Messages in this thread | | | Date | Thu, 27 Sep 2018 10:27:38 -0400 | From | "Theodore Y. Ts'o" <> | Subject | Re: POSIX violation by writeback error |
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On Thu, Sep 27, 2018 at 08:43:10AM -0400, Jeff Layton wrote: > > Basically, the problem (as I see it) is that we can end up evicting > uncleanable data from the cache before you have a chance to call fsync, > and that means that the results of a read after a write are not > completely reliable.
Part of the problem is that people don't agree on what the problem is. :-)
The original posting was from someone who claimed it was a "POSIX violation" if a subsequent read returns *successfully*, but then the writeback succeeds.
Other people are worried about this problem; yet others are worried about the system wedging and OOM-killing itself, etc.
The problem is that in the face of I/O errors, it's impossible to keep everyone happy. (You could make the local storage device completely reliable, with a multi-million dollar storage array with remote replication, but then the CFO won't be happy; and other people were talking about making things work with cheap USB thumb drives and laptops. This is the very definition of an over-constained problem.)
- Ted
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