[Gluster-users] Very poor GlusterFS Volume performance (glusterfs 8.2)

Marc Jakobs marc at knusperfisch.de
Mon Nov 9 20:59:26 UTC 2020


I have a GlusterFS Volume on three Linux Servers (Ubuntu 20.04LTS) which
are connected via 1GBit/sec NIC with each other over a dedicated switch.

Every server has a NVMe disk which is used for the GlusterFS Volume
called "data".

When I run a dd performance test directly on the NVMe disk, I get the
following result:

dd if=/dev/zero of=/opt/data/testfile bs=1G count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 1.25716 s, 854 MB/s

When I run the same command on the local mounted GlusterFS, the result
looks like this:

dd if=/dev/zero of=./testfile bs=1G count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 18.5137 s, 58.0 MB/s

or with oflag=sync

dd if=/dev/zero of=./testfile bs=1G count=1 oflag=sync
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 45.1265 s, 23.8 MB/s

I have mounted the Volume like this

mount -t glusterfs -o direct-io-mode=disable /mnt/test/

so it does not even go over the local NIC but instead over the loopback

I have also read a couple of GlusterFS performance tuning web-sites and
set the following options:

gluster vol set data nfs.disable on
gluster volume set data performance.cache-size 1GB
gluster volume set data performance.write-behind-window-size 1GB
gluster volume set data performance.io-thread-count 32
gluster volume set data performance.io-cache on

with no success - the write performance does not change - it stays
exactly at 58.0 MB/sec, which is far far away from the max write speed
of the NVMe disk.

How can I improve the performance? Is this "normal"? From my Google
searches it seems like pretty many people have this problem, but I can
not find information how to dramatically improve the performance.

What write speed do you guys get on your GlusterFS Volumes?

Here are my current Volume "performance" settings.

Thanks for any help! Marc


performance.cache-max-file-size         0
performance.cache-min-file-size         0
performance.cache-refresh-timeout       1
performance.cache-size                  1GB
performance.io-thread-count             32
performance.high-prio-threads           16
performance.normal-prio-threads         16
performance.low-prio-threads            16
performance.least-prio-threads          1
performance.enable-least-priority       on
performance.iot-watchdog-secs           (null)
performance.iot-pass-through            false
performance.io-cache-pass-through       false
performance.cache-size                  1GB
performance.qr-cache-timeout            1
performance.ctime-invalidation          false
performance.flush-behind                on
performance.nfs.flush-behind            on
performance.write-behind-window-size    1GB
performance.strict-o-direct             off
performance.nfs.strict-o-direct         off
performance.strict-write-ordering       off
performance.nfs.strict-write-ordering   off
performance.aggregate-size              128KB
performance.lazy-open                   yes
performance.read-after-open             yes
performance.open-behind-pass-through    false
performance.read-ahead-page-count       4
performance.read-ahead-pass-through     false
performance.readdir-ahead-pass-through  false
performance.md-cache-pass-through       false
performance.md-cache-timeout            1
performance.cache-swift-metadata        false
performance.cache-samba-metadata        false
performance.cache-capability-xattrs     true
performance.cache-ima-xattrs            true
performance.md-cache-statfs             off
performance.nl-cache-pass-through       false
performance.write-behind                on
performance.read-ahead                  off
performance.readdir-ahead               off
performance.io-cache                    on
performance.open-behind                 on
performance.quick-read                  on
performance.nl-cache                    off
performance.stat-prefetch               on
performance.client-io-threads           off
performance.nfs.write-behind            on
performance.nfs.read-ahead              off
performance.nfs.io-cache                off
performance.nfs.quick-read              off
performance.nfs.stat-prefetch           off
performance.nfs.io-threads              off
performance.force-readdirp              true
performance.cache-invalidation          false
performance.global-cache-invalidation   true
performance.parallel-readdir            off
performance.rda-request-size            131072
performance.rda-low-wmark               4096
performance.rda-high-wmark              128KB
performance.rda-cache-limit             10MB
performance.nl-cache-positive-entry     false
performance.nl-cache-limit              10MB
performance.nl-cache-timeout            60

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