From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: On the subject of RAID-6 corruption recovery Date: Mon, 07 Jan 2008 09:20:23 -0800 Message-ID: <47825F57.8000400@zytor.com> References: <4774663C.5090609@zytor.com> <59840.88.217.65.202.1199491167.squirrel@www.e18.physik.tu-muenchen.de> <477EC96D.80505@zytor.com> <51481.88.217.65.202.1199493668.squirrel@www.e18.physik.tu-muenchen.de> <477ED321.6000708@zytor.com> <4781F0AE.7030304@ph.tum.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Mattias Wadenstein Cc: Thiemo Nagel , Linux RAID Mailing List List-Id: linux-raid.ids Mattias Wadenstein wrote: > On Mon, 7 Jan 2008, Thiemo Nagel wrote: > >>> What you call "pathologic" cases when it comes to real-world data are >>> very common. It is not at all unusual to find sectors filled with >>> only a constant (usually zero, but not always), in which case your >>> **512 becomes **1. >> >> Of course it would be easy to check how many of the 512 Bytes are >> really different on a case-by-case basis and correct the exponent >> accordingly, and only perform the recovery when the corrected >> probability of introducing an error is sufficiently low. > > What is the alternative to recovery, really? Just erroring out and > letting the admin deal with it, or blindly assume that the parity is wrong? > Erroring out. Only thing to do at that point. -hpa