[Gluster-users] Gluster tier in progress after attach

[Nithya Balachandran]

Please check the rebalance log to see why those files were not migrated.

Regards,
Nithya

On 24 September 2018 at 21:21, Jeevan Patnaik <g1patnaik at gmail.com> wrote:

> Hi,
>
> Yes, I did. The status shows all as completed.
>
> Regards,
> Jeevan.
>
> On Mon 24 Sep, 2018, 9:20 PM Nithya Balachandran, <nbalacha at redhat.com>
> wrote:
>
>>
>>
>> On 24 September 2018 at 21:01, Jeevan Patnaik <g1patnaik at gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> What do you mean by expanding volume?
>>>
>>> I mean adding new bricks to extend storage. It is mentioned that
>>> detaching tier is must for adding or removing bricks.
>>>
>>> What command did you use to detach the tier? And how did you check that
>>> the files still exist on the hot tier?
>>>
>>> gluster volume tier volume_name detach start
>>>
>>> I check the files directly from backend filesystem on disk and there are
>>> still left over files on all hot tier disks.
>>>
>>> Anyhow I proceeded with detach commit to see what would happen..so after
>>> commit, I can't access those files from client filesystems..so they're gone
>>> with the hot tier and were not moved to cold tier.
>>>
>>
>> Did you check that the detach tier operation had completed before running
>> detach commit?
>>
>>>
>>> And even if I try to attach the hot tier bricks again to bring back the
>>> files, attach won't work with existing files.
>>>
>>> So, it seems we shouldn't detach hot tier without making sure all files
>>> are moved to cold tier..but in my case, some files just won't move, even
>>> though they aren't being accessed anywhere.
>>>
>>
>>
>>
>>>
>>> There's a statement saying POSIX locks can cause files to be still left
>>> in hot tier and in that case, either the application causing posix lock has
>>> to be closed or files should be moved manually (but where?)... however, I
>>> don't think in my case there's any posix locks as the files are not
>>> accessed by any application except gluster itself.
>>>
>>> Regards,
>>> Jeevan.
>>>
>>>
>>> On Mon 24 Sep, 2018, 8:45 PM Nithya Balachandran, <nbalacha at redhat.com>
>>> wrote:
>>>
>>>> It has been a while since I worked on tier but here is what I remember:
>>>>
>>>>
>>>> On 24 September 2018 at 19:15, Jeevan Patnaik <g1patnaik at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi Nithya,
>>>>>
>>>>> No..the files are not being accessed. And tiering mode is in cache
>>>>> mode and what I understood is in cache mode every file is moved to hot tier
>>>>> until it reaches low watermark, then it only promotes highly accessed files.
>>>>>
>>>>> Not quite . All files will initially exist on the cold tier. Any new
>>>> files will be created on the hot tier. Any old files that are accessed will
>>>> be promoted ot the hot tier.
>>>>
>>>>
>>>> And do you mean everytime we expand volume,  we are virtually flushing
>>>>> the tier and it regenerates only when a files are accessed?
>>>>>
>>>>> What do you mean by expanding the volume?
>>>>
>>>>
>>>>> Also I see one more issue now, I hav generated another 1000 files
>>>>> after tiering is started and I see all 1000 files are now created on hot
>>>>> tier. Now, I detached again..in detach status it shows completed..but when
>>>>> I checked, around 260 files are still located on hot tier..those files are
>>>>> not being used anywhere..ca you tell why are they still not moved to cold
>>>>> tier and why the detach status is showing a wrong status.
>>>>>
>>>>
>>>> What command did you use to detach the tier? And how did you check that
>>>> the files still exist on the hot tier?
>>>>
>>>> Regards,
>>>> Nithya
>>>>
>>>>>
>>>>> I am using gluster 3.12.3 and server hosts include RHEL 6.7 and 7.2
>>>>> hosts also.
>>>>>
>>>>> Regards,
>>>>> Jeevan.
>>>>>
>>>>> On Mon 24 Sep, 2018, 7:00 PM Nithya Balachandran, <nbalacha at redhat.com>
>>>>> wrote:
>>>>>
>>>>>> Are those files being accessed? Tiering will only promote those that
>>>>>> have been accessed recently.
>>>>>>
>>>>>> Regards,
>>>>>> Nithya
>>>>>>
>>>>>> On 24 September 2018 at 18:32, Jeevan Patnaik <g1patnaik at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> I see it still not promoting any files. Do we need to run any
>>>>>>> command to force the movement?
>>>>>>>
>>>>>>> This would be an issue if we need to expand disk as then we also
>>>>>>> need to detach existing tier and attach again and expect the data to be
>>>>>>> promoted to the hot tier.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Jeevan.
>>>>>>>
>>>>>>> On Mon 24 Sep, 2018, 6:17 PM Jeevan Patnaik, <g1patnaik at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I have created a 18 disk replica 3 volume and created 1000 random
>>>>>>>> files each of 10M.
>>>>>>>>
>>>>>>>> Later I have attached 15 disk replica 3 tier with each hot tier
>>>>>>>> disk coming from cold tier host, except on 3 (as we don't have hot tier
>>>>>>>> disk)
>>>>>>>>
>>>>>>>> After attach, I see no files are promoted at even after 15 minutes.
>>>>>>>> Status is showing as In progress.
>>>>>>>>
>>>>>>>> Is it always this much slow? For 10G data, 15 minutes is too much
>>>>>>>> Also will the data try to be promoted to a hot tier coming from the
>>>>>>>> same host to reduce the time taken to move the files?
>>>>>>>>
>>>>>>>> Cold tier is made of RAID supported SSD and hot tier is made of
>>>>>>>> NVMe SSDs.
>>>>>>>>
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Jeevan.
>>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Gluster-users mailing list
>>>>>>> Gluster-users at gluster.org
>>>>>>> https://lists.gluster.org/mailman/listinfo/gluster-users
>>>>>>>
>>>>>>
>>>>>>
>>>>
>>
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