[Gluster-users] Backups

Thu Mar 23 22:46:12 UTC 2017

The problem is not how to backup, but how to restore.
How do you restore a whole cluster made of thousands of VMs ?

If you move all VMs to a shared storage like gluster, you should
consider how to recover everything from the gluster failure.
If you had a bounch of VMs on each server with local disks, you had to
recover only VMs affected by a single server failure,
but moving everything to a shared storage means to be prepared for a
disaster, where you *must* restore everything or hundreds of TB.

2017-03-23 23:07 GMT+01:00 Gambit15 <dougti+gluster at gmail.com>:
> Don't snapshot the entire gluster volume, keep a rolling routine for
> snapshotting the individual VMs & rsync those.
> As already mentioned, you need to "itemize" the backups - trying to manage
> backups for the whole volume as a single unit is just crazy!
>
> Also, for long term backups, maintaining just the core data of each VM is
> far more manageable.
>
> I settled on oVirt for our platform, and do the following...
>
> A cronjob regularly snapshots & clones each VM, whose image is then rsynced
> to our backup storage;
> The backup server snapshots the VM's image backup volume to maintain
> history/versioning;
> These full images are only maintained for 30 days, for DR purposes;
> A separate routine rsyncs the VM's core data to its own data backup volume,
> which is snapshotted & maintained for 10 years;
>
> This could be made more efficient by using guestfish to extract the core
> data from backup image, instead of basically rsyncing the data across the
> network twice.
>
> That active storage layer uses Gluster on top of XFS & LVM. The backup
> storage layer uses a mirrored storage unit running ZFS on FreeNAS.
> This of course doesn't allow for HA in the case of the entire cloud failing.
> For that we'd use geo-rep & a big fat pipe.
>
> D
>
> On 23 March 2017 at 16:29, Gandalf Corvotempesta
> <gandalf.corvotempesta at gmail.com> wrote:
>>
>> Yes but the biggest issue is how to recover
>> You'll need to recover the whole storage not a single snapshot and this
>> can last for days
>>
>> Il 23 mar 2017 9:24 PM, "Alvin Starr" <alvin at netvel.net> ha scritto:
>>>
>>> For volume backups you need something like snapshots.
>>>
>>> If you take a snapshot A of a live volume L that snapshot stays at that
>>> moment in time and you can rsync that to another system or use something
>>> like deltacp.pl to copy it.
>>>
>>> The usual process is to delete the snapshot once its copied and than
>>> repeat the process again when the next backup is required.
>>>
>>> That process does require rsync/deltacp to read the complete volume on
>>> both systems which can take a long time.
>>>
>>> I was kicking around the idea to try and handle snapshot deltas better.
>>>
>>> The idea is that you could take your initial snapshot A then sync that
>>> snapshot to your backup system.
>>>
>>> At a later point you could take another snapshot B.
>>>
>>> Because snapshots contain the copies of the original data at the time of
>>> the snapshot and unmodified data points to the Live volume it is possible to
>>> tell what blocks of data have changed since the snapshot was taken.
>>>
>>> Now that you have a second snapshot you can in essence perform a diff on
>>> the A and B snapshots to get only the blocks that changed up to the time
>>> that B was taken.
>>>
>>> These blocks could be copied to the backup image and you should have a
>>> clone of the B snapshot.
>>>
>>> You would not have to read the whole volume image but just the changed
>>> blocks dramatically improving the speed of the backup.
>>>
>>> At this point you can delete the A snapshot and promote the B snapshot to
>>> be the A snapshot for the next backup round.
>>>
>>>
>>> On 03/23/2017 03:53 PM, Gandalf Corvotempesta wrote:
>>>
>>> Are backup consistent?
>>> What happens if the header on shard0 is synced referring to some data on
>>> shard450 and when rsync parse shard450 this data is changed by subsequent
>>> writes?
>>>
>>> Header would be backupped  of sync respect the rest of the image
>>>
>>> Il 23 mar 2017 8:48 PM, "Joe Julian" <joe at julianfamily.org> ha scritto:
>>>>
>>>> The rsync protocol only passes blocks that have actually changed. Raw
