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?

Thanks again.

Pat


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


On Thu, Jun 21, 2018 at 10:24 AM, Raghavendra Gowdappa <[email protected] <mailto:[email protected]>> 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
    <[email protected] <mailto:[email protected]>> wrote:



        On Thu, Jun 21, 2018 at 8:32 AM, Raghavendra Gowdappa
        <[email protected] <mailto:[email protected]>> 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
        <https://bugzilla.redhat.com/show_bug.cgi?id=1084508>
        [2] https://bugzilla.redhat.com/show_bug.cgi?id=1214489
        <https://bugzilla.redhat.com/show_bug.cgi?id=1214489>




            On Thu, Jun 21, 2018 at 5:00 AM, Pat Haley <[email protected]
            <mailto:[email protected]>> 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
                
<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
                
<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-June/031565.html>
                
http://lists.gluster.org/pipermail/gluster-users/2017-May/030937.html
                
<http://lists.gluster.org/pipermail/gluster-users/2017-May/030937.html>

                Pat

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                Pat Haley Email: [email protected] <mailto:[email protected]>
                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/
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-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  [email protected]
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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