Re: Slow write times to gluster disk

[Pat Haley <phaley@xxxxxxx>]

Hi Raghavendra,

Our technician may have some time to look at this issue tomorrow.  Are there any tests that you'd like to see?

Thanks

Pat

On 06/29/2018 11:25 PM, Raghavendra Gowdappa wrote:

On Fri, Jun 29, 2018 at 10:38 PM, Pat Haley <phaley@xxxxxxx> wrote:

Hi Raghavendra,

We ran the tests (write tests) and I copied the log files for both the server and the client to http://mseas.mit.edu/download/phaley/GlusterUsers/2018/Jun29/ .  Is there any additional trace information you need?  (If so, where should I look for it?)

Nothing for now. I can see from logs that workaround is not helping. fstat requests are not absorbed by md-cache and read-ahead is witnessing them and flushing its read-ahead cache. I am investigating more on md-cache (It also seems to be invalidating inodes quite frequently which actually might be the root cause of seeing so many fstat requests from kernel). Will post when I find anything relevant.

Also the volume information you requested

[root@mseas-data2 ~]# gluster volume info data-volume
 
Volume Name: data-volume
Type: Distribute
Volume ID: c162161e-2a2d-4dac-b015-f31fd89ceb18
Status: Started
Number of Bricks: 2
Transport-type: tcp
Bricks:
Brick1: mseas-data2:/mnt/brick1
Brick2: mseas-data2:/mnt/brick2
Options Reconfigured:
diagnostics.client-log-level: TRACE
network.inode-lru-limit: 50000
performance.md-cache-timeout: 60
performance.open-behind: off
disperse.eager-lock: off
auth.allow: *
server.allow-insecure: on
nfs.exports-auth-enable: on
diagnostics.brick-sys-log-level: WARNING
performance.readdir-ahead: on
nfs.disable: on
nfs.export-volumes: off
[root@mseas-data2 ~]#

On 06/29/2018 12:28 PM, Raghavendra Gowdappa wrote:

On Fri, Jun 29, 2018 at 8:24 PM, Pat Haley <phaley@xxxxxxx> wrote:

Hi Raghavendra,

Our technician was able to try the manual setting today.  He found that our upper limit for performance.md-cache-timeout was 60 not 600, so he used that value, along with the network.inode-lru-limit=50000.

The result was another small (~1%) increase in speed.  Does this suggest some addition tests/changes we could try?

Can you set gluster option diagnostics.client-log-level to TRACE  and run sequential read tests again (with md-cache-timeout value of 60)?

#gluster volume set <volname> diagnostics.client-log-level TRACE

Also are you sure that open-behind was turned off? Can you give the output of,

# gluster volume info <volname>

Thanks

Pat

On 06/25/2018 09:39 PM, Raghavendra Gowdappa wrote:

On Tue, Jun 26, 2018 at 3:21 AM, Pat Haley <phaley@xxxxxxx> wrote:

Hi Raghavendra,

Setting the performance.write-behind off had a small improvement on the write speed (~3%),

We were unable to turn on "group metadata-cache".  When we try get errors like

# gluster volume set data-volume group metadata-cache
'/var/lib/glusterd/groups/metadata-cache' file format not valid.

Was metadata-cache available for gluster 3.7.11? We ask because the release notes for 3.11 mentions “Feature for metadata-caching/small file performance is production ready.” (https://gluster.readthedocs.io/en/latest/release-notes/3.11.0/).

Do any of these results suggest anything?  If not, what further tests would be useful?

Group metadata-cache is just a bunch of options one sets on a volume. So, You can set them manually using gluster cli. Following are the options and their values:

performance.md-cache-timeout=600
network.inode-lru-limit=50000

Thanks

Pat

 

On 06/22/2018 07:51 AM, Raghavendra Gowdappa wrote:

On Thu, Jun 21, 2018 at 8:41 PM, Pat Haley <phaley@xxxxxxx> wrote:

Hi Raghavendra,

Thanks for the suggestions.  Our technician will be in on Monday.  We'll test then and let you know the results.

One question I have, is the "group metadata-cache" option supposed to directly impact the performance or is it to help collect data?  If the latter, where will the data be located?

It impacts performance.

Thanks again.

Pat

On 06/21/2018 01:01 AM, Raghavendra Gowdappa wrote:

On Thu, Jun 21, 2018 at 10:24 AM, Raghavendra Gowdappa <rgowdapp@xxxxxxxxxx> wrote:

For the case of writes to glusterfs mount,

I saw in earlier conversations that there are too many lookups, but small number of writes. Since writes cached in write-behind would invalidate metadata cache, lookups won't be absorbed by md-cache. I am wondering what would results look like if we turn off performance.write-behind.

