Re: OMAP warning ( again )

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I found this discussion between Wido and Florian ( two really good ceph folks ), but it doesn’t seem to deep dive into sharding ( something I would like to know more about ).

https://www.spinics.net/lists/ceph-users/msg24420.html  

None of my clusters are using multi-site sync ( was thinking about it though ).  

Matt:  I see you are talking about this bug report:  http://tracker.ceph.com/issues/34307  

Not sure how I could even find the retired bucket index you are referring to.  I think I understand what sharding is doing, but as far as the inner workings, I am still a newb.

-Brent


-----Original Message-----
From: Matt Benjamin [mailto:mbenjami@xxxxxxxxxx] 
Sent: Saturday, September 1, 2018 2:56 PM
To: Brent Kennedy <bkennedy@xxxxxxxxxx>
Cc: Will Marley <Will.Marley@xxxxxxxxxxxx>; ceph-users <ceph-users@xxxxxxxxxxxxxx>
Subject: Re:  OMAP warning ( again )

Apparently it is the case presently that when dynamic resharding completes, the retired bucket index shards need to be manually deleted.  We plan to change this, but it's worth checking for such objects.  Alternatively, though, look for other large omap "objects", e.g., sync-error.log, if you are using multi-site sync.

Matt

On Sat, Sep 1, 2018 at 1:47 PM, Brent Kennedy <bkennedy@xxxxxxxxxx> wrote:
> I didn’t want to attempt anything until I had more information.  I 
> have been tied up with secondary stuff, so we are just monitoring for 
> now.  The only thing I could find was a setting to make the warning go 
> away, but that doesn’t seem like a good idea as it was identified as 
> an issue that should be addressed.  What perplexes me is that in 
> newest version of Luminous, it should be automatically resharding.  
> Noted here:  https://ceph.com/releases/v12-2-0-luminous-released/
>
> "RGW now supports dynamic bucket index sharding. This has to be enabled via the rgw dynamic resharding configurable. As the number of objects in a bucket grows, RGW will automatically reshard the bucket index in response.  No user intervention or bucket size capacity planning is required."
>
> The documentation, says its enabled by default though, noted here: 
> http://docs.ceph.com/docs/master/radosgw/dynamicresharding
>
> I ran a few of the commands on the buckets to check and the sharding says -1, so what I believe to be the case is that dynamic resharding is only enabled by default on new buckets created in luminous, its not applied to existing buckets.  So now the question is, can I enable dynamic resharding on a particular bucket and will my cluster go nuts if the bucket is huge.  I would rather the system figure out the sharding though as I am unsure what the shard numbers would be should I have to tell the system to do it manually.
>
> There is an open bug report that I have been following: https://tracker.ceph.com/issues/24457 ( appears we are not the only ones ).
>
> We need defined remediation steps for this..... I was thinking of 
> hitting up the IRC room since RGW folks don’t seem to be around :(
>
> -Brent
>
> -----Original Message-----
> From: Will Marley [mailto:Will.Marley@xxxxxxxxxxxx]
> Sent: Friday, August 31, 2018 6:08 AM
> To: Brent Kennedy <bkennedy@xxxxxxxxxx>
> Subject: RE:  OMAP warning ( again )
>
> Hi Brent,
>
> We're currently facing a similar issue. Did a manual reshard repair this for you? Or do you have any more information to hand regarding a solution with this? We're currently sat around scratching our heads about this as there doesn't seem to be much documentation available.
>
> Kind Regards
>
> Will
> Ceph & Openstack Engineer
>
> UKFast.Net Limited, Registered in England Company Registration Number 
> 3845616 Registered office: UKFast Campus, Birley Fields, Manchester 
> M15 5QJ
>
> -----Original Message-----
> From: ceph-users <ceph-users-bounces@xxxxxxxxxxxxxx> On Behalf Of 
> Brent Kennedy
> Sent: 01 August 2018 23:08
> To: 'Brad Hubbard' <bhubbard@xxxxxxxxxx>
> Cc: 'ceph-users' <ceph-users@xxxxxxxxxxxxxx>
> Subject: Re:  OMAP warning ( again )
>
> Ceph health detail gives this:
> HEALTH_WARN 1 large omap objects
> LARGE_OMAP_OBJECTS 1 large omap objects
>     1 large objects found in pool '.rgw.buckets.index'
>     Search the cluster log for 'Large omap object found' for more details.
>
> The ceph.log file on the monitor server only shows the 1 large omap objects message.
>
