[Gluster-users] Cheers and some thoughts

Lindsay Mathieson lindsay.mathieson at gmail.com
Wed Jan 4 22:43:34 UTC 2017

Hi all, just wanted to mention that since I had sole use of our cluster 
over the holidays and a complete set of backups :) I decided to test 
some alternate cluster software and do some stress testing.

Stress testing involved multiple soft and *hard* resets of individual 
servers and hard simultaneous resets of the entire cluster, where a hard 
reset is equivalent to a power outage.

Gluster (3.8.7) coped perfectly - no data loss, no maintenance required, 
each time it came up by itself with no hand holding and started healing 
nodes, which completed very quickly. VM's on gluster auto started with 
no problems, i/o load while healing was ok. I felt quite confident in it.

The alternate cluster fs - not so good. Many times running VM's were 
corrupted, several times I lost the entire filesystem. Also IOPS where 
atrocious (fuse based). It easy to claim HA when you exclude such things 
as power supply failures, dodgy network switches etc.

I think glusters active/active quorum based design, where is every node 
is a master is a winner, active/passive systems where you have a SPOF 
master are difficult to DR manage.

However :) Things I'd really like to see in Gluster:

- More flexible/easier management of servers and bricks (add/remove/replace)

- More flexible replication rules

One of the things I really *really* like with LizardFS is the powerful 
goal system and chunkservers. Nodes and disks can be trivially easily 
added/removed on the fly and chunks will be shuffled, replicated or 
deleted to balance the system. Individual objects can have difference 
goals (replication levels) which can also be changed on the fly and the 
system will rebalance them. Objects can even be changed from/to simple 
replication to Erasure Encoded objects.

I doubt this could be fitted to the existing gluster, but is there 
potential for this sort of thing in Gluster 4.0? I read the design docs 
and they look ambitious.


Lindsay Mathieson

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