[DOCS-1212] Mention the bug related to Linux, xfs and rsync on /manual/administration/backups/ page Created: 08/Mar/13  Updated: 30/Oct/23  Resolved: 07/Feb/15

Status: Closed
Project: Documentation
Component/s: Server
Affects Version/s: None
Fix Version/s: Server_Docs_20231030

Type: Improvement Priority: Trivial - P5
Reporter: Juho Mäkinen Assignee: Unassigned
Resolution: Won't Fix Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
related to SERVER-8518 Recovering slave with journal causes ... Closed
Participants:
Days since reply: 10 years, 49 weeks, 1 day ago

 Description   

In relation of the bug https://jira.mongodb.org/browse/SERVER-8518 I'm proposing a following note to the page http://docs.mongodb.org/manual/administration/backups/

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Nearly all Linux kernel versions up to 2.6.32 suffers a bug https://bugzilla.kernel.org/show_bug.cgi?id=2645 which in some cases delays the mtime (modification timestamp) update for the mongodb data files when using the XFS filesystem. Also other filesystems might be affected in older Linux versions. This delay might cause rsync to ignore some data files if rsync is used to make backups.

You can verify if you might be affected by this bug by compiling and running this test script https://bugzilla.kernel.org/attachment.cgi?id=14430

Always remember to test and practice backup recovery, so you can be sure you have a working backup method.



 Comments   
Comment by Juho Mäkinen [ 12/Mar/13 ]

No. The --ignore-times will basically make the rsync to crawl thru all files (just as --checksum), which will severely hurt the restoration performance. For example in my case the process took about four hours on a dataset of 180GB, which you don't want to wait when you're restoring your critical service from backups.

Comment by Sam Kleinman (Inactive) [ 11/Mar/13 ]

Is the -I (--ignore-times) option to rsync a viable work around for this issue?

Comment by Juho Mäkinen [ 08/Mar/13 ]

Also a link can be added to my blog post explaining the details of this issue: http://www.juhonkoti.net/2013/03/06/snapshot-recovery-problems-with-mongodb-mmap-xfs-filesystem-and-rsync

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