Buffalo TeraStation III TS-IXL, Руководство пользователя

Страница: 18 / 65

TeraStation III iSCSI User Manual 17
Chapter 5
Changing RAID Modes
• RAID 5 mode (4 hard drives) (factory default)
Uses 4 hard drives in one array. Parity information for correcting errors is stored, so access speeds are slower than other
RAID modes. Total usable space is the sum of the capacity of 3 drives. If a drive is damaged, you can recover data on the
array by replacing the damaged drive. You cannot recover data if 2 or more drives are damaged.
• RAID 5 mode (3 hard drives)
Uses 3 hard drives in one array. Parity information for correcting errors is stored, so access speeds are slower than other
RAID modes. Total usable space is the sum of the capacity of 2 hard drives. The fourth disk may be used as a hot spare,
which replaces a failed drive automatically. If a drive is damaged, you can recover data on the array by replacing the
damaged drive. You cannot recover data if 2 or more drives are damaged.
• RAID 10 mode
Uses 4 hard drives in one array. The space you can use is the sum of 2 hard disks' space. Data will be written speeded
and this makes access speed slightly faster. Since same data are written in the 2 hard disks at a same time, even though
one of the paired hard disks (1-2 or 3-4) is damaged, data can be recovered by replacing the damaged hard disk (if both
1-2 or 3-4 hard disks are damaged, you cannot recover data).
• RAID 1 mode
Uses 2 hard drives in a mirrored array. You can create up to 2 RAID 1 arrays. Total usable space on a RAID 1 array is the
capacity of one of the drives. If either drive is damaged, data can be recovered by replacing the damaged drive. You
cannot recover data if both drives are damaged. The other two drives not used in the RAID 1 array may be used as hot
spares which replace failed drives automatically, or as a second RAID 1 array, or as individual drives. Or, one may be
configured as an individual drive and the other as a hot spare.
Note:
After replacing a failed drive in any of the above arrays, file transfer speeds will be slower for several hours while the RAID
array is being rebuilt. During this period, the front LED display will show “RAID ARRAYx Resyncing”.
Out of the box, your TeraStation is configured with all four hard drives in a RAID 5 array. Many other RAID array modes
are available.
Notes:
• All data on your drive will be deleted if you change the RAID mode. Back up any important data before changing RAID
modes.
• In this document, “Recovery” means restoring the TeraStation back to the state it was in before the mulfunction
happened. It does not mean reading data from failed hard drives.