-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 2015-07-09 15:39, Andrei Borzenkov wrote:
On Thu, Jul 9, 2015 at 12:22 PM, Carlos E. R.
Notice the «RAID 5 requires at least three disks.»
Personalities : [raid6] [raid5] [raid4] md0 : active raid5 loop1[2] loop0[0] 8704 blocks super 1.2 level 5, 512k chunk, algorithm 2 [2/2] [UU]
I have also seen statements that RAID5 must have exactly 5 disks.
In reality nothing in RAID5 *algorithm* prohibits or makes impossible having one data disk; it just makes no sense (it is more CPU intensive with zero advantages over RAID1 in this case). It is true that many implementations of hardware RAID won't allow you to create RAID5 with less than 3 disks, for the reasons I just mentioned.
Well... https://raid.wiki.kernel.org/index.php/Overview#RAID-5 « RAID-5 This is perhaps the most useful RAID mode when one wishes to combine a larger number of physical disks, and still maintain some redundancy. RAID-5 can be (usefully) used on three or more disks, with zero or more spare-disks. The resulting RAID-5 device size will be (N-1)*S, just like RAID-4. The big difference between RAID-5 and -4 is, that the parity information is distributed evenly among the participating drives, avoiding the bottleneck problem in RAID-4, and also getting more performance out of the disk when reading, as all drives will then be used. » That's the official information. - -- Cheers / Saludos, Carlos E. R. (from 13.1 x86_64 "Bottle" (Minas Tirith)) -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iF4EAREIAAYFAlWefN0ACgkQja8UbcUWM1y3uAEAgPqCsL13XDSgux2NRbxZTqjX JTm3ylg9EQx02+G0UT0BAJaCRv86loDdBI5nGPv9G7S3iiYBtQHRY2PxINhBRxYM =EE+P -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org