On Thu, Jan 21, 2016 at 7:54 AM, Pavel Gashev <> wrote:

> Hello,
> First of all I would like to ask if anybody has an experience with using
> Microsoft NFS server as a storage domain.
I have used one as an ISO domain for years. It wasn't great, but it was
good enough. Never a data domain though

> The main issue with MS NFS is NTFS :) NTFS doesn't support sparse files.
> Technically it's possible by enabling NTFS compression but  it has bad
> performance on huge files which is our case. Also there is no option in
> oVirt web interface to use COW format on NFS storage domains.
> Since it looks like oVirt doesn't support MS NFS, I decided to migrate all
> my VMs out of MS NFS to another storage. And I hit a bug. Live storage
> migration *silently* *corrupts* *data* if you migrate a disk from MS NFS
> storage domain. So if you shutdown just migrated VM and check filesystem
> you find that it has a lot of unrecoverable errors.
> There are the following symptoms:
> 1. It corrupts data if you migrate a disk from MS NFS to Linux NFS
> 2. It corrupts data if you migrate a disk from MS NFS to iSCSI
> 3. There is no corruption if you migrate from Linux NFS to iSCSI and vice
> versa.
> 4. There is no corruption if you migrate from anywhere to MS NFS.
> 5. Data corruption happens after 'Auto-generated for Live Storage
> Migration' snapshot. So if you rollback the snapshot, you could see
> absolutely clean filesystem.
> 6. It doesn't depend on SPM. So it corrupts data if SPM is on the same
> host, or another.
> 7. There are no error messages in vdsm/qemu/system logs.
> Yes, of course I could migrate from MS NFS with downtime – it's not an
> issue. The issue is that oVirt does silently corrupt data under some
> circumstances.
> Could you please help me to understand the reason of data corruption?
> vdsm-4.17.13-1.el7.noarch
> qemu-img-ev-2.3.0-31.el7_2.4.1.x86_64
> libvirt-daemon-1.2.17-13.el7_2.2.x86_64
> ovirt-engine-backend-
> Thank you
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