Right. I'd also like to just add that in its current form, sharding does not support zerofill and discard operations and their development is underway.
As far as fallocate is concerned, it should be possible to use the operation on a sharded volume if it is invoked through posix_fallocate() API.
Also, in our testing we have found 512MB shard size to provide good performance as far as both IO and self-heal are concerned. I hope that works for you too!
-Krutika
From: "Lindsay Mathieson" <lindsay.mathieson@xxxxxxxxx>
To: "Krutika Dhananjay" <kdhananj@xxxxxxxxxx>, "Bello Florent" <florent.bello@xxxxxxxxxxxxxxx>
Cc: gluster-users@xxxxxxxxxxx
Sent: Thursday, January 21, 2016 6:22:09 AM
Subject: Re: [Gluster-users] Shard in productionHeh, thanks Krutika.
I believe its pretty much there, have been stress testing it on our production VM cluster for weeks, though not with critical VM's. It is a huge improvement when for the heal process when dealing with large VM's. Failure modes have been very reliable to.
Nb. All my testing has been VM's - e.g a few large files with only one process accessing them. I can't speak to the many thousands of dirs/files use case.
If you are using it for VM hosting (as you are) then it is essential that you set the "virt" group properties, other wise you will end up with VM corruption. These are the settings I've evolved over my testing:
Options Reconfigured:
performance.readdir-ahead: off
features.shard: on
features.shard-block-size: 512MB
cluster.self-heal-window-size: 256
server.event-threads: 4
client.event-threads: 4
cluster.quorum-type: auto
cluster.server-quorum-type: server
performance.low-prio-threads: 32
performance.io-thread-count: 32
performance.cache-refresh-timeout: 4
nfs.disable: on
nfs.addr-namelookup: off
nfs.enable-ino32: off
performance.write-behind: off
performance.strict-write-ordering: on
performance.stat-prefetch: off
performance.quick-read: off
performance.read-ahead: off
performance.io-cache: off
cluster.eager-lock: enable
network.remote-dio: enable
cluster.data-self-heal-algorithm: full
On 21/01/16 02:06, Krutika Dhananjay wrote:Adding Lindsay Mathieson, who has tested sharding with VM store extensively. :)-KrutikaFrom: "Bello Florent" <florent.bello@xxxxxxxxxxxxxxx>
To: gluster-users@xxxxxxxxxxx
Sent: Wednesday, January 20, 2016 8:12:27 PM
Subject: Shard in productionHi,
i see recently the Shard feature is reached to stable. Soon, i want to install oVirt with Gluster Replica Storage and i guess shard feature is good for me. Can i use this feature for my VM Storage production or you guess it's not mature ?
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-- Lindsay Mathieson
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