Mailinglist Archive: opensuse (1695 mails)

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Re: [opensuse] 10.2 no RAID to 11.0 RAID 1

----- Original Message -----
From: "Andrew Joakimsen" <joakimsen@xxxxxxxxx>
To: "Brian K. White" <brian@xxxxxxxxx>
Cc: <opensuse@xxxxxxxxxxxx>
Sent: Monday, September 22, 2008 4:05 PM
Subject: Re: [opensuse] 10.2 no RAID to 11.0 RAID 1


On Mon, Sep 22, 2008 at 3:27 PM, Brian K. White <brian@xxxxxxxxx> wrote:

It's perfectly possible to force a rebuild.
In fact, you can force rebuilds in mdadm in situations where no firmware
raid will ever let you.
If you don't know how, that's a you problem not an mdadm problem.

I know how and issue the right command. It say /dev/sdb3 or whatnot
DOES NOT EXSIST.

But if you do ll /dev/sdb3 or even cat /dev/sdb3 the device is obviously
there.

So yes mdadm is crap and should never be used. If you need to do mdadm
/dev/md0 --fail /dev/sdb3 and it say sdb3 do not exist there is a
serious issues of the developers piping their toilets into their code.

Wrong. (Unless you can supply enough exact commands and responses and other
observations to prove your diagnostic process and deductions aren't full of
holes. You have not done so above.)

I have seen a few different things that each were different problems, yet each
could have been described roughly as above, and yet in each case the drive was
not actually unavailable and all desired operations were able to be performed
somehow. The exact steps varied in each case because the exact problem varied
in each case. I don't know which of the exact problems you actually had,
because as I said, there was just in my own little experience more than one way
to get something roughly like that, so I can't say what exactly you could or
should have done that would have worked.

This all assumes good hardware btw. A buggy disk or controller could actually
make a disk appear bad and then later good again or good then lock up etc..
As far as I'm concerned, you could have bad hardware even. You are saying
something doesn't work, but you are not showing your deductive process and so
the claim is meaningless. Send me your problem disks that you think are
impossible to assemble and I bet in a little while I can tell you how to
assemble the array as long as there actually is enough there to use. (if you
did something stupid and blew away metadata that can't be recreated or
inferred, well no hardware raid card will save you from that either.)

And I'm not even slightly an mdadm guru. I simply spent a good solid weekend
and then several smaller incidents experimenting. I would say it's still black
art to me. But even at this level I already have actually performed actions you
claim are impossible, and have seen symptoms like you decribe above, except I
looked at the problem longer than 13 seconds and discovered the problem was not
as it seemed and that it was prfectly solvable in every case so far. That
includes those 10 boxes I was talking about. The disks kept failing randomly,
but it was always possible to rebuild and rejoin them. It sometimes took some
poking and insight. I'm not saying it was always obvious what to do or why.
Just that it always turned out to be do-able even when it looked impossible
based on the first and most obvious commands.

So far my assertion stands. You should not expect mdraid to work for you, but
that has no bearing on other people or on mdraid itself.
You are merely saying that because you don't know how to fly helicopters, that
helicopters are garbage.

I wish any of my machines had any problem right now so I coud show exact
commands myself, but they don't. Including all those impossible mdraid boxes.

Brian K. White brian@xxxxxxxxx http://www.myspace.com/KEYofR
+++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++.
filePro BBx Linux SCO FreeBSD #callahans Satriani Filk!

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