Hot spare operation, Hot spare drive protection – Dell POWERVAULT MD3620I User Manual

Page 133

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Configuration: Disk Groups and Virtual Disks

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Hot Spare Operation

When a physical disk fails, the virtual disk automatically rebuilds using an

available hot spare. When a replacement physical disk is installed, data from

the hot spare is copied back to the replacement physical disk. This function is

called copy back. By default, the RAID controller module automatically

configures the number and type of hot spares based on the number and

capacity of the physical disks in your system.
A hot spare may have the following states:

• Standby hot spare—is a physical disk that is assigned as a hot spare and is

available to take over for any failed physical disk.

• In-use hot spare—is a physical disk that is assigned as a hot spare and is

currently replacing a failed physical disk.

Hot Spare Drive Protection

You can use a hot spare physical disk for additional data protection from

physical disk failures that occur in a RAID level 1, or RAID level 5 disk group.

If the hot spare physical disk is available when a physical disk fails, the RAID

controller module uses redundancy data to reconstruct the data from the

failed physical disk to the hot spare physical disk. When you have physically

replaced the failed physical disk, a copyback operation occurs from the hot

spare physical disk to the replaced physical disk.
If there are secure disk groups and security capable disk groups in the storage

array, the hot spare physical disk must match the security capability of the

disk group. For example, a non-security capable physical disk cannot be used

as a hot spare for a secure disk group.

NOTE:

For a security capable disk group, security capable hot spare physical disks

are preferred. If security capable physical disks are not available, non-security

capable physical disks may be used as hot spare physical disks. To ensure that the

disk group is retained as security capable, the non-security capable hot spare

physical disk must be replaced with a security capable physical disk.

If you select a security capable physical disk as hot spare for a non-secure disk

group, a dialog box is displayed indicating that a security capable physical disk

is being used as a hot spare for a non-secure disk group.
The availability of enclosure loss protection for a disk group depends on the

location of the physical disks that comprise the disk group. The enclosure loss

protection may be lost because of a failed physical disk and location of the hot

book.book Page 133 Tuesday, June 18, 2013 3:09 PM

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