[ovirt-users] Very poor GlusterFS performance

[Chris Boot]

Hi folks,

I have 3x servers in a "hyper-converged" oVirt 4.1.2 + GlusterFS 3.10
configuration. My VMs run off a replica 3 arbiter 1 volume comprised of
6 bricks, which themselves live on two SSDs in each of the servers (one
brick per SSD). The bricks are XFS on LVM thin volumes straight onto the
SSDs. Connectivity is 10G Ethernet.

Performance within the VMs is pretty terrible. I experience very low
throughput and random IO is really bad: it feels like a latency issue.
On my oVirt nodes the SSDs are not generally very busy. The 10G network
seems to run without errors (iperf3 gives bandwidth measurements of >=
9.20 Gbits/sec between the three servers).

To put this into perspective: I was getting better behaviour from NFS4
on a gigabit connection than I am with GlusterFS on 10G: that doesn't
feel right at all.

My volume configuration looks like this:

Volume Name: vmssd
Type: Distributed-Replicate
Volume ID: d5a5ddd1-a140-4e0d-b514-701cfe464853
Status: Started
Snapshot Count: 0
Number of Bricks: 2 x (2 + 1) = 6
Transport-type: tcp
Bricks:
Brick1: ovirt3:/gluster/ssd0_vmssd/brick
Brick2: ovirt1:/gluster/ssd0_vmssd/brick
Brick3: ovirt2:/gluster/ssd0_vmssd/brick (arbiter)
Brick4: ovirt3:/gluster/ssd1_vmssd/brick
Brick5: ovirt1:/gluster/ssd1_vmssd/brick
Brick6: ovirt2:/gluster/ssd1_vmssd/brick (arbiter)
Options Reconfigured:
nfs.disable: on
transport.address-family: inet6
performance.quick-read: off
performance.read-ahead: off
performance.io-cache: off
performance.stat-prefetch: off
performance.low-prio-threads: 32
network.remote-dio: off
cluster.eager-lock: enable
cluster.quorum-type: auto
cluster.server-quorum-type: server
cluster.data-self-heal-algorithm: full
cluster.locking-scheme: granular
cluster.shd-max-threads: 8
cluster.shd-wait-qlength: 10000
features.shard: on
user.cifs: off
storage.owner-uid: 36
storage.owner-gid: 36
features.shard-block-size: 128MB
performance.strict-o-direct: on
network.ping-timeout: 30
cluster.granular-entry-heal: enable

I would really appreciate some guidance on this to try to improve things
because at this rate I will need to reconsider using GlusterFS altogether.

Cheers,
Chris

-- 
Chris Boot
bootc at bootc.net