Sorry for double post but I don't know if this mail has been received.

Hello everyone,

I know this issue was already treated on this mailing list. However none of the proposed solutions is satisfying me.

Here is my situation : I've got 3 hyperconverged gluster ovirt nodes, with 6 network interfaces, bounded in bunches of 2 (management, VMs and gluster). The gluster network is on a dedicated bound where the 2 interfaces are directly connected to the 2 other ovirt nodes. Gluster is apparently using it :

   # gluster volume status vmstore
   Status of volume: vmstore
   Gluster process                             TCP Port  RDMA Port
   Online  Pid
   
------------------------------------------------------------------------------
   Brick gluster-ov1:/gluster_bricks
   /vmstore/vmstore                            49152     0 Y       3019
   Brick gluster-ov2:/gluster_bricks
   /vmstore/vmstore                            49152     0 Y       3009
   Brick gluster-ov3:/gluster_bricks
   /vmstore/vmstore

where 'gluster-ov{1,2,3}' are domain names referencing nodes in the gluster network. This networks has 10Gbps capabilities :

   # iperf3 -c gluster-ov3
   Connecting to host gluster-ov3, port 5201
   [  5] local 10.20.0.50 port 46220 connected to 10.20.0.51 port 5201
   [ ID] Interval           Transfer     Bitrate         Retr  Cwnd
   [  5]   0.00-1.00   sec  1.16 GBytes  9.92 Gbits/sec   17    900 KBytes
   [  5]   1.00-2.00   sec  1.15 GBytes  9.90 Gbits/sec    0    900 KBytes
   [  5]   2.00-3.00   sec  1.15 GBytes  9.90 Gbits/sec    4    996 KBytes
   [  5]   3.00-4.00   sec  1.15 GBytes  9.90 Gbits/sec    1    996 KBytes
   [  5]   4.00-5.00   sec  1.15 GBytes  9.89 Gbits/sec    0    996 KBytes
   [  5]   5.00-6.00   sec  1.15 GBytes  9.90 Gbits/sec    0    996 KBytes
   [  5]   6.00-7.00   sec  1.15 GBytes  9.90 Gbits/sec    0    996 KBytes
   [  5]   7.00-8.00   sec  1.15 GBytes  9.91 Gbits/sec    0    996 KBytes
   [  5]   8.00-9.00   sec  1.15 GBytes  9.90 Gbits/sec    0    996 KBytes
   [  5]   9.00-10.00  sec  1.15 GBytes  9.90 Gbits/sec    0    996 KBytes
   - - - - - - - - - - - - - - - - - - - - - - - - -
   [ ID] Interval           Transfer     Bitrate         Retr
   [  5]   0.00-10.00  sec  11.5 GBytes  9.90 Gbits/sec 22            
   sender
   [  5]   0.00-10.04  sec  11.5 GBytes  9.86
   Gbits/sec                  receiver

   iperf Done.

However, VMs stored on the vmstore gluster volume has poor write performances, oscillating between 100KBps and 30MBps. I almost always observe a write spike (180Mbps) at the beginning until around 500MB written, then it drastically falls at 10MBps, sometimes even less (100KBps). Hypervisors have 32 threads (2 sockets, 8 cores per socket, 2 threads per core).

Here is the volume settings :

   Volume Name: vmstore
   Type: Replicate
   Volume ID: XXX
   Status: Started
   Snapshot Count: 0
   Number of Bricks: 1 x 3 = 3
   Transport-type: tcp
   Bricks:
   Brick1: gluster-ov1:/gluster_bricks/vmstore/vmstore
   Brick2: gluster-ov2:/gluster_bricks/vmstore/vmstore
   Brick3: gluster-ov3:/gluster_bricks/vmstore/vmstore
   Options Reconfigured:
   performance.io-thread-count: 32 # was 16 by default.
   cluster.granular-entry-heal: enable
   storage.owner-gid: 36
   storage.owner-uid: 36
   cluster.lookup-optimize: off
   server.keepalive-count: 5
   server.keepalive-interval: 2
   server.keepalive-time: 10
   server.tcp-user-timeout: 20
   network.ping-timeout: 30
   server.event-threads: 4
   client.event-threads: 8 # was 4 by default
   cluster.choose-local: off
   features.shard: on
   cluster.shd-wait-qlength: 10000
   cluster.shd-max-threads: 8
   cluster.locking-scheme: granular
   cluster.data-self-heal-algorithm: full
   cluster.server-quorum-type: server
   cluster.quorum-type: auto
   cluster.eager-lock: enable
   performance.strict-o-direct: on
   network.remote-dio: off
   performance.low-prio-threads: 32
   performance.io-cache: off
   performance.read-ahead: off
   performance.quick-read: off
   auth.allow: *
   user.cifs: off
   storage.fips-mode-rchecksum: on
   transport.address-family: inet
   nfs.disable: on
   performance.client-io-threads: on

When I naively write directly on the logical volume, which is mounted on a material RAID5 3-disks array, I have interesting performances:

   # dd if=/dev/zero of=a bs=4M count=2048
   2048+0 records in
   2048+0 records out
   8589934592 bytes (8.6 GB, 8.0 GiB) copied, 17.2485 s, 498 MB/s
   #urandom gives around 200MBps

Moreover, hypervisors have SSD which have been configured as lvcache, but I'm unsure how to test it efficiently.

I can't find where is the problem, as every piece of the chain is apparently doing well ...

Thanks anyone for helping me :)

--
téïcée <https://www.teicee.com/?pk_campaign=Email>        *Mathieu Valois*

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