Help, my disk array has one dead member

[Remi Gauvin]

On 17-03-27 01:16 PM, Kevin O'Gorman wrote:

> Fortunately, I think RAID5 is a good fit for my use-case.  Overall,
> it's compute-intensive, not so much DB-intensive.  My requirement of
> the database is that it be large and reliable, not so much fast.  I
> tend to be working on a small part of the data at a time.  I have
> compute tasks that run for days with no disk activity at all.

The problem with Raid 5 is not performance, (which I think is kind of 
great,,, CPU's have long since gone past the point where parity 
calculation was an issue.)

It's reliability.  Generally, there are all kinds of common failures 
that can temporarily take out 2 drives, (example, say, one of your 
Controller's that has 2 drives attached fails or just locks up somehow.)

the result will be the kernel marking your array as damaged and dead. 
You can force the array to rebuild, but with the huge size of modern 
drives, having to way over 24 hours see if you succeed can be stressful.

So don't temp Murphy, if using Raid-5, make sure you have good up to 
date backup at all times.

If you need a system that can be recovered from failure the fastest, 
stick with Raid-1


(Having written all that, I use Raid-5 for my own storage needs.. I'm 
not against it by any means.)


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