[ovirt-users] How to create a new Gluster volume

[knarra]

On 07/07/2017 02:03 PM, Gianluca Cecchi wrote:
> On Fri, Jul 7, 2017 at 10:15 AM, knarra <knarra at redhat.com 
> <mailto:knarra at redhat.com>> wrote:
>
>
>>
>>
>>     It seems I have to de-select the checkbox "Show available bricks
>>     from host" and so I can manually the the directory of the bricks
>     I see that bricks are mounted in /gluster/brick3 and that is the
>     reason it does not show anything in "Brick Directory" drop down
>     filed. If bricks are mounted under /gluster_bricks then it would
>     have detected automatically. There is an RFE which is raised to
>     detect bricks which are created manually.
>
>
> I deployed this HCI system with gdeploy at oVirt 4.05 time, so I think 
> I used the "default" path that was proposed inside the 
> ovirt-gluster.conf file to feed gdeploy with...
> I think it was based on this from Jason:
> https://www.ovirt.org/blog/2016/08/up-and-running-with-ovirt-4-0-and-gluster-storage/
> and this conf file
> https://gist.githubusercontent.com/jasonbrooks/a5484769eea5a8cf2fa9d32329d5ebe5/raw/ovirt-gluster.conf
>
> Good that there is an RFE. Thanks
>
>
>>
>>     BTW: I see that after creating a volume optimized for oVirt in
>>     web admin gui of 4.1.2 I get slight option for it in respect for
>>     a pre-existing volume created in 4.0.5 during initial setup with
>>     gdeploy.
>>
>>     NOTE: during 4.0.5 setup I had gluster 3.7 installed, while now I
>>     have gluster 3.10 (manually updated from CentOS storage SIG)
>>
>>     Making a "gluster volume info" and then a diff of the output for
>>     the 2 volumes I have:
>>
>>     new volume ==   <
>>     old volume  ==    >
>>
>>     < cluster.shd-max-threads: 8
>>     ---
>>     > cluster.shd-max-threads: 6
>>     13a13,14
>>     > features.shard-block-size: 512MB
>>     16c17
>>     < network.remote-dio: enable
>>     ---
>>     > network.remote-dio: off
>>     23a25
>>     > performance.readdir-ahead: on
>>     25c27
>>     < server.allow-insecure: on
>>     ---
>>     > performance.strict-o-direct: on
>>
>>     Do I have to change anything for the newly created one?
>     No, you do not need to change anything for the new volume. But if
>     you plan to enable o-direct on the volume then you will have to
>     disable/turn off remote-dio.
>
>
> OK.
> Again, in ovirt-gluster.conf file I see there was this kind of setting 
> for the Gluster volumes when running gdeploy for them:
> key=group,storage.owner-uid,storage.owner-gid,features.shard,features.shard-block-size,performance.low-prio-threads,cluster.data-self-heal-algorithm,cluster.locking-scheme,cluster.shd-wait-qlength,cluster.shd-max-threads,network.ping-timeout,user.cifs,performance.strict-o-direct,network.remote-dio,cluster.granular-entry-heal
> value=virt,36,36,on,512MB,32,full,granular,10000,8,30,off,on,off,on
> brick_dirs=/gluster/brick1/engine
> I'm going to crosscheck now what are the suggested values for oVirt 
> 4.1 and Gluster 3.10 combined...
Now virt group sets the shard block size and it is the default which is 
4MB and is the suggested value. With 4MB shards we see that healing is 
much faster with granular entry heal being enabled on the volume.

I am not sure why the conf file again sets the shard size. May be this 
can be removed from the file.

Other than this everything looks good for me.
>
> I was in particular worried by the difference 
> of features.shard-block-size but after reading this
>
> http://blog.gluster.org/2015/12/introducing-shard-translator/
>
> I'm not sure if 512Mb is the best in case of VMs storage.... I'm going 
> to dig more eventually
>
> Thanks,
> Gianluca


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