[Gluster-users] How large the Arbiter node?

[Ben Turner]

----- Original Message -----
> From: "Martin Toth" <snowmailer at gmail.com>
> To: "Nux!" <nux at li.nux.ro>
> Cc: "gluster-users" <gluster-users at gluster.org>, "Gluster Devel" <gluster-devel at gluster.org>
> Sent: Monday, December 11, 2017 11:58:39 AM
> Subject: Re: [Gluster-users] How large the Arbiter node?
> 
> Hi,
> 
> there is good suggestion here :
> http://docs.gluster.org/en/latest/Administrator%20Guide/arbiter-volumes-and-quorum/#arbiter-bricks-sizing
> Since the arbiter brick does not store file data, its disk usage will be
> considerably less than the other bricks of the replica. The sizing of the
> brick will depend on how many files you plan to store in the volume. A good
> estimate will be 4kb times the number of files in the replica.

You can see the explanation from the DEV here:

http://lists.gluster.org/pipermail/gluster-users/2016-March/025732.html

The 4k number was derived by adding 100 xattrs to a file:

[root at ravi4 brick]# touch file

[root at ravi4 brick]# ls -l file
-rw-r--r-- 1 root root 0 Mar  8 12:54 file

[root at ravi4 brick]# du file
*0       file**
*
[root at ravi4 brick]# for i in {1..100}
 > do
 > setfattr -n user.value$i -v value$i file
 > done

[root at ravi4 brick]# ll -l file
-rw-r--r-- 1 root root 0 Mar  8 12:54 file

[root at ravi4 brick]# du -h file
*4.0K    file**

The 4k number may be a little conservative but in all of the clusters I help architect I follow that rule.

HTH!

-b


> 
> BR,
> 
> Martin
> 
> 
> 
> 
> On 11 Dec 2017, at 17:43, Nux! < nux at li.nux.ro > wrote:
> 
> Hi,
> 
> I see gluster now recommends the use of an arbiter brick in "replica 2"
> situations.
> How large should this brick be? I understand only metadata is to be stored.
> Let's say total storage usage will be 5TB of mixed size files. How large
> should such a brick be?
> 
> --
> Sent from the Delta quadrant using Borg technology!
> 
> Nux!
> www.nux.ro
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