On 05/14/12 11:02, Jan Kara wrote:
However the flush was always available (I think), in fact databases
would not corrupt (not even above ext4 nobarrier, above a raid5
without barriers) if fsync was called at proper times.
This is not true. Both cache flushes and barriers were implemented by
the same mechanism in older kernels. Thus if the device did not properly
propagate the barrier capability, then fsync did not provide any guarantees
in case of power failure (if there are volalile write caches in the storage
device).
Oh! Thanks I had not realized this.
So, if barrier IS provided by the underlying blockdevice but filesystem
is nevertheless mounted as nobarrier (as an explicit option) would
database flushes (fsync) for files on THAT filesystem work properly or not?
Thanks for your insight
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