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Reviving external RAID in the internal drive bays possible?

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Matt Lyon
Reviving external RAID in the internal drive bays possible?
on Jan 16, 2011 at 5:04:54 am

I originally posted this in the FCP forum! I'm not trying to double post, just moving the discussion here:

Hey all,

I have a "house brand" external FW800 RAID from a local shop that recently stopped working. The enclosure consists of two 500 gig Seagate 3.5" 7200 RPM platters.

I suspected the platters still worked, and that it was the power supply/controller that failed, so I tried putting the drives in my Intel Mac's internal drive bays.

Lo and behold, they are spinning up and Disk Utility can see them, but they are being reported as "uninitialized."

Does anyone know if it is possible to rebuild the RAID volume and save the data (I have no reason to suspect it is corrupted). From what I can tell, the enclosure used a hardware RAID 0 controller. So I'm wondering if my only solution is to buy exactly the same controller, put everything back in the external enclosure and cross my fingers.

Thanks,

Matt Lyon
Editor
Toronto

Matt Lyon
Editor
Toronto


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Steve Modica
Re: Reviving external RAID in the internal drive bays possible?
on Jan 16, 2011 at 12:29:45 pm

You would need to know what the raid controller was.

Most raids work by writing special headers on the disks. Each card has it's own format. Even cards with the same chip from different vendors will have different header formats.

When the raid chip sees those headers, it grabs the drives and presents them to the system as a "virtual" device that is the raid. In your case, no chip exists and OS X doesn't recognize the headers, so it just sees bare drives.

One option would be to try powering the external chassis from another supply (probably just a molex connector. You could get some extensions) or you can go find out what raid controller is in the thing and try to find one you can mount internally (this is extremely unlikely).

Since it's probably a good time to migrate anyhow, it's probably a better idea to power the old chassis temporarily, and move everything elsewhere.

Steve Modica
CTO, Small Tree Communications


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David Gagne
Re: Reviving external RAID in the internal drive bays possible?
on Jan 16, 2011 at 4:11:52 pm

R-Studio can do it. You'll need some storage that is twice the size of the raid (for creating images of the drives and for recoverying).


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Matt Lyon
Re: Reviving external RAID in the internal drive bays possible?
on Jan 17, 2011 at 3:14:51 am

Thanks for the input guys!

I'm going to take all the gear back to the shop and see if we can try out a new power supply. Failing that, I'm hoping they have an enclosure kicking around that has the same chipset/firmware (probably a long shot, given the age of the drive).

R-Studio looks like a good tool to have around. In this case, the data in question isn't really worth the cost of buying the software and 2 TB of storage to rebuild the volume onto. So I'll probably end up reformatting and using the drives as internal storage.

Matt Lyon
Editor
Toronto


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Fred Jodry
Re: Reviving external RAID in the internal drive bays possible?
on Jan 17, 2011 at 4:58:34 am

Matt, if you build a new power supply at the shop or repair the original, you have to get the voltages within 2 per cent or better of originals to get the drives to work. It`s one of my tricks that if I want to try to get a bad hard drive to work I sometimes vary the voltages a little, up or down. In computers themselves instead of hook up boxes, swapping power supplies does this.


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Matt Lyon
Re: Reviving external RAID in the internal drive bays possible?
on Jan 20, 2011 at 4:49:17 am

Thanks Fred, I haven't heard that tip before. You vary the voltage a little bit, but within 2%? I guess this gives the drive a little kick start that spurs it into action?

The more I think about it, the more likely it seems that the power supply is to blame. The RAID died a very slow death. First it would take 30 minutes to power up, then a day, then a couple days ... then flatline.

Luckily I got the important stuff off when I noticed the trouble. But It may be a while before I get around to picking up a new power supply, but I'll let you guys know how it works out!

Matt Lyon
Editor
Toronto


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Fred Jodry
Re: Reviving ext RAID , internal bays possible?Here`s why.
on Jan 22, 2011 at 12:11:15 am

1. The electromagnets recording to the spinning magnetic discs are calibrated with what drives them to have enough magnetic power to barely overcome the magnetic hysterysis of whatever was previously there. Usually, magnetic heads on the arms get their gap smeared with use and need a little bit more power. Increasing the voltage to the drives a little is a typical help with age, or heating the top side of the hard drive lowers the hysterysis and accomplishes the practical same. This matter is usually overruled by the next two rules.
2. Playback of what`s magnetically there at the heads and the discs favors lower temperature while, whether the playback amplifiers want higher voltage, lower voltage, or the same voltage as standard, is unknown. Aim a fan at the circuit card if in doubt.
3. This is the strongest rule. The various servos that center the arms on the recording tracks and spin the motor at the right speed, all want to see the centered calibrated voltages supplied. Only age drift changes this a bit.
(Electronic moral: Supplying the original voltages is best. Swapping power supplies and measuring the exact (2) voltages, is a practical way to try subtle sensible voltage differences. Lately I changed a power supply on my new computer because I guessed that the power supply was drooping low on the hard drive and giving a message, "SMART monitoring has determined that your drive is failing. Replace it soon." I replaced the power supply, and won. Fred Jodry


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Matt Lyon
Re: Reviving ext RAID , internal bays possible?Here`s why.
on Jan 30, 2011 at 7:57:13 pm

Success! I put the drives back in the enclosure and we tried out a new power supply in the shop. The drives powered back on instantly and sound pretty healthy. Thanks for everyone's help.

Matt Lyon
Editor
Toronto


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