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RAID Array: unplugging disk bad?
Fail Medic
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#1
04-14-2009, 01:00 PM

I looked around and I get mostly the discussions on the RAID levels and I'm rolling my eyes, so I'd figure maybe I could just ask y'all:

I have a RAID controller that starts up during POST.  I have one disk by itself, and I have two other disks in RAID-0 (striping).  If I unplug the disks that are striped and temporarily plug in another, and THEN put those two disks back, will it be like nothing happened?  I guess I'm asking this: the actual definitions and pointers and stuff are on the disks, yes?  If the two disks see each other then they're happy and the RAID controller sees they're happy and it's happy, yes?  Even after physically removing them from the host PC and then reconnecting them?

I have a suspect disk that I want to test.  I plan on using a Ubuntu Live CD and peeking at the suspect through that instead of loading up Windows and watching it wonder where my original disks are but I don't want to break their magical "RAID link" and make the striped disks unreadable.

Guidance appreciated, thanks.
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HeK
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#2
04-14-2009, 07:07 PM

Hrm...

A lot of this depends on how your 'RAID controller' works. If it's a standard consumer on-board model, it will likely look for array drives at the physical ports. Meaning if you swap out your two array drives the 'RAID BIOS' will think you have lost a drive.

The RAID bios should store the stripe size and geometry information. If you record this in advance, you can technically rebuild the array without writing anything to the drives.

What you will have to do is disconnect the drives (marking which is drive 0 and which is drive 1), boot up and break the array. Then you can connect your single drive.

The tricky part will be going backwards. You will have to recreate the array, and you should only be able to create an array with the two drives attached. You will have to hope that it does not initialize the array and wipe your data.

If your Raid controller works like a proper, server class controller.... then prey, cause they are far more complex.
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Fail Medic
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#3
04-14-2009, 07:20 PM

Hmm.  I'd rather it not screw anything up.  I do have a backup of the striped array, but it'd be bothersome.  And it sounds like this is bad vibe country.  What I've got is very likely standard consumer on-board fare.

Thanks for response, Hek.  I'm going to go a different route besides swapping my drives like a SATA > USB thingie or something.
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HeK
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#4
04-14-2009, 07:42 PM

That is your best bet, unless you need direct hardware-level access for data recovery. At which point your mileage will vary based on your USB SATA controller.

General rule of RAID arrays is to proceed with caution.
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at0m
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#5
05-08-2009, 11:06 AM

Quote:RAID Array: unplugging disk bad?
Yes, it is bad. Don't do it.



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Fail Medic
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#6
05-08-2009, 06:15 PM

(05-08-2009, 11:06 AM)at0m link Wrote:
Quote:RAID Array: unplugging disk bad?
Yes, it is bad. Don't do it.

I didn't.  I watched Hek's link and decided to choose life over fucking with RAID arrays. 

Oh, and that suspect disk was tried in a USB thingie and wouldn't spin up, so fuck it!
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HeK
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#7
05-08-2009, 11:43 PM

In relation to RAID arrays, some fucktards moved one of my EVA SANs without diagramming it.
So needless to say, I lost disk arrangements on 80 146GB FC drives.

Luckily I didn't have any production data on it, but now I gotta go back and recreate all the LUNs.
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