6.11.2013 14:33, Jacob Yundt kirjoitti: > On Tue, Nov 5, 2013 at 10:56 PM, Bharata B Rao <bharata.rao at gmail.com> wrote: >> >> My below mail didn't make it to the list, hence resending... >> >> On Tue, Nov 5, 2013 at 8:04 PM, Bharata B Rao <bharata at linux.vnet.ibm.com> wrote: >>> >>> On Wed, Oct 30, 2013 at 11:26:48PM +0530, Bharata B Rao wrote: >>>> On Tue, Oct 29, 2013 at 1:21 PM, Anand Avati <avati at gluster.org> wrote: >>>> >>>>> 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). >>>>> >>>>> 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. >>>>> >>>>> Copying Bharata to check if he has other solutions in mind. >>>>> >>>> >>>> I see alignment issues and subsequent QEMU failure (pread() failing with >>>> EINVAL) when I use a file from XFS mount point (with sectsz=4k) as a virtio >>>> disk with cache=none QEMU option. However this failure isn't seen when I >>>> have sectsz=512. And all this is w/o gluster. So there seems to be some >>>> alignment issues even w/o gluster, I will debug more and get back. >>> >>> I gather that QEMU block layer and SeaBIOS don't yet support 4k sectors. >>> So this is not a QEMU-GlusterFS specific issue. >>> >>> You could either not use cache=none option which results in O_DIRECT >>> or use the below something like below which explicitly sets the sector size >>> and min io size for the guest. >>> >>> -drive file=/mnt/xfs.img,if=none,cache=none,format=raw,id=mydisk -device virtio-blk,drive=mydisk,logical_block_size=4096,physical_block_size=4096,min_io_size=4096 >>> >>> Ref: https://bugzilla.redhat.com/show_bug.cgi?id=997839 >>> >>> Regards, >>> Bharata. >>> > > > Bharata- > Thanks for the update on this. I'm going to give these qemu args a > try and see what happens. > > On a side-note, I can't believe more users aren't running into this > issue. I assumed (perhaps incorrectly) that most modern drives were > using 4K sectors. > > -Jacob Jacob, are you using xfs on top of HDD or are you using somekind of RAID? We have disks with 4K sectors and we are using those in RAID-6 setup with LSI Megaraid controller. We haven't run into these issues and I wasn't able to reproduce it. I did only very quick tests tho, so it may be that I have missed something. -samuli