Bug 1395451 - vfs_cache_pressure at 50 could cause issues
Summary: vfs_cache_pressure at 50 could cause issues
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Storage Console
Classification: Red Hat Storage
Component: ceph-ansible
Version: 2
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: ---
: 2
Assignee: Sébastien Han
QA Contact: Vidushi Mishra
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-11-16 00:06 UTC by Alexandre Marangone
Modified: 2017-06-19 13:15 UTC (History)
10 users (show)

Fixed In Version: ceph-ansible-2.2.1-1.el7scon
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-06-19 13:15:55 UTC
Embargoed:


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Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2017:1496 0 normal SHIPPED_LIVE ceph-installer, ceph-ansible, and ceph-iscsi-ansible update 2017-06-19 17:14:02 UTC

Description Alexandre Marangone 2016-11-16 00:06:07 UTC
Description of problem:
In ceph-ansible we set vfs_cache_pressure at 50 by default. It may create issues if a storage node has a lot of memory and a lot of objects (http://tracker.ceph.com/issues/12405)

I think the reasonable thing to do would be to leave it default (100).

Comment 2 seb 2016-11-16 10:52:34 UTC
How strong is the consensus on this?

Comment 3 Ken Dreyer (Red Hat) 2017-03-03 17:18:46 UTC
Would a core dev please let us know what the optimum behavior is here for ceph-ansible?

Comment 4 Josh Durgin 2017-03-03 17:29:30 UTC
(In reply to Ken Dreyer (Red Hat) from comment #3)
> Would a core dev please let us know what the optimum behavior is here for
> ceph-ansible?

I'd recommend not setting vfs_cache_pressure in ceph-ansible. The syncfs issue is still there, and has caused real problems in the past, whereas there hasn't been good data showing lower vfs_cache_pressure is very helpful - the only cases I'm aware of have shown it makes little difference to performance.

Comment 5 Ken Dreyer (Red Hat) 2017-03-03 18:27:27 UTC
Thanks Josh, PR @ https://github.com/ceph/ceph-ansible/pull/1347

Comment 10 errata-xmlrpc 2017-06-19 13:15:55 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2017:1496


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