[Gluster-devel] IO errors when booting VM images on gluster volume via FUSE mount

[Jules Wang]

hi, Anand:
   Another question on "writeback" is: I observe disk performance boost(40x)(using IOMeter in VM) when setting cache=writeback in comparsion with cache=none or writethrough. 
   Do you have any ideas about that? :-)


Best Regards.


Jules Wang

 


At 2012-08-07 15:10:30,"Anand Avati" <anand.avati at gmail.com> wrote:
cache=writeback should not be necessary (including disabling write-behind). This is clearly a bug. We are looking into it.


On Mon, Aug 6, 2012 at 11:51 PM, Jules Wang <lancelotds at 163.com> wrote:

Bharata:
   Alternatively,You could add ",cache=writeback" after "if=virtio".
   Good Luck.


Best Regards.
Jules Wang



At 2012-08-07 14:29:38,"Bharata B Rao" <bharata.rao at gmail.com> wrote:
>Hi,
>
>With latest QEMU and latest gluster git, I observe guest root
>filesystem corruption when the VM boots.
>
>QEMU command line I am using is this:
>qemu-system-x86_64 --enable-kvm --nographic -m 1024 -smp 4 -drive
>file=/mnt/F17,if=virtio -net nic,model=virtio -net user -redir
>tcp:2000::22
>
>Gluster volume is mounted in this manner:
>glusterfs -s bharata --volfile-id=test -L DEBUG -l glusterfs.log /mnt
>
>I see IO errors like this when VM boots:
>[    1.698583] end_request: I/O error, dev vda, sector 9680896
>[    1.699328] Buffer I/O error on device vda3, logical block 1081344
>[    1.699328] lost page write due to I/O error on vda3
>[    1.706644] end_request: I/O error, dev vda, sector 1030144
>[    1.707630] Buffer I/O error on device vda3, logical block 0
>[    1.707630] lost page write due to I/O error on vda3
>[    1.718671] dracut:
>/dev/disk/by-uuid/d29b972f-3568-4db6-bf96-d2702ec83ab6: clean,
>21999/623392 files, 796916/2492672 blocks
>[    1.723455] dracut: Remounting
>/dev/disk/by-uuid/d29b972f-3568-4db6-bf96-d2702ec83ab6 with -o ro
>
>VM eventually comes up with RO rootfs. Shutdown path sees these kinds of error:
>
>[   16.034271] EXT4-fs (vda3): previous I/O error to superblock detected
>[   16.041699] end_request: I/O error, dev vda, sector 1030144
>[   16.042679] EXT4-fs error (device vda3): ext4_remount:4418: Abort
>forced by user
>[   16.046465] EXT4-fs (vda3): re-mounted. Opts: (null)
>
>Full glusterfs log is too big to go with this mail. I can see this
>kind of errors:
>
>[2012-08-07 05:56:29.598636] T [io-cache.c:128:ioc_inode_flush]
>0-test-io-cache: locked inode(0xd2d2c0)
>[2012-08-07 05:56:29.598642] T [io-cache.c:132:ioc_inode_flush]
>0-test-io-cache: unlocked inode(0xd2d2c0)
>[2012-08-07 05:56:29.598651] T [fuse-bridge.c:2113:fuse_writev_cbk]
>0-glusterfs-fuse: 319: WRITE => 4096/4096,4956618752/10737418240
>[2012-08-07 05:56:29.598749] T [fuse-bridge.c:2293:fuse_fsync_resume]
>0-glusterfs-fuse: 320: FSYNC 0xd6f060
>[2012-08-07 05:56:29.598845] W [write-behind.c:2809:wb_fsync]
>0-test-write-behind: write behind wb_inode pointer is not stored in
>context of inode(0x7f9cb1eab0c0), returning EBADFD
>[2012-08-07 05:56:29.598858] W [fuse-bridge.c:1063:fuse_err_cbk]
>0-glusterfs-fuse: 320: FSYNC() ERR => -1 (File descriptor in bad
>state)
>[2012-08-07 05:56:29.605831] T [fuse-bridge.c:2154:fuse_write_resume]
>0-glusterfs-fuse: 322: WRITE (0xd6f060, size=4096, offset=527433728)
>
>Just to clarify, I am not using GlusterFS block backend in QEMU (via
>libgfapi) here but instead using it with normal FUSE mount.
>
>Regards,
>Bharata.
>-- 
>http://bharata.sulekha.com/blog/posts.htm, http://raobharata.wordpress.com/


>
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