what RAID level requires a minimum of four disk drives to implement?

RAID 10, RAID 1+0 is striping mirrored disk sets. At the very least, you would need 4 drives to implement this. For example, you mirror disks 0 and 1 into segment Alpha, then you mirror disks 2 and 3 into segment Bravo, then you stripe across segments Alpha and Bravo.

Another option is to use RAID 0+1, this involves mirroring two striped sets. This could be done with just four disks as well.

RAID 0 and 1 require at least 2 disks

RAID 5 requires 3

RAID 10 requires at least 6

0 is simply putting data onto 2 disks at same time stripping it accross the 2. Great performance. No redundancy in a failure. No data gets saved.

1 is a mirror drive where the same data gets put onto 2 drives but look as one. If one drive fails data can be saved. Not great on performance.

5 is stripping with Parity. Basically there is 2 parts of every write sequence in which data is spread sebtween the 3 drives stripped like in a RAID0 but it also includes a parity bit. This extra bit on the drives when combined with the biots on the other surviving drive can create the third drive if it fails. Very good redundancy.

10 is a 5 array that is mirrored. So it requires 6 disks.

With all this being said, I know of no standard common RAID configuration that only requires a minimum of 4 disks. It is either 2, 3, or 6 as the bare minimums.

RAID 6 should require a minimum of 4 disk drives to implement. It's the same construct as RAID-5, but with dual parity drives.

RAID 5EE requires at least four disks!

RAID 5E, RAID 5EE and RAID 6E generally refer to variants of RAID 5 or RAID 6 with online (hot) spare drives, where the spare drives are an active part of the block rotation scheme. This allows the I/O to be spread across all drives, including the spare, thus reducing the I/O bandwidth per drive, allowing for higher performance. It does, however, mean that a spare drive cannot be shared among multiple arrays, which is occasionally desirable.

In RAID 5E, RAID 5EE and RAID 6E, there is no dedicated "spare drive", just like there is no dedicated "parity drive" in RAID 5 or RAID 6. Instead, the spare blocks are distributed across all the drives, so that in a 10-disk RAID 5E with one spare, each and every disk is 80% data, 10% parity, and 10% spare.The spare blocks in RAID 5E and RAID 6E are at end of array, while in RAID 5EE the spare blocks are integrated into the array.RAID 5EE level can sustain a single drive failure.RAID 5EE requires at least four disks and can expand up to 16 disks.

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Yeah I never heard of one that requires 4 disks.

Raid 5 require at least 3.

u can read about raid on

http://www.staff.uni-mainz.de/neuffer/scsi/what_is...