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On 3 Jul 2016 1:34 p.m., "Stefan Ring" <stefanrin@xxxxxxxxx> wrote:
>
> On Sat, Jul 2, 2016 at 10:52 AM, Nick Fisk <friskyfisk10@xxxxxxxxxxxxxx> wrote:
> > Hi, hope someone can help me here.
> >
> > I'm exporting some XFS fs's to ESX via NFS with the sync option enabled. I'm
> > seeing really heavy fragmentation when multiple VM's are copied onto the
> > share at the same time. I'm also seeing kmem_alloc failures, which is
> > probably the biggest problem as this effectively takes everything down.
> >
>
> The same thing happens with MySQL's InnoDB files if O_DIRECT is in use.
>
> The kmem_alloc failure taking everything down is most likely a result
> of you calling xfs_bmap on these files and does not happen during
> normal use. I've had the same experience some time ago.
Unfortunately this did happen during normal use. It occurred over night after kicking a bunch copies off. Something like 5 million extents for 10-20 files. I suspect as suggested, it's to do with memory fragmentation.
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