Bug 2255435

Summary:	[RHCS 6] RFE: change default value of "mds_bal_interval" to "0", aka false
Product:	[Red Hat Storage] Red Hat Ceph Storage	Reporter:	Patrick Donnelly <pdonnell>
Component:	CephFS	Assignee:	Patrick Donnelly <pdonnell>
Status:	CLOSED ERRATA	QA Contact:	Hemanth Kumar <hyelloji>
Severity:	medium	Docs Contact:	Disha Walvekar <dwalveka>
Priority:	unspecified
Version:	5.3	CC:	ceph-eng-bugs, cephqe-warriors, dwalveka, hyelloji, mcaldeir, tserlin, vereddy, vshankar
Target Milestone:	---	Keywords:	FutureFeature
Target Release:	6.1z4
Hardware:	All
OS:	All
Whiteboard:
Fixed In Version:	ceph-17.2.6-187.el9cp	Doc Type:	Enhancement
Doc Text:	Feature: MDS dynamic metadata balancer is off by default. Reason: Poor balancer behavior could fragment trees in undesirable or unintended ways simply by increasing the max_mds file system setting. Result: Operators must turn on the balancer explicitly to use it.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2024-02-08 18:12:00 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2227309
Bug Blocks:	2255436, 2261930

Description Patrick Donnelly 2023-12-20 18:33:14 UTC

This bug was initially created as a copy of Bug #2227309

I am copying this bug because: 

rhcs 6 config fix

Description of problem:  RFE: change default value of "mds_bal_interval" to "0", aka false

From case 03492882 and BZ (https://bugzilla.redhat.com/show_bug.cgi?id=2203258) we see that having "mds_bal_interval" enabled results in performance issue. Beyond the log evidence in BZ 2203258, the customer reports that Ceph FS latency has dropped by 75 percent and I/O in the cluster has doubled since "mds_bal_interval" was set to false on their system.

We'd like to see the change in 5.3z-whatever and 6.1z-whatever and beyond

See also KCS #7026124, (https://access.redhat.com/solutions/7026124)

This same customer commented if this feature hampers performance this much and there is no intention on fixing it, the default value should be changed.


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Comment 9 errata-xmlrpc 2024-02-08 18:12:00 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 (Red Hat Ceph Storage 6.1 Bug Fix update), 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-2024:0747