On 24/05/2016 8:24 PM, Kevin Lemonnier wrote:
So the VM were configured with cache set to none, I just tried with
cache=directsync and it seems to be fixing the issue. Still need to run
more test, but did a couple already with that option and no I/O errors.
Never had to do this before, is it known ? Found the clue in some old mail
from this mailing list, did I miss some doc saying you should be using
directsync with glusterfs ?
Interesting, I remember seeing some issues with cache=none on the
proxmox mailing list. I use writeback or default, which might be why I
haven't encountered theses issue. I suspect you would find writethrough
works as well.
From the proxmox wiki:
"/This mode causes qemu-kvm to interact with the disk image file or
block device with O_DIRECT semantics, so the host page cache is bypassed //
// and I/O happens directly between the qemu-kvm userspace buffers
and the storage device. Because the actual storage device may
report //
// a write as completed when placed in its write queue only, the
guest's virtual storage adapter is informed that there is a writeback
cache, //
// so the guest would be expected to send down flush commands as
needed to manage data integrity.//
// Equivalent to direct access to your hosts' disk, performance wise./"
I'll restore a test vm and try cache=none myself.
--
Lindsay Mathieson
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