Bug 1139624

Summary:	[SNAPSHOT]: Chances of running out of memory when number of snapshots in a system increases
Product:	[Red Hat Storage] Red Hat Gluster Storage	Reporter:	Rahul Hinduja <rhinduja>
Component:	snapshot	Assignee:	Anjana Suparna Sriram <asriram>
Status:	CLOSED NOTABUG	QA Contact:	Rahul Hinduja <rhinduja>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	rhgs-3.0	CC:	asriram, jbyers, mzywusko, nsathyan, rhs-bugs, rjoseph, storage-qa-internal
Target Milestone:	---
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:	SNAPSHOT
Fixed In Version:		Doc Type:	Known Issue
Doc Text:	While taking snapshot of a gluster volume, it creates another volume which is similar to the original volume. Gluster volume consumes some amount of memory when it is in started state, so as Snapshot volume. Hence, the system goes to out of memory state. Workaround (if any): Deactivate unused snapshots to reduce the memory foot print.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-01-05 11:16:35 UTC	Type:	Bug
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:
Bug Blocks:	1087818

Description Rahul Hinduja 2014-09-09 11:05:24 UTC

Description of problem:
=======================

Snapshot of a GlusterFS volume creates another volume which will be a point-in-time copy of the original volume, hence end up consuming the resources of the system. In general the memory consumption of the system increases when we increase the number of GlusterFS volume in a system. Same is the case with snap volume, as the number of snapshot increases, they end-up consuming more memory of the system

For example:
============

Memory consumption when only volumes of the systems are created:
================================================================

Without any volumes
Mem:   4054792k total,   257396k used,  3797396k free,    25672k buffers
With 1 volumes 
Mem:   4054792k total,   363128k used,  3691664k free,    25976k buffers
With 2 volumes 
Mem:   4054792k total,   431608k used,  3623184k free,    26264k buffers
With 3 volumes 
Mem:   4054792k total,   507316k used,  3547476k free,    26564k buffers
With 4 volumes 
Mem:   4054792k total,   568644k used,  3486148k free,    26852k buffers
With 5 volumes 
Mem:   4054792k total,   641804k used,  3412988k free,    27144k buffers
With 10 volumes 
Mem:   4054792k total,   983740k used,  3071052k free,    28596k buffers
With 15 volumes
Mem:   4054792k total,  1298564k used,  2756228k free,    30004k buffers
With 20 volumes
Mem:   4054792k total,  1632412k used,  2422380k free,    31420k buffers
With 25 volumes
Mem:   4054792k total,  1984496k used,  2070296k free,    32828k buffers
With 50 volumes
Mem:   4054792k total,  3639772k used,   415020k free,    39688k buffers
With 100 volumes
Mem:   4054792k total,  1795348k used,  2259444k free,     4016k buffers
With 150 volumes 
Mem:   4054792k total,  3217116k used,   837676k free,     2296k buffers
With 200 volumes 
Mem:   4054792k total,  2106916k used,  1947876k free,     1756k buffers
With 250 volumes 
Mem:   4054792k total,  2850944k used,  1203848k free,     1912k buffers
With 275 volumes 
Mem:   4054792k total,  3220232k used,   834560k free,     2784k buffers
With 290 volumes 
Mem:   4054792k total,  3407480k used,   647312k free,     1936k buffers
With 300 volumes 
Mem:   4054792k total,  3489608k used,   565184k free,     6660k buffers


Memory consumption when snaps of a volumes of the systems are created:
======================================================================

Without any snaps
Mem:   4054792k total,   860080k used,  3194712k free,   188024k buffers
With 1 snaps 
Mem:   4054792k total,   879052k used,  3175740k free,   188052k buffers
With 2 snaps 
Mem:   4054792k total,   898164k used,  3156628k free,   188064k buffers
With 3 snaps 
Mem:   4054792k total,   917140k used,  3137652k free,   188088k buffers
With 4 snaps 
Mem:   4054792k total,   937504k used,  3117288k free,   188112k buffers
With 5 snaps 
Mem:   4054792k total,   955672k used,  3099120k free,   188116k buffers
With 10 snaps 
Mem:   4054792k total,  1042620k used,  3012172k free,   188236k buffers
With 15 snaps 
Mem:   4054792k total,  1131396k used,  2923396k free,   188328k buffers
With 20 snaps
Mem:   4054792k total,  1228608k used,  2826184k free,   188432k buffers
With 25 snaps
Mem:   4054792k total,  1321588k used,  2733204k free,   188496k buffers
With 50 snaps
Mem:   4054792k total,  1793884k used,  2260908k free,   189012k buffers
With 100 snaps
Mem:   4054792k total,  2721556k used,  1333236k free,   190300k buffers
With 150 snaps
Mem:   4054792k total,  3637640k used,   417152k free,   192448k buffers
With 200 snaps
Mem:   4054792k total,  3940040k used,   114752k free,     7844k buffers
With 250 snaps
Mem:   4054792k total,  3937340k used,   117452k free,     8164k buffers
With 275 snaps
Mem:   4054792k total,  3946068k used,   108724k free,     7664k buffers
With 290 snaps
Mem:   4054792k total,  3933684k used,   121108k free,     7368k buffers
With 300 snaps
Mem:   4054792k total,  3949112k used,   105680k free,     8544k buffers


Version-Release number of selected component (if applicable):
=============================================================

glusterfs-3.6.0.28-1.el6rhs.x86_64

Comment 4 Shalaka 2014-09-20 11:11:37 UTC

Please review and sign-off edited doc text.

Comment 5 Shalaka 2014-09-26 05:50:58 UTC

Canceling need_info as the text was reviewed and signed-off in online review meeting.

Comment 6 rjoseph 2016-01-05 11:16:35 UTC

Snapshot consumes some amount of memory and as the number of snapshots grow this memory foot print will also grow. With the given glusterd architecture it is not possible to reduce this memory foot print. As part of glusterd 2.0 we will take this up.