Dell PowerVault LTO2-110T Manual Del Usuario página 10

RAID 1
Also known as mirroring, RAID 1 means data is written twice across two disks simultaneously. If
one drive fails, the system switches to the other drive without losing data. During tape drive
backups, the read rate from the RAID 1 array is approximately the same as a single drive because it
is reading from the primary drive. However, restore performance from the tape drive writing to the
RAID 1 array can be slower due to error checking/correction (ECC) included in writing to the
primary and mirrored disks. Much of this inefficiency is due to the fact that the mirroring is often
performed on the CPU or RAID controller. Thus, newer RAID controllers tend to be faster due to
newer and more capable processors.
Figure 1-3. Example RAID 1 Configuration
10
Performance Considerations for Tape Drives and Libraries
Hard Drive 1 Hard Drive 2
D = Data Byte
D1
M = Mirrored Byte
D2
D3
D4
D5
Read/Write
SCSI or RAID
Read/Write
M1
M2
M3
M4
M5
Write Only
Controller
Tape Drive