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On Thu, Jan 21, 2016 at 7:54 AM, Pavel Gashev <Pax(a)acronis.com> 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-3.6.1.3-1.el7.centos.noarch
Thank you
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