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I was told by an HP support guy that I should not replace a failed drive in a mirror with a bigger size drive, since it could crash my array.

I am puzzled why is this so and how to hell am I suppose to support this array once the specific hdd model is not available any more?

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I never quite understood the arguement against different sized disks, different speeds I can understand if striping accross disks is going on. Maybe someone will enlighten us. –  ITGuy24 Apr 15 '10 at 15:56
    
That last question should be asked of the HP support guy ... –  tomjedrz Apr 15 '10 at 17:22

4 Answers 4

up vote 5 down vote accepted

There's a big difference between "It should work" and "It will work" and if I was that HP guy I'd have gone with the first statement too, if he'd gone with the second and you'd lost data he could have been in trouble. That said 'it should work' :)

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Excellent point .. +1. One would hope that the RAID controller software can handle the different drives and use the lowest common denominator, but different drive sizes brings all kinds of edge conditions and exceptions that will increase the risk. I wouldn't count on it for production data! –  tomjedrz Apr 15 '10 at 17:21

Unless there's some specific bug in the hardware, all putting a larger drive in the array will do is make the space beyond the size of the smaller drive unused/unusable.

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OEMs almost never recommend putting different sizes or speeds in an array together. But you can definately do it, unless as already stated the OEM has a bug or "feature" that prevents it.

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@Jacka: What kind of setup is this---a custom-built PC, an OEM PC, or a server? It sounds like an OEM.

As a matter of curiosity: Even if you can't find the same exact model, can you find a drive with the same capacity?

@ITGuy24: Nitpick(?) on your comment up top---this is a RAID 1 or mirrored array.


I concur. If you use a larger drive in a generic array (i.e. not using specialized software like MirrorFolder or FlexRAID), you shouldn't have a problem, but: (1) you do lose the extra capacity, and (2) the other drives generally have to "wait" in some way for a lower-performance drive. Note that equal RPMs does not mean equal performance. Cache size plays a huge role, and access times perhaps a slight one.

(Sorry, could only post one link, but FlexRAID is easy to find.)

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It's a HP 370 server with HP SmartArray 410i controller –  jacka Apr 15 '10 at 18:21
    
And what kind of drive are you using? –  Mark C Apr 22 '10 at 13:35

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