[Gluster-users] Snapshot with 4.1.1

Discussion:

Stefan Kania

2018-07-10 12:11:51 UTC

Hello,

I just installed Gluster Version 4.1.1 from, the gluster.org repository.
I tested the snapshot function and now I'm having the following problem:

When I do a "gluster volume info" BEFOR the snapshot I got:
----------

***@sambabuch-c2:~# gluster snapshot create snap1 gv1

***@sambabuch-c2:~# gluster v info

Volume Name: gv1
Type: Replicate
Volume ID: 43dcb41c-4893-4bbe-98fd-01f47810ee89
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1: knoten-1:/gluster/brick
Brick2: knoten-2:/gluster/brick
Options Reconfigured:
performance.client-io-threads: off
nfs.disable: on
transport.address-family: inet
----------
The path in "Brick1:" and "Brick2" ist ok.
Then I revert to the snapshot with:
---------

***@sambabuch-c1:~# gluster volume stop gv1

***@sambabuch-c1:~# gluster snapshot restore snap1_GMT-2018.07.10-11.36.32

***@sambabuch-c1:~# gluster v info

Volume Name: gv1
Type: Replicate
Volume ID: 43dcb41c-4893-4bbe-98fd-01f47810ee89
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1:
knoten-1:/run/gluster/snaps/ff8f9838466a4566a18fb74be82ed56d/brick1/brick
Brick2:
knoten-2:/run/gluster/snaps/ff8f9838466a4566a18fb74be82ed56d/brick2/brick
Options Reconfigured:
performance.client-io-threads: off
nfs.disable: on
transport.address-family: inet
features.quota: off
features.inode-quota: off
features.quota-deem-statfs: off
---------
As you can see, the path for "Brick1: " and "Brick2: " has changed to
the path where the snapshot is located. How do I get the original path
back?
I have never seen this wit a Gluster-Version 3.x before.

I use Debian 9. I created an LVM2 to take snapshots. The snapshots are
working, as long as I only mount the snapshot and copy some files out of
the snapshot to the volume, everything is fine. Only if I revert a
snapshot I have the problem. Is there anything new I did not do? Or how
can I got my original path back?

Thank's

Stefan

Stefan Kania

2018-07-12 08:17:19 UTC

Permalink

No one uses gluster 4.1.1 with snapshots?

Post by Stefan Kania
Hello,
I just installed Gluster Version 4.1.1 from, the gluster.org repository.
----------
Volume Name: gv1
Type: Replicate
Volume ID: 43dcb41c-4893-4bbe-98fd-01f47810ee89
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Brick1: knoten-1:/gluster/brick
Brick2: knoten-2:/gluster/brick
performance.client-io-threads: off
nfs.disable: on
transport.address-family: inet
----------
The path in "Brick1:" and "Brick2" ist ok.
---------
Volume Name: gv1
Type: Replicate
Volume ID: 43dcb41c-4893-4bbe-98fd-01f47810ee89
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
knoten-1:/run/gluster/snaps/ff8f9838466a4566a18fb74be82ed56d/brick1/brick
knoten-2:/run/gluster/snaps/ff8f9838466a4566a18fb74be82ed56d/brick2/brick
performance.client-io-threads: off
nfs.disable: on
transport.address-family: inet
features.quota: off
features.inode-quota: off
features.quota-deem-statfs: off
---------
As you can see, the path for "Brick1: " and "Brick2: " has changed to
the path where the snapshot is located. How do I get the original path
back?
I have never seen this wit a Gluster-Version 3.x before.
I use Debian 9. I created an LVM2 to take snapshots. The snapshots are
working, as long as I only mount the snapshot and copy some files out of
the snapshot to the volume, everything is fine. Only if I revert a
snapshot I have the problem. Is there anything new I did not do? Or how
can I got my original path back?
Thank's
Stefan
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Mohammed Rafi K C

2018-07-12 10:58:07 UTC

Permalink

Hi Stefan,

This is not a Gluster4 series, it is a design choice. This is the same
behavior in 3.x series also. When you restore a volume, we cannot use
the old path. Because we are not sure about the path at time when we
restore the volume. I will explain with an example.

Let's say you have 1*3 volume, and you took snapshot say snap1. Later
you decide to remove a brick and make the volume as 1*2. It is very much
possible that the removed brick will be deleted and/or mount point might
have reused for some other purpose. So when we restore the snap1, it
will have volume configuration as 1*3. If we use the same path, then the
third path is not in our gluster space.

To avoid this scenario, when a snapshot restore, we use the same
snapshot bricks. Ie volume bricks will make to point to snapshot brick.

Regards

Rafi KC

Post by Stefan Kania
No one uses gluster 4.1.1 with snapshots?

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Stefan Kania

2018-07-12 19:27:26 UTC

Permalink

Hi Rafi,

thank you for the explanation. I never thought about such a scenario.
But you are right :-). I only wonder, that I have never notice this
before. But better late then never.

Stefan

Post by Mohammed Rafi K C
Hi Stefan,
This is not a Gluster4 series, it is a design choice. This is the same
behavior in 3.x series also. When you restore a volume, we cannot use
the old path. Because we are not sure about the path at time when we
restore the volume. I will explain with an example.
Let's say you have 1*3 volume, and you took snapshot say snap1. Later
you decide to remove a brick and make the volume as 1*2. It is very much
possible that the removed brick will be deleted and/or mount point might
have reused for some other purpose. So when we restore the snap1, it
will have volume configuration as 1*3. If we use the same path, then the
third path is not in our gluster space.
To avoid this scenario, when a snapshot restore, we use the same
snapshot bricks. Ie volume bricks will make to point to snapshot brick.
Regards
Rafi KC

Post by Stefan Kania
No one uses gluster 4.1.1 with snapshots?