EMC Symmetrix DMX-3, Product Manual

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196 EMC Symmetrix DMX-3 Product Guide
Data Integrity, Availability, and Protection
Symmetrix RAID 10 for mainframe systems
For Symmetrix, RAID 10 is used to designate the mainframe version
of RAID 1/0. For a mainframe environment, the implementation is
similar, except with a stripe size of one cylinder, and is implemented
in groups of eight drives.
In the past, this has also been referred to as “CKD Meta Volumes.”
Four Symmetrix devices (each one fourth the size of the original
mainframe device) appear as one mainframe device to the host. Any
four Symmetrix logical devices can be chosen to define a RAID 10
group provided they are the same type (for example, IBM 3390) and
have the same mirror configuration. Striping occurs across this group
of four devices with a striping unit of one cylinder, as shown in the
following figure. Each member of the stripe group is also mirrored,
thereby protecting the entire set. Dynamic Mirror Service Policy
(DMSP) can then be applied to the mirrored devices. The
combination of DMSP with mirrored striping and concatenation to
create a mainframe volume, as in
Figure 42 on page 196 , enables
greatly improved performance in mainframe systems. RAID 10 uses
four pairs of disks in its Symmetrix DMX implementation.
Figure 42
RAID 10 with Dynamic Mirror Service Policy
M1 M2
DMSP
SYM-000136