[Gluster-users] using a preferred node ?

Ravishankar N ravishankar at redhat.com
Mon Jun 8 04:37:07 UTC 2015



On 06/06/2015 12:49 AM, Mathieu Chateau wrote:
> Hello,
>
> sorry to bother again but I am still facing this issue.
>
> client still looks on the "other side" and not using the node declared 
> in fstab:
> prd-sta-sto01:/gluster-preprod /mnt/gluster-preprod glusterfs 
> defaults,_netdev,backupvolfile-server=prd-sta-sto02 0 0
>
> I expect client to use sto01 and not sto02 as it's available.

Hi Mathieu,
When you do lookups (`ls` etc), they are sent to both bricks of the 
replica. If you write to a file, the write is also sent to both bricks. 
This is how it works. Only reads are served from the local brick.
-Ravi

>
> If I add a static route to break connectivity to sto02 and do a "df", 
> I have around 30s before it works.
> Then it works ok.
>
> Questions:
>
>   * How to force node to stick as possible with one specific (local)
>     node ?
>   * How to know where a client is currently connected?
>
> Thanks for your help :)
>
>
> Cordialement,
> Mathieu CHATEAU
> http://www.lotp.fr
>
> 2015-05-11 7:26 GMT+02:00 Mathieu Chateau <mathieu.chateau at lotp.fr 
> <mailto:mathieu.chateau at lotp.fr>>:
>
>     Hello,
>
>     thanks for helping :)
>
>     If gluster server is rebooted, any way to make client failback on
>     node after reboot ?
>
>     How to know which node is using a client ? I see TCP connection to
>     both node
>
>     Regards,
>
>     Cordialement,
>     Mathieu CHATEAU
>     http://www.lotp.fr
>
>     2015-05-11 7:13 GMT+02:00 Ravishankar N <ravishankar at redhat.com
>     <mailto:ravishankar at redhat.com>>:
>
>
>
>         On 05/10/2015 08:29 PM, Mathieu Chateau wrote:
>>         Hello,
>>
>>         Short way: Is there any way to define a preferred Gluster
>>         server ?
>>
>>         Long way:
>>         I have the following setup (version 3.6.3) :
>>
>>         Gluster A  <==> VPN <==> Gluster B
>>
>>         Volume is replicated between A and B.
>>
>>         They are in same datacenter, using a 1Gb/s connection, low
>>         latency (0.5ms)
>>
>>         I have gluster clients in lan A & B.
>>
>>         When doing a "ls" on big folder (~60k files), both gluster
>>         node are used, and so it need 9mn instead on 1mn if only the
>>         local gluster is reachable.
>>
>
>         Lookups (and writes of course) from clients are sent to both 
>         bricks because AFR uses the result of the lookup to select
>         which brick to read from if there is a pending heal etc.
>         If the file is clean on both A and B, then reads are always
>         served from the local brick. i.e. reads on clients mounted on
>         A will be served from the brick in A (and likewise for B).
>
>         Hope that helps,
>         Ravi
>
>
>>         It's HA setup, application is present on both side. I would
>>         like a master/master setup, but using only local node as
>>         possible.
>>
>>
>>         Regards,
>>         Mathieu CHATEAU
>>         http://www.lotp.fr
>>
>>
>>         _______________________________________________
>>         Gluster-users mailing list
>>         Gluster-users at gluster.org  <mailto:Gluster-users at gluster.org>
>>         http://www.gluster.org/mailman/listinfo/gluster-users
>
>
>

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