Raid Arrays - Buffalo TeraStation Setup Manual

RAID Arrays

TS-XL, TS-XEL and TS-RXL series TeraStations default to RAID 5 mode (4 hard drives), TS-WXL/R1 series default to RAID 1 mode, and
If you change the RAID
TS-WXL/1D series default to Normal mode. The characteristics of each type of RAID are described below.
mode, all of the data on the hard drive is deleted. Always back up any important data before changing the RAID mode.
Note:
In this document, "Recovery" means putting the TeraStation back to the state it was in before the malfunction happened. It does
not mean reading data from failed hard drives.
• RAID 5 mode (4 hard drives) (Default for TS-XL, TS-XEL and TS-RXL Series)
Note: TS-WXL/R1 and TS-WXL/1D TeraStations don't support this mode, as they don't have 4 hard drives.
Uses 4 hard drives as one array. It generates parity during writes, so access speeds are slower than other RAID modes.
Usable space is the sum of 3 hard drives' space. If one hard drive in the array is damaged, you can recover data by
replacing the hard drive. You cannot recover data if 2 or more drives are damaged.
• RAID 5 mode (3 hard drives)
Note: TS-WXL/R1 and TS-WXL/1D TeraStations don't support this mode, as they don't have 3 hard drives.
Uses 3 hard drives as one array. It generates parity during writes, so access speeds are slower than other RAID modes.
Usable space is the sum of 2 hard drives' space. You can designate a 4th drive as a hot spare, which will boot automatically
if one of the drives in the array fails. If one hard drive in the array is damaged, you can recover data by replacing the hard
drive. You cannot recover data if 2 or more drives are damaged.
• RAID 10 mode
Note: TS-WXL/R1 and TS-WXL/1D TeraStations don't support this mode, as they don't have 4 hard drives
RAID 10 combines 4 hard drives into a single array. Usable space is the sum of the capacity of 2 hard drives. Data is
written quickly and access speed is faster than other RAID modes except for RAID 0. Since the same data is written to 2
hard drives at the same time, if drive in a pair (1-2 or 3-4) is damaged, data can be recovered by replacing the damaged
hard drive. If both 1-2 or 3-4 hard drives are damaged, you cannot recover data.
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