Mirroring and Duplexing

You can protect the data mirroring or duplexing disk partitions.

Mirroring stores the same data on separate disks on the same controller channel; duplexing stores the same data on separate disks on separate controller channels. Duplexing can also use two different drivers. Duplexing is the recommended method because two channels rarely fail simultaneously.

In the following illustration, several smaller disks are mirrored to partitions on one larger disk.


Mirroring small disks to partitions on one large disk

To mirror partitions you must enable Hot Fix. For information about Hot Fix, see Redirecting Bad Blocks .

With Hot Fix enabled, a section of the partition is set aside as the Hot Fix/Mirror object, which holds data tables for both Hot Fix and mirroring. The tables store information about which data blocks are bad, which blocks have been redirected, which partitions are mirrored, and whether the partitions are synchronized or not.

Setting up Hot Fix is much easier when you create the partition. To add Hot Fix after you create a partition and add volumes, you must delete the volumes from the partition, add Hot Fix, then restore the volumes from a backup. When you restore volumes from a backup, make sure you have enough space on the partition to accommodate the volumes after you add Hot Fix to the data area.

The following are important concepts for mirroring partitions:

For information about how to set up mirroring and duplexing, see Mirroring and Duplexing Partitions .