[ovirt-users] Storage slowly expanding

[Yaniv Kaul]

On Fri, Sep 1, 2017 at 6:49 PM, Jim Kusznir <jim at palousetech.com> wrote:

> Thank you!
>
> I created all the VMs using the sparce allocation method.  I wanted a
> method that would create disks that did not immediately occupy their full
> declared size (eg, allow overcommit of disk space, as most VM hard drives
> are 30-50% empty for their entire life).
>
> I kinda figured that it would not free space on the underlying storage
> when a file is deleted within the disk.  What confuses me is a disk that is
> only 30GB to the OS is using 53GB of space on gluster.  In my
> understanding, the actual on-disk usage should be limited to 30GB max if I
> don't take snapshots.  (I do like having the ability to take snapshots, and
> I do use them from time to time, but I usually don't keep the snapshot for
> an extended time...long enough to verify whatever operation I did was
> successful).
>
> I did find the "sparcify" command within ovirt and ran that; it reclaimed
> some space (the above example of the 30GB disk which is actually using 20GB
> inside the VM but was using 53GB on gluster shrunk to 50GB on gluster...But
> there's still at least 20GB unaccounted for there.
>
> I would love it if there was something I could do to reclaim the space
> inside the disk that isn't in use too (eg, get that disk down to just the
> 21GB that the actual VM is using).  If I change to virtio-scsi (its
> currently just "virtio"), will that enable the DISCARD support, and is
> Gluster a supported underlying storage?
>

Especially if you don't use snapshots, I think the default of raw-sparse is
the way to go for you. It allocates the full disk space, but does not
occupy it. So it's not thin provisioned, but sparsely provisioned.

I remember Gluster supporting DISCARD.
Y.

>
> Thanks!
> --Jim
>
> On Fri, Sep 1, 2017 at 5:45 AM, Yaniv Kaul <ykaul at redhat.com> wrote:
>
>>
>>
>> On Fri, Sep 1, 2017 at 8:41 AM, Jim Kusznir <jim at palousetech.com> wrote:
>>
>>> Hi all:
>>>
>>> I have several VMs, all thin provisioned, on my small storage
>>> (self-hosted gluster / hyperconverged cluster).  I'm now noticing that some
>>> of my VMs (espicially my only Windows VM) are using even MORE disk space
>>> than the blank it was allocated.
>>>
>>> Example: windows VM: virtual size created at creation: 30GB (thin
>>> provisioned).  Actual disk space in use: 19GB.  According to the storage ->
>>> Disks tab, its currently using 39GB.  How do I get that down?
>>>
>>> I have two other VMs that are somewhat heavy DB load (Zabbix and Unifi);
>>> both of those are also larger than their created max size despite disk in
>>> machine not being fully utilized.
>>>
>>> None of these have snapshots.
>>>
>>
>> How come you have qcow2 and not raw-sparse, if you are not using
>> snapshots? is it a VM from a template?
>>
>> Generally, this is how thin provisioning works. The underlying qcow2
>> doesn't know when you delete a file from within the guest - as file
>> deletion is merely marking entries in the file system tables as free, not
>> really doing any deletion IO.
>> You could run virt-sparsify on the disks to sparsify them, which will, if
>> the underlying storage supports it, reclaim storage space.
>> You could use IDE or virtio-SCSI and enable DISCARD support, which will,
>> if the underlying storage supports it, reclaim storage space.
>>
>> Those are not exclusive, btw.
>> Y.
>>
>>
>>> How do I fix this?
>>>
>>> Thanks!
>>> --Jim
>>>
>>> _______________________________________________
>>> Users mailing list
>>> Users at ovirt.org
>>> http://lists.ovirt.org/mailman/listinfo/users
>>>
>>>
>>
>
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