Date: Wed, 05 Mar 2003 19:33:04 +0100 From: Alexander Haderer <alexander.haderer@charite.de> To: freebsd-questions@FreeBSD.ORG Cc: Dirk Emmel <dirk.emmel@charite.de> Subject: vinum: low level access to subdisks / drives Message-ID: <5.2.0.9.1.20030305190047.00b19d80@postamt1.charite.de> In-Reply-To: <5.2.0.9.2.20030305114541.00bd5cb8@mail.servplex.com> References: <200303051245.28192.taxman@acd.net> <5.2.0.9.2.20030305083743.00bcfc80@mail.servplex.com> <3E4A973500003B77@cpfe6.be.tisc.dk> <5.2.0.9.2.20030305083743.00bcfc80@mail.servplex.com>
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Hello,
Here is a vinum question. Assume this setup: Two partitions ad0s1e and
ad2s1e of type vinum with the same size. vinum is set up to use this disks
as RAID 1 (mirror):
drive drive0 device /dev/ad0s1e
drive drive2 device /dev/ad2s1e
volume mirr
plex org concat
sd len 0s drive disk0
plex org concat
sd len 0s drive disk2
newfs has been done and the /dev/vinum/mirr is mounted to /mirr with rw
access. Everything is working without problem.
Because we do not rely on the harddisks and the files at /mirr are accessed
seldom and random, we want to check, if all sectors of the disks ad0 and
ad2 are readable without problem. To do so, we want to run a nightly low
priority cron job that tries to read all sectors of a disk without further
analyzing the data read. The "result" of a failed read (hard disk failure)
will be a kernel message in /var/log/messages, which we monitor 24x7 a day.
Lets say we do dd for reading the sectors:
dd if=/dev/ad0s1 of=/dev/zero bs=1024k
Questions:
1. Will this conflict with vinum or its internal (kernel) data structures
when vinum is running the same time with all components of the RAID 'up'?
2. Will this conflict with parallel read/write access to /mirr ?
3. Should we use "dd if=/dev/vinum/sd/mirr.p0.s0 ..." instead of /dev/ad0s1e ?
with best regards
Alexander
--
Alexander Haderer Charite Berlin - Germany
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