From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 15 Oct 2008 20:37:15 +0200 From: Christian Kellermann To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Message-ID: <20081015183715.GF1296@hermes.my.domain> References: <20081015082813.GD1296@hermes.my.domain> <4ac626d7ca823fb7e05c3f2dcb03a131@lsub.org> <20081015084718.GE1296@hermes.my.domain> <13426df10810150848x659a9671w7e562a20ee2a61e0@mail.gmail.com> <14ec7b180810150854i575d0f90qafc949b928613e3c@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.16 (2007-06-09) Cc: mirtchovski@gmail.com Subject: Re: [9fans] How to get the diagnostics of fs(3) Topicbox-Message-UUID: 1ec1355e-ead4-11e9-9d60-3106f5b1d025 * erik quanstrom [081015 18:23]: > > back when i had mirroring via devfs (some three years ago now) i used > > 'cmp' to verify that the disks were being correctly written to and > > that no errors have occurred. i ran cmp from the nigtly log at least > > couple of times a week. > > that's a good idea. > > when using the mirror device, no write error is issued unless all mirrored > copies are unwritable. this would make me nervous since without a > checksum, it's hard to know which copy is good. > > (/n/sources/plan9/sys/src/9/port/devfs.c:697) Also it means that while the writes may be ok, you will find out that some sectors are corrupt at the wrong time. For this a cmp would not be sufficient would it? An interesting thing in my case is that I got cmp errors from the start, even with freshly nulled partitions and identical partitions and disks. I still cannot figure out why. Cheers, Christian