From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Youngman Subject: Re: Bit-Rot Date: Fri, 3 Mar 2017 21:41:24 +0000 Message-ID: <95588e39-f42e-54d4-e7ff-a70af51a77c1@youngman.org.uk> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Gandalf Corvotempesta , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 03/03/17 21:25, Gandalf Corvotempesta wrote: > Hi to all > Wouldn't be possible to add a sort of bitrot detection on mdadm? > I know that MD is working on blocks and not files, but checksumming a > block should still be possible. > > In example, if you read some blocks with dd, you can still hash the > content and verify that on next read/consistency check Isn't that what raid 5 does? Actually, iirc, it doesn't read every stripe and check parity on a read, because it would clobber performance. But I guess you could have a switch to turn it on. It's unlikely to achieve anything. Barring bugs in the firmware, it's pretty near 100% that a drive will either return what was written, or return a read error. Drives don't return dud data, they have quite a lot of error correction built in. Cheers, Wol