Bob Friesenhahn wrote:
On Tue, 26 May 2009, Frank Middleton wrote:
Just asking if an option for machines with no ecc and their inevitable
memory errors is a reasonable thing to suggest in an RFE.
Machines lacking ECC do not suffer from "inevitable memory errors".
Memory errors are not like death and taxes.
Exactly. My whole point. And without ECC there's no way of knowing.
But if the data is damaged /after/ checksum but /before/ write, then
you have a real problem...
If memory does not work, then you do have a real problem. The ZFS ARC
consumes a large amount of memory. Note that the problem of corruption
around the time of the checksum/write is minor compared to corruption in
the ZFS ARC since data is continually read from the ZFS ARC and so bad
data may be returned to the user even though it is (was?) fine on disk.
This is as close as ZFS comes to having an Achilles' heel. Solving this
problem would require crippling the system performance.
When running a DEBUG kernel (not something most people would do on a
"production" system) ZFS does actually checksum and verify the buffers
in the ARC - not on every access but certain operations cause it to happen.
--
Darren J Moffat
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