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From: asami@vader.cs.berkeley.edu (Satoshi Asami)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Qustions about ccd disk driver
Date: 17 Apr 1997 07:29:58 GMT
Organization: CS Div. - EECS, The University of California, Berkeley, CA 94720
Lines: 29
Message-ID: <ASAMI.97Apr17002958@vader.vader.cs.berkeley.edu>
References: <5Y$i$qu@NewsReader.Com>
NNTP-Posting-Host: vader.cs.berkeley.edu
In-reply-to: curt@kcwc.com's message of 15 Apr 1997 15:38:10 GMT
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:39228
In article <5Y$i$qu@NewsReader.Com> curt@kcwc.com (Curt Welch) writes:
* I'm thinking about using the ccd disk driver to set up a striped
* and mirrored news spool. Looking at the code (in 2.1.5), it seems
* that the mirroring function only causes writes to be doubled.
* Reads all go to the first drive in the set, and there seems to be
* no code to read the second drive in case of errors on the first.
* Can anyone confirm this for me? Is anyone using the ccd driver
* in a striped/mirrored configuration for a news spool?
You are absolutely right. If one of the drives fail, you need to take
down the system and:
(1) if you have a replacement drive, put it in (say it's sd5, and the
"good other half" of it is sd0), do a "dd if=/dev/rsd0
of=/dev/rsd5", in single-user mode, then boot the system as
normal, or
(2) if you don't have a replacement drive, take out the CCDF_MIRROR
flag and the second half of the drives in your /etc/ccd.conf
(replace the bad one with the good one, if the failed one was in
the first half, of course), and run it without mirroring until you
get the replacement. Then go to (1).
If someone wants to add hot-spares and other improments to ccd, they
are very welcome. :)
Satoshi