[CentOS-virt] proper way to snapshot

aurfalien aurfalien at gmail.com
Thu Apr 26 17:48:01 EDT 2012


On Apr 26, 2012, at 2:24 PM, Nux! wrote:

> On 26.04.2012 19:21, aurfalien wrote:
>> On Apr 26, 2012, at 2:15 PM, Nux! wrote:
>> 
>>> On 26.04.2012 19:12, aurfalien wrote:
>>>> On Apr 26, 2012, at 1:54 PM, Nux! wrote:
>>>> 
>>>>> On 26.04.2012 18:23, aurfalien wrote:
>>>>>> Hi,
>>>>>> 
>>>>>> While there are a few howtos floating around, what is the 
>>>>>> standard
>>>>>> way to snapshot guests?
>>>>>> 
>>>>>> I went through and converted from raw to pre allocated meta data
>>>>>> qcow2 images for this purpose.
>>>>>> 
>>>>>> Some howtos suggest to do an xml snapshot file as so;
>>>>>> 
>>>>>> <domainsnapshot>
>>>>>> <name>UbuntuServer_10.10-16032011</name>
>>>>>> <description>Snapshot of OS install and updates</description>
>>>>>> </domainsnapshot>
>>>>>> 
>>>>>> And then to run as so;
>>>>>> 
>>>>>> virsh snapshot-create UbuntuServer_10.10 
>>>>>> UbuntuServer_10.10-ss.xml
>>>>>> 
>>>>>> Seems a bit over kill.
>>>>>> 
>>>>>> I was thinking more along the lines of this;
>>>>>> 
>>>>>> qemu-img snapshot -c $date $filename
>>>>>> 
>>>>>> qemu-img convert -f qcow2 -O qcow2 -s $date $filename
>>>>>> $filename-$date
>>>>>> 
>>>>>> Or something like this.Anyways, hoping to see how you all are 
>>>>>> doing
>>>>>> this for best practice sort of thing.
>>>>> 
>>>>> Hi,
>>>>> 
>>>>> I just use LVM snapshots; it's the fastest, most reliable way I
>>>>> could
>>>>> come with.
>>>> 
>>>> Hi,
>>>> 
>>>> I don't have LVMs.
>>>> 
>>>> But if I did, would it be possible to only snapshot a directory or
>>>> will it snapshot the entire file system?
>>> 
>>> Assuming you use LVM on the host to provide the virtual machine with 
>>> a
>>> (virtual) HDD, then snapshotting that will obviously be (virtual)
>>> disk-wise.
>> 
>> I used a simple non LVM partitioning scheme.
>> 
>> Can I do directory based snapshots in LVM or is it the entire FS?
>> 
>> I can re implement or redo my host to use LVM.
>> 
>> - aurf
>> _______________________________________________
>> CentOS-virt mailing list
>> CentOS-virt at centos.org
>> http://lists.centos.org/mailman/listinfo/centos-virt
> 
> Aurf,
> 
> LVM is filesystem level, not directory level. What I'd recommend is to 
> reinstall and use LVM, make a couple of volumes for / and swap and leave 
> the rest for virtual machines.

The real problem with this is that snapshots are still on the local box and I don't have a SAN.

With KVM based qcow snaps, I can do snaps over NFS.

- aurf


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