<div dir="ltr">Looks like what is happening is that qemu performs ioctls() on the backend to query logical_block_size (for direct IO alignment). That works on XFS, but fails on FUSE (hence qemu ends up performing IO with default 512 alignment rather than 4k).<div>
<br></div><div>Looks like this might be something we can enhance gluster driver in qemu. Note that glusterfs does not have an ioctl() FOP, but we could probably wire up a virtual xattr call for this purpose.</div><div><br>
</div><div>Copying Bharata to check if he has other solutions in mind.</div><div><br></div><div>Avati</div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Oct 29, 2013 at 12:13 AM, Anand Avati <span dir="ltr"><<a href="mailto:avati@gluster.org" target="_blank">avati@gluster.org</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">What happens when you try to use KVM on an image directly on XFS, without involving gluster?<span class="HOEnZb"><font color="#888888"><div>
<br></div><div>Avati</div></font></span></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><br><div class="gmail_quote">On Sun, Oct 27, 2013 at 5:53 PM, Jacob Yundt <span dir="ltr"><<a href="mailto:jyundt@gmail.com" target="_blank">jyundt@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I think I finally made some progress on this bug!<br>
<br>
I noticed that all disks in my gluster server(s) have 4K sectors.<br>
Using an older disk with 512 byte sectors, I did _not_ get any errors<br>
on my gluster client / KVM server. I switched back to using my newer<br>
4K drives and manually set the XFS sector size (sectsz) to 512. With<br>
the manually set sector size of 512, everything worked as expected.<br>
<br>
I think I might be hitting some sort of qemu/libvirt bug. However,<br>
all of the bugs I found that sound similar[1][2] have already been<br>
fixed in RHEL6.<br>
<br>
Anyone else using XFS backed bricks on 4K sector drives to host KVM<br>
images in RHEL6?<br>
<br>
-Jacob<br>
<br>
[1] <a href="https://bugzilla.redhat.com/show_bug.cgi?id=608548" target="_blank">https://bugzilla.redhat.com/show_bug.cgi?id=608548</a><br>
[2] <a href="https://bugzilla.redhat.com/show_bug.cgi?id=748902" target="_blank">https://bugzilla.redhat.com/show_bug.cgi?id=748902</a><br>
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