Software raid number of spares

Specifies the passphrase to use when encrypting this partition. You must use this option together with the --encrypted option; by itself it has no effect.

Specifies which type of encryption will be used if the Anaconda default aes-xts-plain64 is not satisfactory. Using either aes-xts-plain64 or aes-cbc-essiv:sha is strongly recommended. The keys are stored as a separate file for each encrypted volume. This option is only meaningful if --encrypted is specified. Add a randomly-generated passphrase to each encrypted partition. This option is only meaningful if --escrowcert is specified. It also creates three swap partitions, one on each drive.

Example A. For all other ONTAP disk types, you should have at least one matching or appropriate hot spare available for each kind of disk installed in your storage system. However, having two available hot spares for all disks provides the best protection against disk failure. Having at least two available hot spares provides the following benefits:. When you have two or more hot spares for a data disk, ONTAP can put that disk into the maintenance center if required.

ONTAP uses the maintenance center to test suspect disks and to take offline any disk that shows problems. Improve this question. RAID 5 uses one device's worth of parity. I don't know, which is why I'm making this a comment, but could that possibly have something to do with it?

In standard RAID terminology, a spare is just an inactive mostly blank disk that can be automatically spring into action to help rebuild the array after another disk fails. A parity disk is not a spare disk. Also, the number of spare disks is not the number of disks that can fail before your data is at risk. The number is not well defined. A four-disk RAID 10 could handle up to 2 disk failures, but it might also be dead with 2 disk failures. I'm guessing you're seeing two spares, because its still doing the initial array init—it is "rebuilding" on to one of the two spares.

Add a comment. Active Oldest Votes. Improve this answer. I think the key information from the wiki page you linked to is this: "For raid5 there is an optimisation: mdadm takes one of the disks and marks it as 'spare'; it then creates the array in degraded mode.

Apart from that, I'm afraid you misunderstood my question: I did not want to have 5 drives worth of space. Mentioning the 2 TB was just an observation. For the sake of clarity, I'll aggregate the information given by derobert and Alexandre Alves and some further testing of mine here: mdadm 's --spare-devices parameter does work as the man page states, i. Sign up or log in Sign up using Google.

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