Mailinglist Archive: opensuse (818 mails)

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Re: [opensuse] Recover Linux Raid 0 with 2x2port 3Ware Raid 1 cards
On 9/1/2011 5:14 PM, Joaquin Sosa wrote:
On Thu, Sep 1, 2011 at 12:29, John Andersen<jsamyth@xxxxxxxxx> wrote:
software raid for the ease
of ... disk replacement.

How is that? Just the other day I replaced a failed SCSI drive in an
HP server with the onboard RAID controller. You remove the failed
drive while the system is running, and that is it.

If it was a Linux software RAID I would have to run commands and hope
they were correct.

It was only easy because you were wise and planned ahead and were lucky that your planning worked. Meaning lucky the special spare drive wasn't lost or damaged in all the time it was sitting around, and the thing that broke was a thing you had a spare of. Did you have a spare controller? Did you have another motherboard/case that could accept this controller?

You just demonstrated how an inflexible solution can be somewhat mitigated by dint of effort and planning.

Planning is wise, but that doesn't change the fact that it's an inherently inflexible solution that's waiting for you to slip up to burn you.

If you didn't happen to have any spare scsi disks on hand, most people today would not be able to lay their hands on one in less than 24 to 48 hours no matter how much they're willing to pay for overnight, saturday delivery, special courriers etc. The only physically possible way to fix it immediately is to just already have the spares on-hand, not lost, not damaged.

Conversely, a flexible solution requires active effort and an extremely improbably amount of bad luck to concoct a situation that can't be addressed somehow. You could very easily discover that your one or few special spare drive or spare controller were damaged in that last office move, or by some water or other mis-handling that no one noticed until now because no one even knew what that forgotten thing at the back of that drawer was even for... but it's almost impossible that you can't put your hand on _some_, _any_, sort of hard drive or controller at any given time in any given place. Even in the middle of the night when stores are closed you could rob something from any desktop. Heck, you could even go down to the 24 hour grocery store and buy 10 16G usb thumb drives to replace a dead 146G scsi disk. I wouldn't run that way one minute longer than necessary of course, but your array would be optimal and you could actually lose another scsi disk while waiting for the proper disk to get shipped.

It's the difference between one possible way to deal with a situation vs infinite possible ways to deal with a situation.
No comparison. No contest.

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