[Gluster-users] Add single server

[Pranith Kumar Karampuri]

On Tue, May 2, 2017 at 12:14 AM, Shyam <srangana at redhat.com> wrote:

> On 05/01/2017 02:42 PM, Pranith Kumar Karampuri wrote:
>
>>
>>
>> On Tue, May 2, 2017 at 12:07 AM, Shyam <srangana at redhat.com
>> <mailto:srangana at redhat.com>> wrote:
>>
>>     On 05/01/2017 02:23 PM, Pranith Kumar Karampuri wrote:
>>
>>
>>
>>         On Mon, May 1, 2017 at 11:43 PM, Shyam <srangana at redhat.com
>>         <mailto:srangana at redhat.com>
>>         <mailto:srangana at redhat.com <mailto:srangana at redhat.com>>> wrote:
>>
>>             On 05/01/2017 02:00 PM, Pranith Kumar Karampuri wrote:
>>
>>                     Splitting the bricks need not be a post factum
>>         decision, we can
>>                     start with larger brick counts, on a given node/disk
>>         count, and
>>                     hence spread these bricks to newer nodes/bricks as
>>         they are
>>                 added.
>>
>>
>>                 Let's say we have 1 disk, we format it with say XFS and
>> that
>>                 becomes a
>>                 brick at the moment. Just curious, what will be the
>>         relationship
>>                 between
>>                 brick to disk in this case(If we leave out LVM for this
>>         example)?
>>
>>
>>             I would assume the relation is brick to provided FS
>>         directory (not
>>             brick to disk, we do not control that at the moment, other
>> than
>>             providing best practices around the same).
>>
>>
>>         Hmmm... as per my understanding, if we do this then 'df' I guess
>>         will
>>         report wrong values? available-size/free-size etc will be
>>         counted more
>>         than once?
>>
>>
>>     This is true even today, if anyone uses 2 bricks from the same mount.
>>
>>
>> That is the reason why documentation is the way it is as far as I can
>> remember.
>>
>>
>>
>>     I forgot a converse though, we could take a disk and partition it
>>     (LVM thinp volumes) and use each of those partitions as bricks,
>>     avoiding the problem of df double counting. Further thinp will help
>>     us expand available space to other bricks on the same disk, as we
>>     destroy older bricks or create new ones to accommodate the moving
>>     pieces (needs more careful thought though, but for sure is a
>>     nightmare without thinp).
>>
>>     I am not so much a fan of large number of thinp partitions, so as
>>     long as that is reasonably in control, we can possibly still use it.
>>     The big advantage though is, we nuke a thinp volume when the brick
>>     that uses that partition, moves out of that disk, and we get the
>>     space back, rather than having or to something akin to rm -rf on the
>>     backend to reclaim space.
>>
>>
>> Other way to achieve the same is to leverage the quota functionality of
>> counting how much size is used under a directory.
>>
>
> Yes, I think this is the direction to solve the 2 bricks on a single FS as
> well. Also, IMO, the weight of accounting at each directory level that
> quota brings in seems/is heavyweight to solve just *this* problem.


I saw some github issues where Sanoj is exploring XFS-quota integration.
Project Quota ideas which are a bit less heavy would be nice too. Actually
all these issues are very much interlinked.

It all seems to point that we basically need to increase granularity of
brick and solve problems that come up as we go along.


>
>
>
>>
>>
>>
>>
>>
>>
>>             Today, gluster takes in a directory on host as a brick, and
>>         assuming
>>             we retain that, we would need to split this into multiple
>>         sub-dirs
>>             and use each sub-dir as a brick internally.
>>
>>             All these sub-dirs thus created are part of the same volume
>>         (due to
>>             our current snapshot mapping requirements).
>>
>>
>>
>>
>>         --
>>         Pranith
>>
>>
>>
>>
>> --
>> Pranith
>>
>


-- 
Pranith
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