On 05/01/2017 02:47 PM, Pranith Kumar Karampuri wrote:
On Tue, May 2, 2017 at 12:14 AM, Shyam <srangana@xxxxxxxxxx <mailto:srangana@xxxxxxxxxx>> wrote: On 05/01/2017 02:42 PM, Pranith Kumar Karampuri wrote: On Tue, May 2, 2017 at 12:07 AM, Shyam <srangana@xxxxxxxxxx <mailto:srangana@xxxxxxxxxx> <mailto:srangana@xxxxxxxxxx <mailto:srangana@xxxxxxxxxx>>> wrote: On 05/01/2017 02:23 PM, Pranith Kumar Karampuri wrote: On Mon, May 1, 2017 at 11:43 PM, Shyam <srangana@xxxxxxxxxx <mailto:srangana@xxxxxxxxxx> <mailto:srangana@xxxxxxxxxx <mailto:srangana@xxxxxxxxxx>> <mailto:srangana@xxxxxxxxxx <mailto:srangana@xxxxxxxxxx> <mailto:srangana@xxxxxxxxxx <mailto:srangana@xxxxxxxxxx>>>> 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.
Yes, while discussing DHT2, Quota-2 [1] was discussed and project quotas and how to leverage the design in gluster was also discussed. IMO (again), this would be the right way forward for quota (orthogonal to this discussion, but still).
[1] Quota-2 discussion: http://lists.gluster.org/pipermail/gluster-devel/2015-December/047443.html
It all seems to point that we basically need to increase granularity of brick and solve problems that come up as we go along.
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