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

SFS20 storage — overview and planning 5–23
• There must be two MDS LUNs for each file system, one on each of two arrays attached to the MDS
and administration server. This configuration is required to support mirrored LUNs.
• You can configure the SFS20 arrays with either ADG or RAID5 redundancy (see Section 5.3.3 for
more information).
• The best performance is obtained from a single disk group populated with as many disks as possible.
The default disk group size is eleven disks.
Two disk sizes are used in SFS20 arrays attached to the administration and MDS servers: 160GB and
250GB.
• If 160GB disks are used, the maximum number of disks that can be in a disk group is eleven
(plus one spare disk for use in case of disk failure).
• If 250GB disks are used with ADG redundancy (the default), a disk group can contain a
maximum of eleven disks. However, if RAID5 redundancy is used, the maximum number of disks
that can be in a disk group is ten, plus up to two spare disks for use in case of disk failure.
See Section 5.5 for information on sizing the MDS LUNs.
Example 1 — One file system
The following is an example of configuring the storage on arrays attached to the administration and MDS
servers in a system where there will be one file system.
The command is entered with the default options, as follows (arrays 1 and 2 are attached to the
administration and MDS servers):
sfs> configure array 1,2
This command configures each array as follows:
• One disk group of eleven disks, plus one spare disk
• ADG redundancy
• An administration LUN (or spare administration LUN)
• A service LUN (or spare service LUN)
• One MDS LUN using all of the remaining available space in the disk group
Table 5-5 shows details of the resulting configuration on the two arrays attached to administration server
and the MDS server (south1 and south2). For more information on the configure array command,
see Section 7.7.2.
Table 5-5 SFS20 arrays attached to the administration and MDS servers — one file system
Array Disk Group Size Role Connected to Notes
1 140GB
1
adm south[1-2] The administration LUN.
11GB service south[1-2] The service LUN for the south1
and south2 server pair.
1 All of the
remaining
capacity in the
disk group to a
maximum of 2TB.
mds south[1-2] An MDS LUN. See Section 5.5 for
information on sizing the MDS LUN.