Christian,

Adding on to Stahil’s notes, make sure you’re using jumbo MTUs on servers and client host nodes. Making sure you’re using appropriate disk schedulers on hosts and VMs is important, worth double checking that it’s doing what you think it is. If you are only HCI, gluster’s choose-local on is a good thing, but try

cluster.choose-local: false
cluster.read-hash-mode: 3

if you have separate servers or nodes with are not HCI to allow it spread reads over multiple nodes.

Test out these settings if you have lots of RAM and cores on your servers, they work well for me with 20 cores and 64GB ram on my servers with my load:

performance.io-thread-count: 64
performance.low-prio-threads: 32

these are worth testing for your workload.

If you’re running VMs with these, test out libglapi connections, it’s significantly better for IO latency than plain fuse mounts. If you can tolerate the issues, the biggest one at the moment being you can’t take snapshots of the VMs with it enabled as of March.

If you have tuned available, I use throughput-performance on my servers and guest-host on my vm nodes, throughput-performance on some HCI ones. 

I’d test with out the fips-rchecksum setting, that may be creating extra work for your servers.

If you mounted individual bricks, check that you disabled barriers on them at mount if appropriate.

Hope it helps,

  -Darrell

On Mar 24, 2020, at 6:23 AM, Strahil Nikolov <hunter86_bg@yahoo.com> wrote:

On March 24, 2020 11:20:10 AM GMT+02:00, Christian Reiss <email@christian-reiss.de> wrote:
Hey Strahil,

seems you're the go-to-guy with pretty much all my issues. I thank you
for this and your continued support. Much appreciated.


200mb/reads however seems like a broken config or malfunctioning
gluster
than requiring performance tweaks. I enabled profiling so I have real
life data available. But seriously even without tweaks I would like
(need) 4 times those numbers, 800mb write speed is okay'ish, given the
fact that 10gbit backbone can be the limiting factor.

We are running BigCouch/CouchDB Applications that really really need
IO.
Not in throughput but in response times. 200mb/s is just way off.

It feels as gluster can/should do more, natively.

-Chris.

On 24/03/2020 06:17, Strahil Nikolov wrote:
Hey Chris,,

You got some options.
1. To speedup the reads in HCI - you can use the option :
cluster.choose-local: on
2. You can adjust the server and client event-threads
3. You can use NFS Ganesha (which connects to all servers via
libgfapi)  as a NFS Server.
In such case you have to use some clustering like ctdb or pacemaker.
Note:disable cluster.choose-local if you use this one
4 You can try the built-in NFS , although it's deprecated (NFS
Ganesha is fully supported)
5.  Create a gluster profile during the tests. I have seen numerous
improperly selected tests -> so test with real-world  workload.
Synthetic tests are not good.

Best Regards,
Strahil Nikolov

Hey Chris,

What type is your VM ?
Try with 'High Performance' one (there is a  good RH documentation on that topic).

If the DB load  was  directly on gluster, you could use the settings in the '/var/lib/gluster/groups/db-workload'  to optimize that, but I'm not sure  if this will bring any performance  on a VM.

1. Check the VM disk scheduler. Use 'noop/none' (depends on multiqueue is enabled) to allow  the Hypervisor aggregate the I/O requests from multiple VMs.
Next, set 'noop/none' disk scheduler  on the hosts - these 2 are the optimal for SSDs and NVME disks  (if I recall corectly you are  using SSDs)

2. Disable cstates on the host and Guest (there are a lot of articles  about that)

3. Enable MTU 9000 for Hypervisor (gluster node).

4. You can try setting/unsetting the tunables in the db-workload  group and run benchmarks with real workload  .

5.  Some users  reported  that enabling  TCP offload  on the hosts gave huge  improvement in performance  of gluster  - you can try that.
Of course  there are mixed  feelings - as others report  that disabling it brings performance. I guess  it is workload  specific.

6.  You can try to tune  the 'performance.readahead'  on your  gluster volume.

Here are some settings  of some users /from an old e-mail/:

performance.read-ahead: on
performance.stat-prefetch: on
performance.flush-behind: on
performance.client-io-threads: on
performance.write-behind-window-size: 64MB (shard  size)



For a  48 cores / host:

server.event-threads: 4
client.event-threads: 8

Your ecent-threads  seem to be too high.And yes, documentation explains it , but without an example it becomes more confusing.

Best Regards,
Strahil Nikolov
 

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