[Gluster-users] Slow write times to gluster disk

[Raghavendra Gowdappa]

On Thu, Jun 21, 2018 at 8:41 PM, Pat Haley <phaley at mit.edu> 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 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> wrote:
>>
>>>
>>>
>>> On Thu, Jun 21, 2018 at 8:32 AM, Raghavendra Gowdappa <
>>> 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
>>> [2] https://bugzilla.redhat.com/show_bug.cgi?id=1214489
>>>
>>>
>>>>
>>>>
>>>> On Thu, Jun 21, 2018 at 5:00 AM, Pat Haley <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). Specifically we were testing the suggestions in a
>>>>> recent post (http://lists.gluster.org/pipe
>>>>> rmail/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 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
>>>>>
>>>>> _______________________________________________
>>>>> Gluster-users mailing list
>>>>> Gluster-users at gluster.org
>>>>> http://lists.gluster.org/mailman/listinfo/gluster-users
>>>>
>>>>
>>>>
>>>
>>
>
> --
>
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 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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