From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Arendt Subject: read checksum verification Date: Wed, 12 Jul 2023 20:32:13 +0200 Message-ID: <174f995c-e794-74c4-24d6-52451f3f3f28@prnet.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Content-Language: en-US List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org 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