Hi Nobody, I answered part of your question on the other thread, hopefully some of this will be useful.
The problem: You have a hard drive enclosure with 5x 1TB drives. You want to make the largest possible single drive that the operating system can use while still offering RAID protection. However, your 32 bit O/S can only see a max 2TB drive.
RAID is a compromise, it always sacrifices drive capacity for redundancy. The higher the RAID number, generally the better the protection. The exception is RAID0 - ie. zero protection but higher performance due to reading from many drives at once.
You will have to “log on” to the management screen of the drive enclosure and experiment with the available configurations to see how best to divide up the hard drives.
RAID0: Not really an option as there is no extra data security but you could use 2x 1TB (2TB total) / 2x 1TB (2TB total) and 1x 1TB (1TB total) giving you three separate non-redundant drives to use. Data is broken up into chunks and “stripe” written to the drives in turn giving performance but no extra protection.
RAID1: Disk mirroring, but you lose 50% of the available drives per array. So you could set up 2x 1TB (1TB total) / 2x 1TB (1TB total) and 1x 1TB unassigned. You end up with 2 usable drives but have “lost” three out of the set due to redundancy ie. drives without a pair. You could also have a pair of drives mirrored, ie. (2x 2x 1TB) and 1 drive spare but you would still only have a single 2TB drive to play with. Gives good redundancy but at a high price in lost overall capacity.
RAID5: Best compromise, data is broken up into chunks and an extra parity chunk is created based on the original data. It is then stripe written to the drives in turn giving both performance and redundancy. You need at least 3 drives to make this work so you could use 3x 1TB (2TB total) and mirror the remaining 2x 1TB (1TB total) giving you two drives, one striped of 2GB and one mirrored of 1 TB.
Other RAID levels play about with striping a mirror etc and can be demanding of overhead - check Wikipedia article - eg. RAID6 can tolerate two drives failing at once where RAID5 can only tolerate one failure.
Having said all this, the best thing to do would be to see if the management software allows you to create “logical” splits. To explain, you create a RAID5 set including all 5 drives - this gives you a physical array of 4TB. But - you then say: I want to make a logical division of that array into two “software” or “logical” drives of 2TB each.
So the underlying hardware is a 5-disk RAID5 array, but two 2TB logical drives are passed to the operating system for use. Driver abstraction means the O/S won’t even know it doesn’t have two distinct drives.
That’s the best way to go ending up with 2x 2TB protected drives but if that is not possible go with one stripe and one mirror giving 1x 2TB and 1x 1TB.