2.4.10 Disk Mirroring; Example Of Disk Mirroring (Raid 1) - Lenovo ThinkServer RD240 Software User's Manual

2.4.9.1 Stripe Width
2.4.9.2 Stripe Size
2.4.9.3 Strip Size

2.4.10 Disk Mirroring

2-8
Stripe width is the number of drives involved in a drive group where
striping is implemented. For example, a four-disk drive group with disk
striping has a stripe width of four.
The stripe size is the length of the interleaved data segments that the
RAID controller writes across multiple drives, not including parity drives.
For example, consider a stripe that contains 64 KB of disk space and has
16 KB of data residing on each disk in the stripe. In this case, the stripe
size is 64 KB and the strip size is 16 KB.
The strip size is the portion of a stripe that resides on a single drive.
With mirroring (used in RAID 1 and RAID 10), data written to one drive
is simultaneously written to another drive. The primary advantage of disk
mirroring is that it provides 100 percent data redundancy. Because the
contents of the disk are completely written to a second disk, data is not
lost if one disk fails. In addition, both drives contain the same data at all
times, so either disk can act as the operational disk. If one disk fails, the
contents of the other disk can be used to run the system and reconstruct
the failed disk.
Disk mirroring provides 100 percent redundancy, but is expensive
because each drive in the system must be duplicated.
an example of disk mirroring.
Figure 2.2

Example of Disk Mirroring (RAID 1)

Segment 1
Segment 2
Segment 3
Segment 4
Introduction to RAID
Segment 1 Duplicated
Segment 2 Duplicated
Segment 3 Duplicated
Segment 4 Duplicated
Figure 2.2 shows