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Re: Disk performance deteriated to unbearable levels

Bob Proulx wrote:
For your next system I highly recommend setting it up with RAID. It makes problems like these so much easier. [Of course because of the problem with flooding in Thailand and human reaction to it the cost of disk drives is soaring right now. Unfortunate timing to lose a drive.]

Something to keep in mind if you go with RAID:

- Conventional "desktop" drives make best efforts to read data off the media. As the "raw read error" rate goes up, the drive spends more and more time trying to re-read the media, often succeeding, right up to the point of catastrophic failure. On the one hand, this is a good thing - you're more likely to recover your data. On the other hand, it's horrible, in that:
----- you start seeing response times slow to a crawl (as in the case here)
----- if the drive is part of a RAID array, the entire array will slow to a crawl (at least with linux software RAID, md will not drop a slow drive out of the array)

- What you want is an "enterprise drive" that gives up very quickly if it can't read the media. That way, the drive will return a read error the the RAID driver (or hardware), the drive will be dropped from the array, and the array will read your data from another drive. Hopefully you'll also get notified that the drive has failed, so you can replace it.


In theory, there is no difference between theory and practice.
In<fnord>  practice, there is.   .... Yogi Berra

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