Isl Ratio; Incremental San Expansion; San Configuration - HP StorageWorks 4000/6000/8000 - Enterprise Virtual Arrays Reference Manual

Distributed (many-to-many)—Data access between multiple, dispersed servers and storage systems
See Table 3 on page 46 for recommended topologies based in the primary data access type.

ISL ratio

Determine the ISL ratio for switch-to-switch connectivity based on the workload of servers and storage
systems. In some cases, you can assess the I/O requirements of your applications and servers by
using application sizing tools. After deployment, use current system measurements to determine the
actual workload, and modify your implementation if the initial design does not meet your requirements.
See Recommended ISL ratios

Incremental SAN expansion

Plan for expansion when the initial design is a subset of a future, larger design. For example, if you
are using a core-edge topology in the initial design, allocate spare ports on the core switches to
support addition of edge switches.
To expand the SAN, you can make incremental changes rather than reconfiguring the entire SAN.
Changes to the core switches are isolated from the edge switches, which minimizes the effect of
changes required to support core growth. Changes to the server connection to an edge switch are
isolated from the core, which minimizes the effect of server-related changes. If you are using two or
more fabrics, you can temporarily route server I/O traffic to one fabric while the other fabric is being
modified.

SAN configuration

After completing the planning phase, you can configure your SAN. During the configuration phase,
record details about the physical configuration.
To facilitate maintenance, observe the following practices:
Record keeping
Record the cable connections on the configuration layout diagram. Record the WWN and location
of each node and device.
HBA labels
Affix a label on each HBA that clearly identifies the WWN. HP storage systems are prelabeled
with this information. Affix another label in plain view if necessary.
Cable labels
Label both ends of each cable with a cable number or color-coding scheme. This allows you to
quickly identify each cable. Securely affix a label to each end of the cable to identify connection
points, such as TO and FROM.
Switch ports
Use port plugs to protect unused switch ports; never leave ports exposed.
Cable dressing
Use care when routing fiber optic cable and ensure that cables conform to the minimum bend ra-
dius requirements (see
group and support the cables.
on page 44 for more information.
Table 71 on page 168). Use hook-and-loop (Velcro brand) tie wraps to
SAN Design Reference Guide 419