blk_update_request: I/O error on NFS (was: [Xen-users] xen domU disk on nfs shared file)

[Wei Liu <wei.liu2@citrix.com>]

Drop xen-users@, CC xen-devel@ and blk maintainers, change title.

On Mon, Jan 11, 2016 at 03:08:24PM +0100, Kojedzinszky Richárd wrote:
> Dear all,
> 
> We are facing a regular lockup with our xen setup. We have an nfs share
> mounted on the xen dom0, where the vm images are served, and those files are
> given to xen domUs.
> 
> I was just preparing an experiment, where I created a 100G file on the host:
> # truncate -s 100G /srv/nfs/domU/disk2
> And after added this disk to the instance's configuration.
> 
> On the host this is the mountpoint:
> # mount|grep srv/xen
> 10.1.1.1:/mnt/main/vps on /srv/xen type nfs (rw,relatime,vers=3,rsize=16384,wsize=16384,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=10.1.1.1,mountvers=3,mountport=4045,mountproto=udp,local_lock=none,addr=10.1.1.1)
> 
> After starting the instance I partitioned the disk with gdisk, and created
> an xfs fs on it. While the fs has been created well, strange messages
> appeared on the console:
> 
> [   23.787504] blk_update_request: I/O error, dev xvdc, sector 2048
> [   23.788904] blk_update_request: I/O error, dev xvdc, sector 8390655
> [   23.789611] blk_update_request: I/O error, dev xvdc, sector 16779262
> [   23.790359] blk_update_request: I/O error, dev xvdc, sector 25167869
> [   23.791148] blk_update_request: I/O error, dev xvdc, sector 33556476
> [   23.791498] blk_update_request: I/O error, dev xvdc, sector 41945083
> [   23.791498] blk_update_request: I/O error, dev xvdc, sector 50333690
> [   23.791498] blk_update_request: I/O error, dev xvdc, sector 58722297
> [   23.791498] blk_update_request: I/O error, dev xvdc, sector 67110904
> [   23.791498] blk_update_request: I/O error, dev xvdc, sector 75499511
> 
> I dont think that this is normal. If I chose a local block device (probably
> lvm) for the domU, this does not appear.
> 
> The host is running xen-4.4 with 3.16.0-4-amd64 kernel (debian jessie
> stock), the domU is running 4.3.0-0.bpo.1-amd64 (jessie backport, 4.4.4).
> 
> I suspect those messages should not be there.
> 
> Regards,
> 
> Kojedzinszky Richárd
> Euronet Magyarorszag Informatika Zrt.

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