Re: OSD size and performance

Somnath Roy <Somnath.Roy@xxxxxxxxxxx> · Wed, 30 Dec 2015 19:34:39 +0000

Prabu,

I assume you are using krbd then..Could you please let us know the Linux version/flavor you are using ?
Krbd had some hang issues and supposed to be fixed with the latest versions available..Also, it could be due to OCFS2->krbd integration as well (?) ..Handling
 data consistency is the responsibility of OCFS as krbd doesn’t guarantee that..So, I would suggest to do the following to root cause if your cluster is not into production.

1. Do a synthetic fio run  on krbd alone (or creating a filesystem on top) and see if you can reproduce the hang

2. Try building the latest krbd or upgrade your Linux version to get a newer krbd and see if it is still happening.

<< Also we are taking backup from client, we feel that could be the reason for this hang

I assume this is regular filesystem back up ? Why do you think this could be a problem ?

I think it is a client side issue , I doubt it could be because of large OSD size..

Thanks & Regards
Somnath

From: gjprabu [mailto:gjprabu@xxxxxxxxxxxx]

Sent: Wednesday, December 30, 2015 4:29 AM

To: gjprabu

Cc: Somnath Roy; ceph-users; Siva Sokkumuthu

Subject: Re: [ceph-users] OSD size and performance

Hi Somnath,

         Thanks for your reply. Current setup we are having client hang issue and its hang frequently and after reboot it is working, Client used to mount with OCFS2 file system for multiple concurrent client
 access for same data. Also we are taking backup from client, we feel that could be the reason for this hang.

Regards

Prabu

---- On Wed, 30 Dec 2015 11:33:20 +0530
Somnath Roy <Somnath.Roy@xxxxxxxxxxx>wrote ----

FYI , we are using 8TB SSD drive as OSD and not seeing any problem so far. Failure domain could be a concern for bigger OSDs.

Thanks & Regards
Somnath

From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx]
On Behalf Of gjprabu

Sent: Tuesday, December 29, 2015 9:38 PM

To: ceph-users

Cc: Siva Sokkumuthu

Subject: Re: [ceph-users] OSD size and performance

Hi Team,

         Anybody please clarify the below queries.

Regards

Prabu

---- On Tue, 29 Dec 2015 13:03:45 +0530
gjprabu <gjprabu@xxxxxxxxxxxx>wrote ----

Hi Team,

We are using ceph with 3 osd and 2 replicas. Each osd size is 13TB and current data is reached to 2.5TB (each osd). Because of this huge size do we face any problem.

OSD server configuration

Hard disk -- 13TB

RAM -- 96GB 

CPU -- 2 CPU with multi 8 core processor.

Regards

Prabu

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