On 08/19/2009 09:39 PM, Mark Lord wrote:
[resending, after fixing the Cc: list; somebody trimmed it earlier]
Jamie Lokier wrote:
..
I don't remember - does TRIM guarantee the blocks read zeros afterwards?
..
No, it doesn't.
A drive can optionally support "deterministic TRIM", whereby it will
return
consistent data for any given trimmed sector afterwards, but that
doesn't mean zeros.
-ml
Note that returning consistent data is critical for devices that are
used in a RAID group since you will need each RAID block that is used to
compute the parity to continue to return the same data until you
overwrite it with new data :-)
If we have a device that does not support this (or is misconfigured not
to do this), we should not use those devices in an MD group & do discard
against it...
ric
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