RAID (SCSI) Reconfiguration.  4 36GB in RAID, 1 76GB outside of RAID - Options?

Posted on 2005-04-19
Last Modified: 2010-04-03

First let me appologize for my lack of knowledge on RAID Systems.  I know enough to get by, as I have had to take over our small server as part of downsizing (not part of my normal daily routine).

The problem we are facing is inadequate storage.  We have a Dell System that has 5 slots for Hot-Swapable SCSI drives which contain 4 36GB drives in a RAID and the 5th slot contains a 76GB drive for backups.  The 4 drives are then partioned off approximately 10GB for the OS, and 60GB for the Storage (D Drive).  I am exploring upgrade options, one of which would utilize what we have with no additional purchase.  After talking to DELL support, i realize a few options i have, but wanted to run this by someone not at Dell.

According to the DELL rep, if i were to introduce a larger hard-drive into the RAID system, only 36GB would be used.  (and even if all 4 were switched, it would still use 36GB unless i redid the RAID setup).  However, he said that the space not used for RAID, could be used for storage.

If i were to (is it possible) introduce the 76GB drive into the RAID (all 5 drives used), i am assuming this would provide the overall RAID with an additional 36GB, which would equate to 18GB additional usable space?  Leaving 36GB Non-RAID for other storage?  Which partiton would get the additional space?--Is this something configured upon introducing the new drive to the RAID?

Another option i have is to replace the 4 drives with bigger drives, leaving the 36's unused unless i buy a "PowerVault" -- Dell charges about $2,500 just for this vault, which is high for our company/situation.  Any other options / hardware that can be setup to use these drives?

Thank you for your time.

Question by:hbtitansfan
    1 Comment
    LVL 3

    Accepted Solution

    Your correct ..
    According to the limitations of your hardware you could logically expand the RAID set to the fifth disk. This would be like adding another disk to the set. With few exceptions, all RAID arrays are constrained by the size of the smallest drive(s) in the array--any drives larger than this will not utilize their additional capacity. The additional space could be used in a new partition.

    Or you could buy larger disk(s), insert them into the RAID set and allow your information to rebuild on them one at a time. You will end up with a RAID set of the same size as the original disk and additional unpartitioned space on that disk which could be used to set up an additional partition. The additional space on all your disks could be used to create an additional larger and seperate array. You could move your data to the larger array and use the old array as backup.

    I ran into the same problem on my proliant email server. I had to exchange the existing 36GB drives with 146GB drives and move my exchange store to a new partition/array which I created from the additional unused space that was provided by the new drives.

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