Designating Hot Spares in a Storage Pool

Devices can be designated as hot spares in the following ways:

• When the pool is created.

  $ zpool create pool keyword devices spare devices

• After the pool is created.

  $ zpool add pool spare devices

To remove a hot spare, use the following command:

$ zpool remove pool spare-device

Note:

You cannot remove a hot spare that is currently being used by the pool.

A hot spare device must be equal to or larger than the size of the largest disk in the pool. Otherwise, the smaller spare device can still be designated as a hot spare. However, when that device is activated to replace a failed device, the operation fails with the following error message:

cannot replace disk3 with disk4: device is too small

Do not share a spare across multiple pools or multiple systems even if the device is visible for access by these systems. You can configure a disk to be shared among several pools provided that only a single system must control all of these pools. However, this practice is risky. For example, if pool A that is using the shared spare is exported, pool B could unknowingly use the spare while pool A is exported. When pool A is imported, data corruption could occur because both pools are using the same disk.