Hi,
I recently had a bad experience with NILFS (not the fault of NILFS).
I used NILFS over ISCSI. I had random block corruption during one week,
silently destroying data until NILFS finally crashed. First of all, I
thought about a NILFS bug, so I created a BTRFS volume and restored the
backup from one week earlier to it. After minutes, the BTRFS volume gave
checksum errors, so the culrprit was found, the ISCSI server. For now I
will use BTRFS on my ISCSI volumes to not have the same situation again
even if I would prefer using NILFS due to continuous checkpointing. If I
can remember well, NILFS creates checksums on block writes. It would
really be a good addition to verify these checksums on read, so
corruption of this type would be noticed within minutes instead of days
or possible never if rare enough. I think it has been mentioned earlier
that NILFS checksum are not suitable for file verification but only for
block verification. I think the most important is to know that something
nasty is going on, even if the details aren't known, so I think it would
be a good addition the have some sort of data checksum verification on
read in NILFS.
Bye,
David Arendt
