Re: Brick Reboot => VMs slowdown, client crashes

[Carl Sirotic <csirotic@xxxxxxxxxxxxxxxxxxxx>]

However,

I must have misunderstood the whole concept of gluster.

In a replica 3, for me, it's completely unacceptable, regardless of the options, that all my VMs go down when I reboot one node.

The whole purpose of having a full 3 copy of my data on the fly is suposed to be this.

I am in the process of sharding every file.

But even if the healing time would be longer, I would still expect a non-sharded replica 3 brick with vm boot disk, to not go down if I reboot one of its copy.

I am not very impressed by gluster so far.

Carl

On 2019-08-19 4:15 p.m., Darrell Budic wrote:

/var/lib/glusterd/groups/virt is a good start for ideas, notably some thread settings and choose-local=off to improve read performance. If you don’t have at least 10 cores on your servers, you may want to lower the recommended shd-max-threads=8 to no more than half your CPU cores to keep healing from swamping out regular work.

It’s also starting to depend on what your backing store and networking setup are, so you’re going to want to test changes and find what works best for your setup.

In addition to the virt group settings, I use these on most of my volumes, SSD or HDD backed, with the default 64M shard size:

performance.io-thread-count: 32 # seemed good for my system, particularly a ZFS backed volume with lots of spindles

client.event-threads: 8

cluster.data-self-heal-algorithm: full # 10G networking, uses more net/less cpu to heal. probably don’t use this for 1G networking?

performance.stat-prefetch: on

cluster.read-hash-mode: 3 # distribute reads to least loaded server (by read queue depth)

and these two only on my HDD backed volume:

performance.cache-size: 1G

performance.write-behind-window-size: 64MB

but I suspect these two need another round or six of tuning to tell if they are making a difference.

I use the throughput-performance tuned profile on my servers, so you should be in good shape there.

On Aug 19, 2019, at 12:22 PM, Guy Boisvert <guy.boisvert@xxxxxxxxxxxxxxxx> wrote:

On 2019-08-19 12:08 p.m., Darrell Budic wrote:

You also need to make sure your volume is setup properly for best performance. Did you apply the gluster virt group to your volumes, or at least features.shard = on on your VM volume?

That's what we did here:


gluster volume set W2K16_Rhenium cluster.quorum-type auto
gluster volume set W2K16_Rhenium network.ping-timeout 10
gluster volume set W2K16_Rhenium auth.allow \*
gluster volume set W2K16_Rhenium group virt
gluster volume set W2K16_Rhenium storage.owner-uid 36
gluster volume set W2K16_Rhenium storage.owner-gid 36
gluster volume set W2K16_Rhenium features.shard on
gluster volume set W2K16_Rhenium features.shard-block-size 256MB
gluster volume set W2K16_Rhenium cluster.data-self-heal-algorithm full
gluster volume set W2K16_Rhenium performance.low-prio-threads 32

tuned-adm profile random-io        (a profile i added in CentOS 7)


cat /usr/lib/tuned/random-io/tuned.conf
===========================================
[main]
summary=Optimize for Gluster virtual machine storage
include=throughput-performance

[sysctl]

vm.dirty_ratio = 5
vm.dirty_background_ratio = 2


Any more optimization to add to this?


Guy

--
Guy Boisvert, ing.
IngTegration inc.
http://www.ingtegration.com
https://www.linkedin.com/in/guy-boisvert-8990487

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