes on XFS Filesystem

[Stefan Priebe]

Am 06.05.2012 17:45, schrieb Stan Hoeppner:
> On 5/6/2012 5:33 AM, Martin Steigerwald wrote:
>> Am Sonntag, 6. Mai 2012 schrieb Stefan Priebe:
>>> It is a raid 10 of 20 SATA Disks and i can only write to them with
>>> about  700kb/s while doing random i/o. I tried vanilla Kernel 3.0.30
>>> and 3.3.4 - no difference. Writing to another partition on another xfs
>>> array works fine.
>>
>> Additionally what RAID is this? SoftRAID or some - which one? - hardware
>> RAID controller? And what disks are used, whats the rpm of these?
>
> I doubt much of this stuff matters.  Stefan's filesystem is 96% full,
> w/~200GB free.  This free space is likely heavily fragmented.  If he's
> doing allocation in this fragmented free space I'd think that would
> fully explain his write performance dropping off a cliff due to massive
> head seeking.
>
Thanks Stan that's it. After deleting 200GB-300GB it's running fine again.

What is the general recommandation of free space?

Greets Stefan