Re: gluster volume snap shot - basic questions

[Merlin Morgenstern <merlin.morgenstern@xxxxxxxxx>]

Thank you Rjesh for your help. I have a thinly provisioned LVM now running and can create snapshots on a real device, surviving boot.

There are 2 other questions rising up now.

1. I have a LV with 20G, data is 7G. How is it possible, that I could make 3 snapshots, each 7G?

/dev/mapper/gluster-thinv1                               20G  7.0G   12G  38% /bricks/brick1

/dev/mapper/gluster-7cb4b2c8f8a64ceaba62bc4ca6cd76b2_0   20G  7.0G   12G  38% /run/gluster/snaps/7cb4b2c8f8a64ceaba62bc4ca6cd76b2/brick1

/dev/mapper/gluster-506cb09085b2428e9daca8ac0857c2c9_0   20G  7.0G   12G  38% /run/gluster/snaps/506cb09085b2428e9daca8ac0857c2c9/brick1

/dev/mapper/gluster-fbee900c1cc7407f9527f98206e6566d_0   20G  7.0G   12G  38% /run/gluster/snaps/fbee900c1cc7407f9527f98206e6566d/brick1

/dev/mapper/gluster-d0c254908dca451d8f566be77437c538_0   20G  7.0G   12G  38% /run/gluster/snaps/d0c254908dca451d8f566be77437c538/brick1

2. The name of the snapshot folder is the UUID, My plan is to do a "tar cf" on the snapshot and even incremental tars. Therefore I would need the name of the folder. How could I pass that name to my bash script in order to make a backup of the last snap?

3. A tar process will take hours on the million files I have. I understand this is a snapshot, is there a way to backup a "single" snapshot file instead?

Thank you in advance for sheding some light on this topic

2015-09-02 7:59 GMT+02:00 Rajesh Joseph <rjoseph@xxxxxxxxxx>:

----- Original Message -----
> From: "Merlin Morgenstern" <merlin.morgenstern@xxxxxxxxx>
> To: "gluster-users" <gluster-users@xxxxxxxxxxx>
> Sent: Tuesday, September 1, 2015 3:15:43 PM
> Subject: gluster volume snap shot - basic questions
>
> Hi everybody,
>
> I am looking into the snap shot tool, following this tutorial:
> http://blog.gluster.org/2014/10/gluster-volume-snapshot-howto/
>
> While having successfully created the LVM, gluster volume and one snapshot,
> there are some questions arrising where I was hoping to find some guidence
> here:
>
> 1. From a working setup as in the example I rebooted and everything was gone.
> How can I make this setup persistent, so the gluster share is up and running
> after boot.
>

What do you mean by "everything was gone"? Are you using loop back device as disks?
If yes then this is expected. Loop back device mapping is gone after machine restart.
You should test with real disk or lvm partition.

> 2. I understand that the snaps are under /var/run/gluster/snaps/ and I found
> them there. Is it save to simply copy them to another server for backup? My
> goal is to create a backup each day and transfer the snaps to an FTP-Server
> in order to be able to recover from a broken machine.
>

Yes, snap of individual bricks are mounted at /var/run/gluster/snaps/. I am assuming
that you mean copy of data hosted on the snap brick when you say copy the snap.
Are you planning to use some backup software or to run rsync on each brick?

> 3. Do I really need LVM to use this feature? Currently my setup works on the
> native system. As I understand the tuturial I would need to move that to a
> LV, right?
>

Yes, you need LVM and to be precise thinly provisioned LVM for snapshot to work.

> Thank you in advance on any help!
>
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