Gluster users - Apr 2020 - Replica 2 to replica 3

Hello,

I have a live gluster setup like this:

    Volume Name: MRIData
    Type: Distributed-Replicate
    Volume ID: e051ac20-ead1-4648-9ac6-a29b531515ca
    Status: Started
    Snapshot Count: 0
    Number of Bricks: 6 x 2 = 12
    Transport-type: tcp
    Bricks:
    Brick1: hydra1:/gluster1/data
    Brick2: hydra1:/gluster2/data
    Brick3: hydra1:/gluster3/data
    Brick4: hydra2:/gluster1/data
    Brick5: hydra2:/gluster2/data
    Brick6: hydra2:/gluster3/data
    Brick7: hydra3:/gluster1/data
    Brick8: hydra3:/gluster2/data
    Brick9: hydra3:/gluster3/data
    Brick10: hydra4:/gluster1/data
    Brick11: hydra4:/gluster2/data
    Brick12: hydra4:/gluster3/data
    Options Reconfigured:
    transport.address-family: inet
    nfs.disable: on
    nfs.exports-auth-enable: on
    features.cache-invalidation: off

This was set up as a replica 2 and I would like now to turn into a 
replica 3. I believe it's possible without loss of data (combination of 
"replace-brick" and other commands), but cannot find any docs
describing
the process.

Am I right that it is possible ? Where can I find documentation ?

Thanks,

-- 
As a result of Coronavirus-related precautions, NYU and the Center for 
Brain Imaging operations will be managed remotely until further notice.
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remotely during our normal business hours of 9am-5pm, Monday through 
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For MRI scanner-related emergency, please contact: Keith Sanzenbach at 
keith.sanzenbach at nyu.edu and/or Pablo Velasco at pablo.velasco at nyu.edu
For computer/hardware/software emergency, please contact: Valerio Luccio 
at valerio.luccio at nyu.edu
For TMS/EEG-related emergency, please contact: Chrysa Papadaniil at 
chrysa at nyu.edu
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Mangan at jennifer.mangan at nyu.edu

Valerio Luccio 		(212) 998-8736
Center for Brain Imaging 		4 Washington Place, Room 158
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On April 3, 2020 10:12:19 PM GMT+03:00, Valerio Luccio <valerio.luccio at
nyu.edu> wrote:
>Hello,
>
>I have a live gluster setup like this:
>
>    Volume Name: MRIData
>    Type: Distributed-Replicate
>    Volume ID: e051ac20-ead1-4648-9ac6-a29b531515ca
>    Status: Started
>    Snapshot Count: 0
>    Number of Bricks: 6 x 2 = 12
>    Transport-type: tcp
>    Bricks:
>    Brick1: hydra1:/gluster1/data
>    Brick2: hydra1:/gluster2/data
>    Brick3: hydra1:/gluster3/data
>    Brick4: hydra2:/gluster1/data
>    Brick5: hydra2:/gluster2/data
>    Brick6: hydra2:/gluster3/data
>    Brick7: hydra3:/gluster1/data
>    Brick8: hydra3:/gluster2/data
>    Brick9: hydra3:/gluster3/data
>    Brick10: hydra4:/gluster1/data
>    Brick11: hydra4:/gluster2/data
>    Brick12: hydra4:/gluster3/data
>    Options Reconfigured:
>    transport.address-family: inet
>    nfs.disable: on
>    nfs.exports-auth-enable: on
>    features.cache-invalidation: off
>
>This was set up as a replica 2 and I would like now to turn into a 
>replica 3. I believe it's possible without loss of data (combination of
>
>"replace-brick" and other commands), but cannot find any docs
>describing 
>the process.
>
>Am I right that it is possible ? Where can I find documentation ?
>
>Thanks,
Yeah it's possible.
You can add an arbiter or a full  replica depending on your needs.

Actually the info described here  is quite usefull:
https://access.redhat.com/documentation/en-us/red_hat_gluster_storage/3.4/html/administration_guide/creating_arbitrated_replicated_volumes

Instead of arbiter, you can place a full brick, but you need to follow the
warning:
1. Remove geo replication
2. Disable self healing

Of course,it  is better to create a test volume  (even with a few GB for the
bricks) and test on it before executing on production.


Best Regards,
Strahil Nikolov