Gluster users - Nov 2019 - how to downgrade GlusterFS from version 7 to 3.13?

Hello,

Is there any way to downgrade a GlusterFS cluster?  Given the
performance issues that I have seen with GlusterFS 6 and 7 (reported
elsewhere on this mailing-list), I am now considering downgrading back
to GlusterFS 3.13.

I have set up a test cluster, copied some files on it, and tried to
downgrade the naive way (uninstall GlusterFS 7, install GlusterFS
3.13, do not touch bricks or other config).  This didn't work:
`glusterd` v3.13 complains that the o-version 70000 cannot be
restored.

So I tried again, this time trying to lower op-version before
downgrading the system packages, but `gluster set all op-version`
won't let me:

```
$ sudo gluster volume set all cluster.op-version 31000
volume set: failed: Required op-version (31000) should not be equal or
lower than current cluster op-version (70000).
```

What can I try next?

Thanks,
Riccardo

On Wed, Nov 6, 2019 at 2:05 PM Riccardo Murri <riccardo.murri at
gmail.com>
wrote:
> Hello,
>
> Is there any way to downgrade a GlusterFS cluster?  Given the
> performance issues that I have seen with GlusterFS 6 and 7 (reported
> elsewhere on this mailing-list), I am now considering downgrading back
> to GlusterFS 3.13.
>
> I have set up a test cluster, copied some files on it, and tried to
> downgrade the naive way (uninstall GlusterFS 7, install GlusterFS
> 3.13, do not touch bricks or other config).  This didn't work:
> `glusterd` v3.13 complains that the o-version 70000 cannot be
> restored.
>
> So I tried again, this time trying to lower op-version before
> downgrading the system packages, but `gluster set all op-version`
> won't let me:
>
> ```
> $ sudo gluster volume set all cluster.op-version 31000
> volume set: failed: Required op-version (31000) should not be equal or
> lower than current cluster op-version (70000).
> ```
>
> What can I try next?
>
>
We don't advise downgrade, and don't test downgrade as part of any
automated tests right now.

Disclaimer: Below is not tested

Considering you have some genuine issue, and there are no new options added
with new version, try editing '/var/lib/glusterd/glusterd.info' file,
and
change the op-version manually in all machines, and restart glusterd.

-Amar

> Thanks,
> Riccardo
> ________
>
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>
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Just delete all gluster stuff, including volumes, configs and .gluster
folder on bricks
Point new volumes 3.13 to same brick locations and run stat on each file
https://lists.gluster.org/pipermail/gluster-users/2018-January/033352.html

v

On Wed, Nov 6, 2019 at 3:35 AM Riccardo Murri <riccardo.murri at
gmail.com>
wrote:
> Hello,
>
> Is there any way to downgrade a GlusterFS cluster?  Given the
> performance issues that I have seen with GlusterFS 6 and 7 (reported
> elsewhere on this mailing-list), I am now considering downgrading back
> to GlusterFS 3.13.
>
> I have set up a test cluster, copied some files on it, and tried to
> downgrade the naive way (uninstall GlusterFS 7, install GlusterFS
> 3.13, do not touch bricks or other config).  This didn't work:
> `glusterd` v3.13 complains that the o-version 70000 cannot be
> restored.
>
> So I tried again, this time trying to lower op-version before
> downgrading the system packages, but `gluster set all op-version`
> won't let me:
>
> ```
> $ sudo gluster volume set all cluster.op-version 31000
> volume set: failed: Required op-version (31000) should not be equal or
> lower than current cluster op-version (70000).
> ```
>
> What can I try next?
>
> Thanks,
> Riccardo
> ________
>
> Community Meeting Calendar:
>
> APAC Schedule -
> Every 2nd and 4th Tuesday at 11:30 AM IST
> Bridge: https://bluejeans.com/118564314
>
> NA/EMEA Schedule -
> Every 1st and 3rd Tuesday at 01:00 PM EDT
> Bridge: https://bluejeans.com/118564314
>
> Gluster-users mailing list
> Gluster-users at gluster.org
> https://lists.gluster.org/mailman/listinfo/gluster-users
>
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