RAID confusion

[gadgetman]

I previously had a RAID 5 array of 4 x 500Gb drives. One volume was used for parity leaving 1.5Gb usable capacity.

Now I have just upgraded to 4 X 1TB drives yet when I created the volume is gave me a maximum volume size of 2TB. I expected it to be 3TB.

Anyone know what's going on?

[Liability]

Originally Posted by gadgetman

I previously had a RAID 5 array of 4 x 500Gb drives. One volume was used for parity leaving 1.5Gb usable capacity.

Now I have just upgraded to 4 X 1TB drives yet when I created the volume is gave me a maximum volume size of 2TB. I expected it to be 3TB.

Anyone know what's going on?

check the container to make sure it was created as a RAID5 set

[AtW]

Check OS limitation - I think it is 2 TB per NTFS partition in earlier version of Windows.

[gadgetman]

It looks like a problem/limitation with the RAID BIOS.

I deleted the volume and used the Intel Matrix app in XP to create it instead and it has given me the expected capacity.

The RAID BIOS however now does not recognize the volume. The Intel app insisted it needed to 'Initialize' the volume which it estimates will take 14 hours so hopefully all will be well when that completes.

[dmini]

NTFS isnt happy going above 2Tb as a volume. Beware
Yes there are ways round it with sector size etc, but don't touch it would be my advice

[gadgetman]

Don't like the sound of that...

I don't mind having multiple volumes but when I used the BIOS and it created the 2TB volume there was no additional space left with which to create another volume - I just seemed to be lose 1TB.

Am I stuffed here? Is 2TB a hard limit?

[TykeMerc]

It's quite possibly a limitation of an older RAID chipset. It may have been designed in the days when 2Tb was unbelievably large.

How old is your RAID adaptor?

[dmini]

A server can have far more than 2Tb of disk attached - its just that you can only have 2Tb in a single volume. Any restrictions beyond that point are unit based

[gadgetman]

About 18 months.

It uses the "Intel® ICH9R SATA RAID controller hub"

Originally Posted by TykeMerc

It's quite possibly a limitation of an older RAID chipset. It may have been designed in the days when 2Tb was unbelievably large.

How old is your RAID adaptor?

[gadgetman]

Unfortunately my adapter (at least in its BIOS setup) doesn't seem able to deal with 4TB. Anything above 2TB just seems to get lost.

I am using the latest BIOS by the way, I checked last night.

Maybe the Intel Raid software will allow me to create multiple volumes up to the total capacity. I will try this tonight.

Originally Posted by dmini

A server can have far more than 2Tb of disk attached - its just that you can only have 2Tb in a single volume. Any restrictions beyond that point are unit based