Bug 2317735

Summary:	RFE: extend snapdiff API to enable only transferring changed portions of a file
Product:	[Red Hat Storage] Red Hat Ceph Storage	Reporter:	Greg Farnum <gfarnum>
Component:	CephFS	Assignee:	Venky Shankar <vshankar>
Status:	CLOSED ERRATA	QA Contact:	Hemanth Kumar <hyelloji>
Severity:	high	Docs Contact:	Rivka Pollack <rpollack>
Priority:	unspecified
Version:	8.1	CC:	ceph-eng-bugs, cephqe-warriors, hyelloji, jcollin, ngangadh, rpollack, tserlin, vshankar
Target Milestone:	---	Keywords:	FutureFeature
Target Release:	8.1
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	ceph-19.2.1-75.el9cp	Doc Type:	Enhancement
Doc Text:	.`cephfs-mirror` daemon only transfers changed blocks in a file Previously, `cephfs-mirror` daemon would transfer whole files, which is inefficient for large files. With this enhancement, the `cephfs-mirror` daemon uses the blockdiff API in the MDS to only transfer changed blocks in a file. As a result, sync performance is significantly improved in some circumstances, especially for large files.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2025-06-26 12:17:20 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:	2308992
Bug Blocks:	2351689

Description Greg Farnum 2024-10-10 02:49:56 UTC

libcephfs exposes a "snapdiff" API that lets programmatic users query for the list of files changed between two snapshots. This identifies the changed files, but does not identify the changed regions within those files.

RADOS exposes primitives that let you identify the regions which have changed between two snapshots. We should extend the CephFS snapdiff API to additionally let users query for the file diff, by querying the underlying RADOS objects. This should dramatically reduce the amount of data read and transmitted when trying to maintain consistent copies over time.

Comment 1 Storage PM bot 2024-10-10 02:50:07 UTC

Please specify the severity of this bug. Severity is defined here:
https://bugzilla.redhat.com/page.cgi?id=fields.html#bug_severity.

Comment 18 errata-xmlrpc 2025-06-26 12:17:20 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 (Important: Red Hat Ceph Storage 8.1 security, bug fix, and enhancement updates), 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/RHSA-2025:9775