Re: PITR Dead horse? - Mailing list pgsql-hackers

From Greg Stark
Subject Re: PITR Dead horse?
Date
Msg-id 87wu3fpoyd.fsf@stark.xeocode.com
Whole thread Raw
In response to Re: PITR Dead horse?  ("scott.marlowe" <scott.marlowe@ihs.com>)
List pgsql-hackers
"scott.marlowe" <scott.marlowe@ihs.com> writes:

> but I'm not sure you can test that without power off tests...  

Well the approach that's been taken manually on the list is to look at the
timing results and conclude they're just physically impossible.

Doing this automatically could be interesting. If the tool were given a
partition to act on directly it would be able to intentionally write to blocks
in reverse order doing an fsync between each block and testing whether the
bandwidth is low enough to conclude a full rotation between each write had
been completed.

Doing the same on the filesystem would be less reliable but might also be an
interesting test since the OS might make fsync lie directly, or might have
some additional intelligence in the filesystem that forces the drive to sync
to the platters before fsync returns.

-- 
greg



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