HP StorageWorks Scalable File Share System Installation and Upgrade Guide Version 2.2

Preparing for the installation2–28
Configurations (b) and (d) each have eight OST services. However, configuration (b) has fewer servers, and
this may lead to lower performance. The administration and MDS services may also have a performance
impact—this is determined by the access patterns of the file systems
2.9 Assigning storage arrays to servers
NOTE: The tasks associated with storage planning and configuration are described in Chapter 5
(EVA4000 and SFS20 storage) and Chapter 7 (SFS20 storage only).
NOTE: Use the worksheets in Table B-8, Table B-9 (one copy of this worksheet for each EVA4000 array),
and Table B-10 (one copy of this worksheet for each SFS20 array) in Appendix B as you plan and
configure your storage. You can record the details of your storage configuration, including a mapping of
the LUNs that will be on each array, and the arrays that will be connected to each storage pair.
You must plan to assign the storage arrays to the servers. When planning your array assignments, note the
following points:
• You cannot mix the storage types within an HP SFS system.
• A system configured with EVA4000 or SFS20 arrays is configured to have high availability. This
means that servers are grouped in server pairs. Normally, the storage on an array is accessed by one
server. However, if a server fails, the second server in the server pair has the ability to access the
array normally accessed by the first server. This means that the arrays and servers must be physically
configured in such a way that both servers can access both of the arrays. In effect, the arrays are also
grouped in pairs.
• If EVA4000 storage is used, and no OST services are run on the administration and MDS server pair
(such as in configurations (c) and (d) in Table 2-10), these servers may be configured with one
dedicated EVA4000 array.
• The administration and MDS server pair must always have at least one EVA4000 array or two SFS20
arrays assigned to it.
• Each pair of servers that run OST services must have at least two EVA4000 or two SFS20 arrays
assigned to it.
• When SFS20 storage is used, the administration and MDS server pair can be configured with a
maximum of four SFS20 arrays, while each Object Storage Server pair can be configured with a
maximum of eight arrays.
• With EVA4000 arrays, when you have determined which arrays are grouped with each of the server
pairs, selective presentation is used during installation to control the visibility of logical unit numbers
(LUNs) to the server’s Fibre Channel Host Bus Adapter (HBA) ports. This functionality is described in
Chapter 5. Ensure that the arrays that are grouped with a server pair are on the same Fibre Channel
switch(es) as the server pair.
• SFS20 arrays are connected directly to the servers, and only the connected arrays are visible to the
servers.