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TechGuy_007Flag for United States of America

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changing drives on a RAID 5

we have a server running raid 5 and the drives have become to small and we need to replace them with larger drives.   i have been reading up on imaging raid 5 arrays and it doesnt look good.  

anyone have some advice on how to do this?

i have a PowerEdge T300 running server 03 sbs on a raid 5 array
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This is the perfect opportunity to also test a disaster recovery.  Use something like acronics and a large SATA HDD plugged into the motherboard's SATA adapter.  Image the LOGICAL device to that (norton or acronics can do this).  then see if you can boot up to the SATA disk as the new C drive after changing boot order in BIOS.    If that works, repeat the process so you have a clean copy.  At that point you are then free to plug in the larger HDDs, and build the new RAID array, and re-image the SATA disk to the new raid set.
You should be able to order an additional drive and expand the current RAID array without reinstalling. I would suggest calling Dell technical support to verify that your system and controller can do this. If it can they can also provide you with the correct part number.
Which PERC controller are you using?

Usually you can add new drives (assuming you have physical space) to the existing drives to give you more space.  But, expanding the size of the existing RAID logical drives using additional drives depends on the capabilities of the specific controller.  Older PERC controllers will let you do that, but they only use as much space on the new drives as exist on the current drives in the logical set.

If you are trying to do what I think you are, advice similar to what dlethe above gives is good, as removing all of your older smaller drives and replacing them with newer and larger drives will give you the best long term solution in terms of reliability, performance and size.  That means storing all of your data someplace else, and then putting it back.

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Kent Keller
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The PERC's do not support auto (or manual) expansion of the array, so replacing one disk at at time will not accomplish what you want.  You have two options:

1) Add a drive to the RAID 5 and convert your 3-disk RAID 5 to a 4, 5, or 6-disk RAID 5, then either simply extend the Data partition or use a partitioning software to resize you partitions, or

2) Image existing RAID 5, create new RAID 5, restore.
It really doesn't matter what RAID level your using with a Dell controller. if you want to use the full capacity of larger or newer drives you must recreate the array. Swapping drives into your existing array will not use the the additional capacity. However you could do this and then create another container using the remaining drive. But that's not what I think you would perfer. The best option is to image, via you favorite imaging tool. Then restore after you've added larger drives and reworked your RAID configuration. Just be sure to double check your shadow copy setting post restore. You'll typically lose your shadow copy data and have to reconfigure it.
As I said, and others said, getting a backup or image of the logical volume, and then rebuilding a new logical volume with larger physical drives, and then restoring the copy is your best bet.  It is tedious but gives you the best long range results.  Expansion of the existing volume to new drives will not give you all of the space, as the new driv4es are larger, but the PERC controller will treat them as the same size as the older (smaller) drives.
... unless he expands the RAID 5 by adding drives to it.  I'm not necessarily saying this is the best course of action, but if he is not fond of the idea of imaging/restoring, and five or six 73GB drives would give him enough disk space, this Reconfigure can be done while the server is online.
Just a note about justadad's answer that was accepted ...

"Some models of PERC would in theory let you install 1 larger drive in place of one of the smaller drives in the array ..."

No current models of the PERC support this, as the array cannot be safely expanded after such a rebuild.  Adding a drive to the current array by Reconfiguring the array is the only supported method of expansion of an array on any PERC you would find in a T300.
It would technically let you install it, certainly this would serve as a spare, but as the intention is to use this new space, then I agree with PowerEdgeTech -- it won't work.  The extra space won't be addressable.
I am assuming that he used the imaging tool that I mentioned and not the expanding of the array as the older model PERCs allowed.
Probably right ...  just didn't want those who come after to think that part of it would be a solution.