From: Aryeh Leib Taurog <vim@aryehleib.com>
To: linux-raid@vger.kernel.org
Subject: Re: Reassembling RAID1 after good drive was offline [newbie]
Date: Sun, 4 Jan 2015 12:20:09 +0200 [thread overview]
Message-ID: <20150104102009.GA4511@deb76.aryehleib.com> (raw)
In-Reply-To: <54A6E5B1.2090602@tigertech.com>
On Fri, Jan 02, 2015 at 6:38 PM, Robert L Mathews wrote:
> Your question is about how to reassemble them without a resync,
> which is understandable, but the reason md isn't doing that
> automatically is that it thinks they might be different.
> I personally would always do a resync in such a case. A flaky cable
> suggests that data on it is suspect, and this is one of the things
> RAID 1 is for: it allows you to copy clean data to suspect
> partitions.
> But I'm known to be data-paranoid. Other people may have different
> opinions/suggestions.
Thanks. I tend to agree. Would the resync just copy all the data
from the "good" drive back to the "failed" drive? For diagnostic
purposes, it would actually be a lot more informative to compare the
two drives and see if there really is data corruption on one of them
or not. Is there a way to do that? If I were to demonstrate that the
data are in sync, I would want to reassemble without resync.
Also, in my situation, since for now I'm just using a pair of external
drives, I could easily imagine accidentally trying to assemble the
array when one of the drives is powered down. Then this situation
would arise again without faulty hardware. I suppose an 'assemble'
script could help protect against the latter case by checking first
that both devices are available.
Prudence notwithstanding, I do think there are valid cases for
reassembling this array without resync. If there's a way to do that,
I'd still like to know.
With appreciation,
Aryeh Leib Taurog
next prev parent reply other threads:[~2015-01-04 10:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-01 17:40 Reassembling RAID1 after good drive was offline [newbie] Aryeh Leib Taurog
2015-01-01 20:54 ` Robert L Mathews
2015-01-02 11:01 ` Anthonys Lists
2015-01-02 14:02 ` Aryeh Leib Taurog
2015-01-02 13:01 ` Aryeh Leib Taurog
2015-01-02 18:38 ` Robert L Mathews
2015-01-04 10:20 ` Aryeh Leib Taurog [this message]
2015-01-04 11:10 ` Peter Grandi
2015-01-04 21:07 ` Aryeh Leib Taurog
2015-01-04 21:45 ` Wols Lists
2015-01-05 17:25 ` Robert L Mathews
2015-01-05 18:54 ` NeilBrown
2015-01-07 8:30 ` Aryeh Leib Taurog
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