Mailinglist Archive: opensuse (818 mails)

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Re: [opensuse] Recover Linux Raid 0 with 2x2port 3Ware Raid 1 cards
On 9/2/2011 2:38 AM, Per Jessen wrote:
Brian K. White wrote:

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,

If ordered before 17:00 and in stock, delivery usually follows the next
day with regular Priority Mail. (that's from a normal web-shop
available to everyone).
Regardless, a hardware array will typically be configured with 1 spare
drive sitting idle, so you'd be replacing the failed drive a while
after your array had already recovered. No need to hurry at all.

A day is an eternity.

A hot spare is both aging at the same rate as all the active drives, and is still as I said planning overcoming the limitations of the system, not a system that lacks the limitation in the first place.

There is no getting around that simple math.

Very often, if everyone did everything they were supposed to, it's good enough. Counting on, depending on, requiring, everyone, or even just yourself, always doing what they're supposed to is less than wise.

And even when they do it doesn't fix the inherent limitations.

A few months ago one of the hosting facilities where I have a rack of servers had a power issue which killed half of the sata ports in some of my machines. It's not clear from remote whether it's the backplanes or on the controller cards that are fried. But it is clear from having the on-site staff move drives around to different hot swap bays that the drives themselves weren't actually hurt at all.
Spare drives, be they in the array as hot spares or on the shelf, wouldn't have helped at all. Not being tied to any special hardware helped. The array itself, as in the drives and the data on the drives, was actually still fine. They could all be moved to a neighboring machine that had different hardware and run.

Now go ahead and say "You're supposed to use ups's to avoid having power issues."

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