Re: Moving existing RAID5 disks to an alternate server

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On 20/01/2011 03:05, John Powell wrote:
[...]
Anyhow, the point of my post: Is it really as simple as it sounds? Use
mdadm to recreate the RAID5 volume and away I go? Are there any
details that one can offer that I may need to be aware of or is simply
reading the man pages and various HOWTO's out on the net enough to get
started? Obviously I am taking this slow as the data on the disks is
important to me.

Well, you might be really lucky and find that a few mdadm --examine commands give you all you need to know, or even that whatever distro you run auto-detects and starts your array, but given that the data is valuable, I'd recommend making images of the discs and working with those instead.

First up, use smartctl to check the drives don't have bad sectors. If they do, and perhaps even if they don't, ddrescue or dd_rescue is your friend (I don't know which is better).

Then, if you have another 4 drives of exactly the same size, that's perfect, but you probably don't. If your PATA drives are relatively small, you might be as well dd'ing or dd_rescuing all four drives to images on a new larger SATA drive, then mounting the images via loopback devices.

If you have trouble reading any of the drives for any reason, you might make a backup copy of the image before starting to test it, or look at some previous ideas on this list about making Copy-on-Write devices on top of your loopback devices. This may be paranoia but may be worth reading about, just to give you the option.

Then you can start poking the images with mdadm, dmraid, and perhaps kpartx to activate any partitions, and report back as Neil suggested in his post.

Best of luck.

Cheers,

John.

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