@Pat,

Can you set,

# gluster volume set <volname> performance.write-behind off

Please turn on "group metadata-cache" for write tests too.

and redo the tests writing to glusterfs mount? Let us know about the results you see.

regards,

Raghavendra

On Thu, Jun 21, 2018 at 8:33 AM, Raghavendra Gowdappa <rgowdapp@xxxxxxxxxx> wrote:

On Thu, Jun 21, 2018 at 8:32 AM, Raghavendra Gowdappa <rgowdapp@xxxxxxxxxx> wrote:

For the case of reading from Glusterfs mount, read-ahead should help. However, we've known issues with read-ahead[1][2]. To work around these, can you try with,

1. Turn off performance.open-behind

#gluster volume set <volname> performance.open-behind off

2. enable group meta metadata-cache
# gluster volume set <volname> group metadata-cache

[1]  https://bugzilla.redhat.com/show_bug.cgi?id=1084508

[2] https://bugzilla.redhat.com/show_bug.cgi?id=1214489

On Thu, Jun 21, 2018 at 5:00 AM, Pat Haley <phaley@xxxxxxx> wrote:

Hi,

We were recently revisiting our problems with the slowness of gluster writes (http://lists.gluster.org/pipermail/gluster-users/2017-April/030529.html). Specifically we were testing the suggestions in a recent post (http://lists.gluster.org/pipermail/gluster-users/2018-March/033699.html). The first two suggestions (specifying a negative-timeout in the mount settings or adding rpc-auth-allow-insecure to glusterd.vol) did not improve our performance, while setting "disperse.eager-lock off" provided a tiny (5%) speed-up.

Some of the various tests we have tried earlier can be seen in the links below.  Do any of the above observations suggest what we could try next to either improve the speed or debug the issue?  Thanks

http://lists.gluster.org/pipermail/gluster-users/2017-June/031565.html
http://lists.gluster.org/pipermail/gluster-users/2017-May/030937.html

Pat

--

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  phaley@xxxxxxx
Center for Ocean Engineering       Phone:  (617) 253-6824
Dept. of Mechanical Engineering    Fax:    (617) 253-8125
MIT, Room 5-213                    http://web.mit.edu/phaley/www/
77 Massachusetts Avenue
Cambridge, MA  02139-4301

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Gluster-users mailing list
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-- 

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  phaley@xxxxxxx
Center for Ocean Engineering       Phone:  (617) 253-6824
Dept. of Mechanical Engineering    Fax:    (617) 253-8125
MIT, Room 5-213                    http://web.mit.edu/phaley/www/
77 Massachusetts Avenue
Cambridge, MA  02139-4301

_______________________________________________
Gluster-users mailing list
Gluster-users@xxxxxxxxxxx
http://lists.gluster.org/mailman/listinfo/gluster-users

-- 

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  phaley@xxxxxxx
Center for Ocean Engineering       Phone:  (617) 253-6824
Dept. of Mechanical Engineering    Fax:    (617) 253-8125
MIT, Room 5-213                    http://web.mit.edu/phaley/www/
77 Massachusetts Avenue
Cambridge, MA  02139-4301

-- 

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  phaley@xxxxxxx
Center for Ocean Engineering       Phone:  (617) 253-6824
Dept. of Mechanical Engineering    Fax:    (617) 253-8125
MIT, Room 5-213                    http://web.mit.edu/phaley/www/
77 Massachusetts Avenue
Cambridge, MA  02139-4301

-- 

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  phaley@xxxxxxx
Center for Ocean Engineering       Phone:  (617) 253-6824
Dept. of Mechanical Engineering    Fax:    (617) 253-8125
MIT, Room 5-213                    http://web.mit.edu/phaley/www/
77 Massachusetts Avenue
Cambridge, MA  02139-4301

-- 

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  phaley@xxxxxxx
Center for Ocean Engineering       Phone:  (617) 253-6824
Dept. of Mechanical Engineering    Fax:    (617) 253-8125
MIT, Room 5-213                    http://web.mit.edu/phaley/www/
77 Massachusetts Avenue
Cambridge, MA  02139-4301

_______________________________________________
Gluster-users mailing list
Gluster-users@xxxxxxxxxxx
https://lists.gluster.org/mailman/listinfo/gluster-users