[DOCS-1726] Last modification time for database files could be misleading Created: 19/Jul/13  Updated: 31/Jul/13  Resolved: 19/Jul/13

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

Type: Task Priority: Major - P3
Reporter: Alexander Komyagin 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
Participants:
Days since reply: 10 years, 29 weeks ago

 Description   

On Red Hat Enterprise Linux Server release 5.9 and MongoDB 2.4.5 the last modification time on mongodb data files is not updated when they are flushed. But changing the Operating System to RHEL 6.4, I can see that the last file modification time is updated correctly.

It looks like the 2.6.18 RHEL Linux kernel doesn't conform to:

http://pubs.opengroup.org/onlinepubs/007908799/xsh/mmap.html


The st_atime field of the mapped file may be marked for update at any time between the mmap() call and the corresponding munmap() call. The initial read or write reference to a mapped region will cause the file's st_atime field to be marked for update if it has not already been marked for update.

The st_ctime and st_mtime fields of a file that is mapped with MAP_SHARED and PROT_WRITE, will be marked for update at some point in the interval between a write reference to the mapped region and the next call to msync() with MS_ASYNC or MS_SYNC for that portion of the file by any process. If there is no such call, these fields may be marked for update at any time after a write reference if the underlying file is modified as a result.


However the 2.6.32 version of kernel works as expected. That makes me believe that the issue was caused by the Linux kernel bug and there is no data loss involved, if the file last modification time was the only one inconsistent sign.



 Comments   
Comment by auto [ 31/Jul/13 ]

Author:

{u'username': u'tychoish', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}

Message: DOCS-1726 clarifying v2.2 addUser syntax
Branch: master
https://github.com/mongodb/docs/commit/055cbd5dee162aafc2c8168b97cedd9e804c42ac

Comment by auto [ 31/Jul/13 ]

Author:

{u'username': u'tychoish', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}

Message: DOCS-1726 clarifying v2.2 addUser syntax
Branch: v2.2
https://github.com/mongodb/docs/commit/09eb6ef62aed21633acf04f976183a885aae2f2e

Generated at Thu Feb 08 07:41:45 UTC 2024 using Jira 9.7.1#970001-sha1:2222b88b221c4928ef0de3161136cc90c8356a66.