Linux RAID 5 Redundancy

I have 3 1TB drives in a software program RAID - 5 arrangement with LVM working on top of it. Each drive is separated right into 2 500GB dividings. So regarding mdadm recognizes, it has 6 tools.

Presently the raid array has 2.5 TB of room ; I'm thinking among the 500GB dividings is being made use of for parity? Or possibly 500GB is being made use of throughout the array, I'm not specifically certain.

My inquiry is: with this arrangement, am I secure if any kind of among the drives fall short? Or, do I require to add a 4th drive with an additional 500GB dividing as an extra? Or do I require to add an additional 500GB dividing from a 4th drive and also in some way define it to be made use of for parity?

2019-05-18 20:48:39
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Answers: 1

No, you are not secure.

The suggestion with RAID 5 is to have N+1 disks (giving complete storage matching to N disks), with adequate redundancy to recoup if one disk falls short. (The parity is in fact dispersed over all the disks with RAID 5.)

Nonetheless, by separating each of your 3 physical disks right into 2 dividings, you've set up 5+1_500GB dividings (giving 5 *500 GB room), with defense if one dividing falls short. Nonetheless if one drive falls short entirely, you will certainly shed the 2 dividings that get on it, and also you do not have adequate redundancy to recoup from that.

The common method with RAID 5 is to leave your physical tools unpartitioned (or with just one dividing each), create the RAID array, and afterwards dividing the resulting tool if essential.

Also if you add an additional 500 GB dividing, you still will not be secure if you still make use of RAID 5, due to the fact that the added dividing will not add even more redundancy, just extra ability. You would certainly need to switch over to something like RAID 6, which gives defense versus shedding 2 drives.

2019-05-21 03:41:53