[PVE-User] Storage migration issue with thin provisionning SAN storage

[Dhaussy Alexandre]

Hello Brian,

Thanks for the tip, it may be my last chance solution..

Fortunatly i kept all original disk files on a NFS share, so i 'm able 
to rollback and re-do the migration...if manage to make qemu mirroring 
work with sparse vmdks..


Le 03/10/2016 à 21:11, Brian :: a écrit :
> Hi Alexandre,
>
> If guests are linux you could try use the scsi driver with discard enabled
>
> fstrim -v / then may make the unused space free on the underlying FS then.
>
> I don't use LVM but this certainly works with other types of storage..
>
>
>
>
>
> On Mon, Oct 3, 2016 at 5:14 PM, Dhaussy Alexandre
> <ADhaussy at voyages-sncf.com> wrote:
>> Hello,
>>
>> I'm actually migrating more than 1000 Vms from VMware to proxmox, but i'm hitting a major issue with storage migrations..
>> Actually i'm migrating from datastores VMFS to NFS on VMWare, then from NFS to LVM on Proxmox.
>>
>> LVMs on Proxmox are on top thin provisionned (FC SAN) LUNs.
>> Thin provisionning works fine on Proxmox newly created VMs.
>>
>> But, i just discovered that when using qm move_disk to migrate from NFS to LVM, it actually allocates all blocks of data !
>> It's a huge problem for me and clearly a nogo... as the SAN storage arrays are filling up very quickly !
>>
>> After further investigations, in qemu & proxmox... I found in proxmox code that qemu_drive_mirror is called with those arguments :
>>
>> (In /usr/share/perl5/PVE/QemuServer.pm)
>>
>>     5640 sub qemu_drive_mirror {
>> .......
>>     5654     my $opts = { timeout => 10, device => "drive-$drive", mode => "existing", sync => "full", target => $qemu_target };
>>
>> If i'm not wrong, Qemu supports "detect-zeroes" flag for mirroring block targets, but proxmox does not use it.
>> Is there any reason why this flag is not enabled during qemu drive mirroring ??
>>
>> Cheers,
>> Alexandre.
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