[Gluster-users] Removing subvolume from dist/rep volume

[Nithya Balachandran]

On Thu, 27 Jun 2019 at 12:17, Nithya Balachandran <nbalacha at redhat.com>
wrote:

> Hi,
>
>
> On Tue, 25 Jun 2019 at 15:26, Dave Sherohman <dave at sherohman.org> wrote:
>
>> I have a 9-brick, replica 2+A cluster and plan to (permanently) remove
>> one of the three subvolumes.  I think I've worked out how to do it, but
>> want to verify first that I've got it right, since downtime or data loss
>> would be Bad Things.
>>
>> The current configuration has six data bricks across six hosts (B
>> through G), and all three arbiter bricks on the same host (A), such as
>> one might create with
>>
>> # gluster volume create myvol replica 3 arbiter 1 B:/data C:/data A:/arb1
>> D:/data E:/data A:/arb2 F:/data G:/data A:/arb3
>>
>>
>> My objective is to remove nodes B and C entirely.
>>
>> First up is to pull their bricks from the volume:
>>
>> # gluster volume remove-brick myvol B:/data C:/data A:/arb1 start
>> (wait for data to be migrated)
>> # gluster volume remove-brick myvol B:/data C:/data A:/arb1 commit
>>
>>
> There are some edge cases that may prevent a file from being migrated
> during a remove-brick. Please do the following after this:
>
>    1. Check the remove-brick status for any failures.  If there are any,
>    check the rebalance log file for errors.
>    2. Even if there are no failures, check the removed bricks to see if
>    any files have not been migrated. If there are any, please check that they
>    are valid files on the brick and that they match on both bricks (files are
>    not in split brain) and copy them to the volume from the brick to the mount
>    point.
>
> You can run the following at the root of the brick to find any files that
have not been migrated:

find . -not \( -path ./.glusterfs -prune \) -type f -not -perm 01000


> The rest of the steps look good.
>
> Regards,
> Nithya
>
>> And then remove the nodes with:
>>
>> # gluster peer detach B
>> # gluster peer detach C
>>
>>
>> Is this correct, or did I forget any steps and/or mangle the syntax on
>> any commands?
>>
>> Also, for the remove-brick command, is there any way to throttle the
>> amount of bandwidth which will be used for the data migration?
>> Unfortunately, I was not able to provision a dedicated VLAN for the
>> gluster servers to communicate among themselves, so I don't want it
>> hogging all available capacity if that can be avoided.
>>
>>
>> If it makes a difference, my gluster version is 3.12.15-1, running on
>> Debian and installed from the debs at
>>
>> deb
>> https://download.gluster.org/pub/gluster/glusterfs/3.12/LATEST/Debian/9/amd64/apt
>> stretch main
>>
>> --
>> Dave Sherohman
>> _______________________________________________
>> Gluster-users mailing list
>> Gluster-users at gluster.org
>> https://lists.gluster.org/mailman/listinfo/gluster-users
>>
>
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