FUJITSU T5140 - Manual (Page 73)

Chapter 3 Managing Disk Volumes 51
Integrated stripe volumes provide for a logical unit (LUN) that is equal in capacity
to the sum of all its member disks. For example, a three-disk IS volume configured
on 72-gigabyte drives will have a capacity of 216 gigabytes.
FIGURE 3-1 Graphical Representation of Disk Striping
Caution – There is no data redundancy in an IS volume configuration. Thus, if a
single disk fails, the entire volume fails, and all data is lost. If an IS volume is
manually deleted, all data on the volume is lost.
IS volumes are likely to provide better performance than IM volumes or single disks.
Under certain workloads, particularly some write or mixed read-write workloads,
I/O operations complete faster because the I/O operations are being handled in a
round-robin fashion, with each sequential block being written to each member disk
in turn.
Integrated Mirror Volumes (RAID 1)
Disk mirroring (RAID 1) is a technique that uses data redundancy (two complete
copies of all data stored on two separate disks) to protect against loss of data due to
disk failure. One logical volume is duplicated on two separate disks.