On Sun, May 06, 2012 at 09:25:10PM +0200, Stefan Priebe wrote: > 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? Depends on the size of the filesystem. If you've got a 500TB filesystem, then running at 98% full (10TB of free space) is not going to be a big deal. But running at 98% full on a 5TB volume is a big deal because there is relatively little freespace per AG and it will get rapidly fragmented. So for a 5TB volume, I' say don't run sustained operations at over 90% full. Going above this temporarily won't be a problem, but staying at >95% full will definitely cause accelerated aging of the filesystem. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