>>>> changes fewer bits. You're right, though, that it still has to check the
>>>> entire file for those changes.
>>>>
>>>>
>>>> On 03/23/17 12:47, Gandalf Corvotempesta wrote:
>>>>
>>>> Raw or qcow doesn't change anything about the backup.
>>>> Georep always have to sync the whole file
>>>>
>>>> Additionally, raw images has much less features than qcow
>>>>
>>>> Il 23 mar 2017 8:40 PM, "Joe Julian" <joe at julianfamily.org> ha scritto:
>>>>>
>>>>> I always use raw images. And yes, sharding would also be good.
>>>>>
>>>>>
>>>>> On 03/23/17 12:36, Gandalf Corvotempesta wrote:
>>>>>
>>>>> Georep expose to another problem:
>>>>> When using gluster as storage for VM, the VM file is saved as qcow.
>>>>> Changes are inside the qcow, thus rsync has to sync the whole file every
>>>>> time
>>>>>
>>>>> A little workaround would be sharding, as rsync has to sync only the
>>>>> changed shards, but I don't think this is a good solution
>>>>>
>>>>> Il 23 mar 2017 8:33 PM, "Joe Julian" <joe at julianfamily.org> ha scritto:
>>>>>>
>>>>>> In many cases, a full backup set is just not feasible. Georep to the
>>>>>> same or different DC may be an option if the bandwidth can keep up with the
>>>>>> change set. If not, maybe breaking the data up into smaller more manageable
>>>>>> volumes where you only keep a smaller set of critical data and just back
>>>>>> that up. Perhaps an object store (swift?) might handle fault tolerance
>>>>>> distribution better for some workloads.
>>>>>>
>>>>>> There's no one right answer.
>>>>>>
>>>>>>
>>>>>> On 03/23/17 12:23, Gandalf Corvotempesta wrote:
>>>>>>
>>>>>> Backing up from inside each VM doesn't solve the problem
>>>>>> If you have to backup 500VMs you just need more than 1 day and what if
>>>>>> you have to restore the whole gluster storage?
>>>>>>
>>>>>> How many days do you need to restore 1PB?
>>>>>>
>>>>>> Probably the only solution should be a georep in the same
>>>>>> datacenter/rack with a similiar cluster,
>>>>>> ready to became the master storage.
>>>>>> In this case you don't need to restore anything as data are already
>>>>>> there,
>>>>>> only a little bit back in time but this double the TCO
>>>>>>
>>>>>> Il 23 mar 2017 6:39 PM, "Serkan Çoban" <cobanserkan at gmail.com> ha
>>>>>> scritto:
>>>>>>>
>>>>>>> Assuming a backup window of 12 hours, you need to send data at 25GB/s
>>>>>>> to backup solution.
>>>>>>> Using 10G Ethernet on hosts you need at least 25 host to handle
>>>>>>> 25GB/s.
>>>>>>> You can create an EC gluster cluster that can handle this rates, or
>>>>>>> you just backup valuable data from inside VMs using open source
>>>>>>> backup
>>>>>>> tools like borg,attic,restic , etc...
>>>>>>>
>>>>>>> On Thu, Mar 23, 2017 at 7:48 PM, Gandalf Corvotempesta
>>>>>>> <gandalf.corvotempesta at gmail.com> wrote:
>>>>>>> > Let's assume a 1PB storage full of VMs images with each brick over
>>>>>>> > ZFS,
>>>>>>> > replica 3, sharding enabled
>>>>>>> >
>>>>>>> > How do you backup/restore that amount of data?
>>>>>>> >
>>>>>>> > Backing up daily is impossible, you'll never finish the backup that
>>>>>>> > the
>>>>>>> > following one is starting (in other words, you need more than 24
>>>>>>> > hours)
>>>>>>> >
>>>>>>> > Restoring is even worse. You need more than 24 hours with the whole
>>>>>>> > cluster
>>>>>>> > down
>>>>>>> >
>>>>>>> > You can't rely on ZFS snapshot due to sharding (the snapshot took
>>>>>>> > from one
>>>>>>> > node is useless without all other node related at the same shard)
>>>>>>> > and you
>>>>>>> > still have the same restore speed
>>>>>>> >
>>>>>>> > How do you backup this?
>>>>>>> >
>>>>>>> > Even georep isn't enough, if you have to restore the whole storage
>>>>>>> > in case
>>>>>>> > of disaster
>>>>>>> >
>>>>>>> > _______________________________________________
>>>>>>> > Gluster-users mailing list
>>>>>>> > Gluster-users at gluster.org
>>>>>>> > http://lists.gluster.org/mailman/listinfo/gluster-users
>>>>>>
>>>>>>
>>>>>>
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>>>
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>>> --
>>> Alvin Starr                   ||   voice: (905)513-7688
>>> Netvel Inc.                   ||   Cell:  (416)806-0133
>>> alvin at netvel.net              ||
>>>
>>>
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