> I looked further into the issue again and remembered it was related to bucket sharding.  I then remembered that in Luminous it was supposed to dynamic. I went through the process this time of checking to see what the shards were set to for one of the buckets we have and the max shards is still set to 0.  The blog posting about it says that there isn’t anything we have to do, but I am wondering if the same is true for clusters that were upgraded to luminous from older versions.
>
> Do I need to run this: radosgw-admin reshard add --bucket=<bucket> --num-shards=<num_shards>  for every bucket to get that going?
>
> When I look at a bucket ( BKTEST ), it shows num_shards as 0:
> root@ukpixmon1:/var/log/ceph# radosgw-admin metadata get 
> bucket.instance:BKTEST:default.7320.3
> {
>     "key": "bucket.instance:BKTEST:default.7320.3",
>     "ver": {
>         "tag": "_JFn84AijvH8aWXWXyvSeKpZ",
>         "ver": 1
>     },
>     "mtime": "2018-01-10 18:50:07.994194Z",
>     "data": {
>         "bucket_info": {
>             "bucket": {
>                 "name": "BKTEST",
>                 "marker": "default.7320.3",
>                 "bucket_id": "default.7320.3",
>                 "tenant": "",
>                 "explicit_placement": {
>                     "data_pool": ".rgw.buckets",
>                     "data_extra_pool": ".rgw.buckets.extra",
>                     "index_pool": ".rgw.buckets.index"
>                 }
>             },
>             "creation_time": "2016-03-09 17:23:50.000000Z",
>             "owner": "zzzzzzzzzz",
>             "flags": 0,
>             "zonegroup": "default",
>             "placement_rule": "default-placement",
>             "has_instance_obj": "true",
>             "quota": {
>                 "enabled": false,
>                 "check_on_raw": false,
>                 "max_size": -1024,
>                 "max_size_kb": 0,
>                 "max_objects": -1
>             },
>             "num_shards": 0,
>             "bi_shard_hash_type": 0,
>             "requester_pays": "false",
>             "has_website": "false",
>             "swift_versioning": "false",
>             "swift_ver_location": "",
>             "index_type": 0,
>             "mdsearch_config": [],
>             "reshard_status": 0,
>             "new_bucket_instance_id": ""
>
> When I run that shard setting to change the number of shards:
> "radosgw-admin reshard add --bucket=BKTEST --num-shards=2"
>
> Then run to get the status:
> "radosgw-admin reshard list"
>
> [
>     {
>         "time": "2018-08-01 21:58:13.306381Z",
>         "tenant": "",
>         "bucket_name": "BKTEST",
>         "bucket_id": "default.7320.3",
>         "new_instance_id": "",
>         "old_num_shards": 1,
>         "new_num_shards": 2
>     }
> ]
>
> If it was 0, why does it say old_num_shards was 1?
>
> -Brent
>
> -----Original Message-----
> From: Brad Hubbard [mailto:bhubbard@xxxxxxxxxx]
> Sent: Tuesday, July 31, 2018 9:07 PM
> To: Brent Kennedy <bkennedy@xxxxxxxxxx>
> Cc: ceph-users <ceph-users@xxxxxxxxxxxxxx>
> Subject: Re:  OMAP warning ( again )
>
> Search the cluster log for 'Large omap object found' for more details.
>
> On Wed, Aug 1, 2018 at 3:50 AM, Brent Kennedy <bkennedy@xxxxxxxxxx> wrote:
>> Upgraded from 12.2.5 to 12.2.6, got a “1 large omap objects” warning 
>> message, then upgraded to 12.2.7 and the message went away.  I just 
>> added four OSDs to balance out the cluster ( we had some servers with 
>> fewer drives in them; jbod config ) and now the “1 large omap objects”
>> warning message is back.  I did some googlefoo to try to figure out 
>> what it means and then how to correct it, but the how to correct it is a bit vague.
>>
>>
>>
>> We use rados gateways for all storage, so everything is in the 
>> .rgw.buckets pool, which I gather from research is why we are getting 
>> the warning message ( there are millions of objects in there ).
>>
>>
>>
>> Is there an if/then process to clearing this error message?
>>
>>
>>
>> Regards,
>>
>> -Brent
>>
>>
>>
>> Existing Clusters:
>>
>> Test: Luminous 12.2.7 with 3 osd servers, 1 mon/man, 1 gateway ( all 
>> virtual
>> )
>>
>> US Production: Firefly with 4 osd servers, 3 mons, 3 gateways behind 
>> haproxy LB
>>
>> UK Production: Luminous 12.2.7 with 8 osd servers, 3 mons/man, 3 
>> gateways behind haproxy LB
>>
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> ceph-users mailing list
>> ceph-users@xxxxxxxxxxxxxx
>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
>
>
>
> --
> Cheers,
> Brad
>
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-- 

Matt Benjamin
Red Hat, Inc.
315 West Huron Street, Suite 140A
Ann Arbor, Michigan 48103

http://www.redhat.com/en/technologies/storage

tel.  734-821-5101
fax.  734-769-8938
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