Dear Strahil,
thank you very much for your response. After some testing,
the brick performance was much lower than expected. A previous
benchmarking procedure
at the beginning does not point that out. In our case with real life
data, even with a minor
number of directories and files, a simple ls -l command on the **brick**
itself
take up to 16 seconds (4 seconds in general, but 16s was the worst case
we observed).
We decided to reconfigure the bricks from raid6 to raid10
using the reset-brick command, see section 11.9.5 as reference:
https://access.redhat.com/documentation/en-us/red_hat_gluster_storage/3.5/html/administration_guide/sect-migrating_volumes#sect-Migrating_Volumes-Reconfigure_Brick
This re-configuring worked perfect and self-healing is almost done now
(b.t.w. 2TB/day self-healing performance is normal?).
Since the bricks shows acceptable raid10 performance (at least for our
current workload), the performance on the fuse-mountpoint
on the dispersed volume (4+2) is lower than the brick performance. Maybe
I am wrong, I was going to expect at least
a slightly higher performance than the brick-performance.
Other example:
Just for testing purposes, I created a distributed volume (sharding on)
on the some storage nodes that consists of 2 NVME's / per node (i.e. 6
in total).
A simple rsync command of a single large file provides 222.25M
bytes/sec on a fuse-mount-point of this distributed volume.
The same command, executed on the brick itself provides 265.19M
bytes/sec. As before,
the performance is lower than the individual brick performance. Is this
a normal behavior or
or what can be done to improve the single client performance as pointed
out in this case?
Regards,
Felix
On 20/02/2020 22:26, Strahil Nikolov wrote:
On February 20, 2020 10:39:47 PM GMT+02:00, "Felix Kölzow" <felix.koelzow@xxxxxx> wrote:
Dear Gluster-Experts,
we created a three-node setup with two bricks each and a dispersed
volume that can be
accessed via the native client (glusterfs --version = 6.0).
The nodes are connected via 10Gbps (cat6,bonding mode 6).
If we running a performance test using the smallfile benchmark tool,
./smallfile_cli.py --top ~/test6/ --file-size 16384 --threads 8 --files
1000 --response-times y --operation create
we observing the
behavior as shown in the attached figure. For a short time, we can
almost saturated the 10Gbps but
then immediately network traffic is dropping almost to zero for about 5
to 25 seconds.
Actually, we don't have any glue what does causes this strange
behavior.
We had a lot of
reconfigured volume options and now we are starting from scratch, i.e.
gluster volume reset dispersed_fuse all
and the current options looks like:
Volume Name: dispersed_fuse
Type: Disperse
Volume ID: 45d3c7c9-526f-45ea-9930-ee7a2274a220
Status: Started
Snapshot Count: 1
Number of Bricks: 1 x (4 + 2) = 6
Transport-type: tcp
Bricks:
Brick1: mimas:/gluster/vg00/dispersed_fuse/brick
Brick2: enceladus:/gluster/vg00/dispersed_fuse/brick
Brick3: tethys:/gluster/vg00/dispersed_fuse/brick
Brick4: mimas:/gluster/vg01/dispersed_fuse/brick
Brick5: enceladus:/gluster/vg01/dispersed_fuse/brick
Brick6: tethys:/gluster/vg01/dispersed_fuse/brick
Options Reconfigured:
client.event-threads: 16
server.event-threads: 16
performance.io-thread-count: 16
geo-replication.ignore-pid-check: on
geo-replication.indexing: on
features.quota: off
features.inode-quota: off
nfs.disable: on
storage.fips-mode-rchecksum: on
server.outstanding-rpc-limit: 512
server.root-squash: off
cluster.server-quorum-ratio: 51%
cluster.enable-shared-storage: enable
Any hints for root cause analysis are appreciated.
Please let me know if you need more information.
Kind Regards,
Felix
Hi Felix,
Usually for performance issues the devs need a little bit more details.
In your case you can :
1. Test with real workload - as this is what you are going to do with the Gluster. If that is not possible, you can run the synthetic benchmark focusing on the workload that is closest to the real one.
2. Check the groups of options in /var/lib/gluster/groups . There is a 'profile' group for DB, Virtualization, small file workloads, etc . Play with those settings and adjust as necessary.
3. Obtain a gluster profile and use the 'top' command to gain more information about the pool's status.
For details, check https://docs.gluster.org/en/latest/Administrator%20Guide/Monitoring%20Workload/
This information will allow more experienced adminiatrators and the developers to identify any pattern that could cause the symptoms.
Tuning Gluster is one of the hardest topics, so you should prepare yourself for a lot of test untill you reach the optimal settings for your volumes.
Best Regards,
Strahil Nikolov
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