[ovirt-users] NFS and pass discards\unmap question

[Yaniv Kaul]

On Thu, Feb 2, 2017 at 11:45 PM, Sergey Kulikov <serg_k at msm.ru> wrote:

>
> I've upgraded to 4.1 release, it have great feature "Pass discards", that
> now can be used without vdsm hooks,
> After upgrade I've tested it with NFS 4.1 storage, exported from netapp,
> but unfortunately found out, that
> it's not working, after some investigation, I've found, that NFS
> implementation(even 4.1) in Centos 7
> doesn't support sparse files and fallocate(FALLOC_FL_PUNCH_HOLE), that
> quemu uses for file storage, it was
> added only in kernel 3.18, and sparse files is also announced feature of
> upcoming NFS4.2,
> sparsify also not working on this data domains(runs, but nothing happens).
>
> This test also shows, that FALLOC_FL_PUNCH_HOLE not working, it was
> executed on centos ovirt host with mounted nfs share:
> # truncate -s 1024 test1
> # fallocate -p -o 0 -l 1024 test1
> fallocate: keep size mode (-n option) unsupported
>
> Is there any plans to backport this feature to node-ng, or centos? or we
> should wait for RHEL 8?
>

Interesting, I was under the impression it was fixed some time ago, for
7.2[1] (kernel-3.10.0-313.el7)
Perhaps you are not mounted with 4.2?

Y.
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1079385


> NFS is more and more popular, so discards is VERY useful feature.
> I'm also planning to test fallocate on latest fedora with 4.x kernel and
> mounted nfs.
>
> Thanks for your work!
>
> --
>
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