Subsystem Device Driver For Open-Systems; Balancing The I/O Load; Storage Consolidation - IBM TotalStorage DS6000 Introduction And Planning Manual

Concurrent Copy
Concurrent Copy is an optional function that is available with the z/OS remote
mirror and copy feature and is supported on the DS6000 series.
DS6000 storage complexes support the Concurrent Copy feature on zSeries hosts.
Concurrent Copy, like FlashCopy, creates point-in-time copies of volumes. However,
Concurrent Copy can also copy data sets from a source volume. It can copy the
data to tape, to an optical library, or to another storage device. Data systems like
the IBM DB2

Subsystem Device Driver for open-systems

The IBM TotalStorage Multi-path Subsystem Device Driver (SDD) supports
open-systems hosts.
The Subsystem Device Driver (SDD) resides in the host server with the native disk
device driver for the storage unit. It uses redundant connections between the host
server and disk storage in the DS6000 series to provide enhanced performance and
data availability.

Balancing the I/O load

You can generally maximize the performance of an application by spreading the I/O
load across clusters, arrays, and device adapters in the storage unit.
During an attempt to balance the load within the storage unit, placement of
application data is the determining factor. The following resources are the most
important to balance, roughly in order of importance:
v Activity to the RAID disk groups. Use as many RAID disk groups as possible for
v Activity to the clusters. When selecting RAID disk groups for a critical application,
v Activity to the device adapters. When selecting RAID disk groups within a cluster
v Activity to fibre-channel or FICON ports. Use the IBM TotalStorage Multipath

Storage consolidation

When you use a storage unit, you can consolidate data and workloads from
different kinds of independent servers into a single shared resource.
You might mix production and test servers in an open systems environment or mix
S/390 or zSeries and open systems hosts. In this kind of independent server
environment, servers rarely, if ever, contend for the same resource.
®
product can also initiate Concurrent Copy.
the critical applications. Most performance bottlenecks occur because a few disks
are overloaded. Spreading an application across multiple RAID disk groups
ensures that as many disk drives as possible are available. This is extremely
important for open-system environments where cache-hit ratios are usually low.
spread them across separate clusters. Because each cluster has separate
memory buses and cache memory, this maximizes the use of those resources.
for a critical application, spread them across separate device adapters.
Subsystem Device Driver (SDD) or similar software for other platforms to balance
I/O activity across fibre-channel ports.
Note: For information about SDD, see IBM TotalStorage Multipath Subsystem
Device Driver User's Guide. This document also describes the product
engineering tool, the ESSUTIL tool, which is supported in the pcmpath
commands and the datapath commands.
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Chapter 1. Introduction