On Thu, Jul 9, 2015 at 12:22 PM, Carlos E. R.
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On 2015-07-09 05:17, Andrei Borzenkov wrote:
В Wed, 08 Jul 2015 23:37:28 +0200 "Carlos E. R." <> пишет:
A two disk raid 5 is "degraded", and it will complain till you complete it.
Where have you go this idea?
Several sources. For instance:
https://en.wikipedia.org/wiki/RAID#Standard_levels
«RAID 5 RAID 5 consists of block-level striping with distributed parity. Unlike in RAID 4, parity information is distributed among the drives. It requires that all drives but one be present to operate. Upon failure of a single drive, subsequent reads can be calculated from the distributed parity such that no data is lost. RAID 5 requires at least three disks.[11] RAID 5 is seriously affected by the general trends regarding array rebuild time and the chance of drive failure during rebuild.[22] Rebuilding an array requires reading all data from all disks, opening a chance for a second drive failure and the loss of entire array. In August 2012, Dell posted an advisory against the use of RAID 5 in any configuration on Dell EqualLogic arrays and RAID 50 with "Class 2 7200 RPM drives of 1 TB and higher capacity" for business-critical data.[23]»
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. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org