Fix #4708
closed
MDS: journaler pre-zeroing is dangerous
Added by Greg Farnum about 11 years ago.
Updated about 6 years ago.
Category:
Correctness/Safety
Description
See http://pastebin.com/NJd0UCfF
At first glance it looks like there's a short and a missing log object, and then several of the follow-on objects which did exist got deleted. Perhaps we should be a bit more careful about successfully starting up before pre-zeroing.
(Of course, it's also possible that my quick diagnosis is just wrong, but either way conceptually this is an issue.)
- Description updated (diff)
Possibly related to #6548.
Like Sage said, blacklisting. :)
It's been a while but I think the scenario I envisioned here is one in which the order we spread the blacklist to the OSDs isn't safe enough, so the blacklisted MDS continues writing to some of them but failing to do so on others.
- Priority changed from Normal to High
#6458 could be a result of this issue, so I'm bumping up the priority.
- Tracker changed from Bug to Fix
- Category changed from 47 to Correctness/Safety
- Component(FS) MDS, osdc added
- Target version set to v13.0.0
- Status changed from New to Need More Info
I don't think it's still a problem. new mds takes over a rank after it see old mds is blacklisted in osdmap. There is no way old mds can delete/modify objects that the new mds has modified.
- Status changed from Need More Info to Rejected
- Labels (FS) multimds added
Thanks for explaining Zheng. Closing this.
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