add disks to existing RAID 5

July 26, 2005 at 13:36:46
Specs: Win 2003 Server, dual P4/1.5 Gig

I wish to add 2 disks to an existing RAID 5 hardware config. I dont want to build from scratch. I think I can add 2 drives an add them to the array. how do I do this? I have an adaptec RAID controller and 3 Cheetah 34 gig SCSI drives. I believe that if the disks can be added, then Paragon disk manager pro 6 will resise the partitions fine (even the system partition). I have tested this at home, my only questions are in implementing the new dries into the existing HARDWARE BASED Adaptec RAID 5. please contact me if you can be of any assistance, thank you!....

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July 26, 2005 at 17:21:22

it will be clear in the controllers cards documentation if it can do dynamic raid resizing. You don't mention the card but older cards don't have this option. You must wipe and reinit the array.

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July 26, 2005 at 17:22:24

you also don't mention the size of the drives you are adding. it makes a difference.

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July 26, 2005 at 21:14:52

Thanks Wanderer! The card is an Adaptec 2120S and is DOES indeed support expanding a RAID 5 array. I had to locate and download the "Adaptec Storage Manager" to communicate with the card. I'm going to move forward. the drives are all seagate cheetah 36 gig 68 pin 10,000rpm ST336607LW. I will be adding 2 additional drives, same make, model and size, adding up to 5 disks. My only remaining question is: does it make a difference which connector on the drive cable I use for each drive? I need a new cable, the old one has just 4 connectors. And then I will use Paragon Hard Disk Manager 6.0 Professional to allocate the new free space among my c:\ and e:\ drives....Thanks!!!

Ted Pethick

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July 27, 2005 at 07:49:44

You will not want to change position of the existing drives in the cable. Yes get a new cable.

Make sure you back up everything as there is a risk factor here.

Personally I never partition OS and data on a single raid5. SOP is to mirror the OS and raid 5 the data.

The reason for this standard operating procedure is just for what you are going to find yourself in shortly. It is rarely successful to add space to both the OS partition and the data partition. It is far better to wipe the data partition, add the drives, expand the OS partition into the raw area and then recreate the data partition and restore from backup.

You also get better performance if using a two channel card with OS on one channel and data on another.

The problem these partition managers have is moving the data so it can add space to the OS partition.

Its like you adding a bathroom in the center of the house while moving the rest of the house out of the way to provide the space for the bathroom.

I also highly recommend you add another drive as hot spare. If you have two drives fail you have lost everything. A hot spare should give you a margin of error in case of drive failure.

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July 27, 2005 at 14:37:55

Yes I agree with all your points. In addition, why they used 68 pin SCSI is a mystery to me (not hot-swappable)
unfortunately, budget will not allow all the improvements you have recommended. I do have a full windows backup, with an ASR set as well, just in case.
Have you used Paragon Disk Manager? I have tested the procedure on a Win2K3 server here at home, and have added space between system/data partitions several times. I have not tried claiming un-allocated space, however. What do you think?
what do you mean by "hot spare" you mean a 6th drive not in the array? managed by the RAID card software program?

Ted Pethick

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July 29, 2005 at 06:22:23

hot spare is an additional drive on the cable that is not part of the raid 5 array and is designated as a failover drive.

If you had data on the data partition [not just a partition with no data] and were able to add space to system/boot in a test with the product you should be fine.

Highly recommend you run chkdsk /f on the drives and defrag first. Increases the odds of success

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August 1, 2005 at 12:21:20

well, never got that far. after physically installing the 2 new drives, the boot 0.0 disk was immediately blown away, out of the RAID array. after this, the card could not initialize the 2 new disks, because it couldn't see them.
after 3 hours of rebuilding the array, I tried to install the new drives, while unplugging the 3 drive raid array. the 2010s still didnt see the disks. then I plugged all 5 in again, in different order, and once again the array was degraded, losing the 0.0 disk....what in god's name? hardware incompatibility?

Ted Pethick

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