From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: the " 'official' point of view" expressed by kernelnewbies.org Date: Tue, 15 Aug 2006 15:20:09 -0700 Message-ID: <44E24899.8080201@namesys.com> References: <44E24563.1040900@namesys.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <44E24563.1040900@namesys.com> List-Id: Content-Type: text/plain; charset="us-ascii" To: Edward Shishkin Cc: Tom Reinhart , reiserfs-list@namesys.com Edward Shishkin wrote: > Tom Reinhart wrote: >> Anyone with serious need for data integrity already uses RAID, so why >> add brand new complexity for a solved problem? >> >> RAID is great at recovering data, but not detecting errors. File >> system can detect errors with checksum. What is missing is an API >> between layers for filesystem to say "this sector is bad, go rebuild >> it." >> > > Actually we dont need a special API: kernel should warn and recommend > running fsck, which scans the whole tree and handles blocks with bad > checksums. Yes, but our fsck knows nothing about RAID currently so.... > >> This seems like a much more simple and useful thing than adding ECC >> into the filesystem itself. > > checksumming is _not_ much more easy then ecc-ing from implementation > standpoint, however it would be nice, if some part of errors will get > fixed without massive surgery performed by fsck > > >> >> >>>>> How about we switch to ecc, which would help with bit rot not sector >>>>> loss? >>>> >>>> >>>> >>>> Interesting aspect. >>>> >>>> Yes, we can implement ECC as a special crypto transform that inflates >>>> data. As I mentioned earlier, it is possible via translation of key >>>> offsets with scale factor > 1. >>>> >>>> Of course, it is better then nothing, but anyway meta-data remains >>>> ecc-unprotected, and, hence, robustness is not increased.. >>>> >> >> _________________________________________________________________ >> On the road to retirement? Check out MSN Life Events for advice on >> how to get there! http://lifeevents.msn.com/category.aspx?cid=Retirement >> >> >> > > >