[Gluster-users] Slow write times to gluster disk

[Pat Haley]

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 
> <rgowdapp at redhat.com <mailto:rgowdapp at redhat.com>> 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 at redhat.com <mailto:rgowdapp at redhat.com>> wrote:
>
>
>
>         On Thu, Jun 21, 2018 at 8:32 AM, Raghavendra Gowdappa
>         <rgowdapp at redhat.com <mailto:rgowdapp at redhat.com>> 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 <phaley at mit.edu
>             <mailto:phaley at mit.edu>> 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
>
>                 -- 
>
>                 -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>                 Pat Haley Email: phaley at mit.edu <mailto:phaley at mit.edu>
>                 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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>
>
>
>
>

-- 

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  phaley at mit.edu
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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