HP StorageWorks XP Remote Web Console Software - Manual (Page 49)

External Storage XP user guide 49
5. Click OK in response to the warning message.
6. Click OK.
7. Remap the LU using all the previous settings except for the cache mode setting, which is disabled. See
” Mapping external LUs (Add LU) ” on page 73.
NOTE: When scanning for devices to add, the order in which devices are discovered might be
different. The UUID is always the same for the same external device. Ensure that the UUID of the
device being remapped matches the UUID that was deleted for the same LU number.
8. Recheck to ensure that the same external storage LUs (identified by UUIDs) are now assigned their
original settings and the desired cache mode. If not, delete and remap the external LU again.
Partitioning cache for external storage
Separate cache partitions isolate the applications that are using XP arrays and storage virtualization
systems from the I/O dampening effects of a cache that is filling up with host and internal I/O for slower
external targets. HP requires separate cache partitions (CLPRs) for:
• External volumes and internal XP volumes, except for configurations where all external storage LUNs
have cache disabled and do not have any external storage devices using data mirroring or migration
products
NOTE: All HP 200 Storage Virtualization System volumes are external. Partition SVS200 cache
according to the other recommendations made in this section.
• External volumes that are used by XP data replication or data migration products, including Business
Copy XP, Continuous Access XP software products, Snapshot XP, Auto LUN XP, and XP Tiered Storage
Manager
• SVS200 source volumes and data copy or target volumes that have slower throughput
For example, Company A uses:
• XP10000 internal disks for database applications
• EVA3000 for backup applications
Cache can be partitioned for Company A as follows:
• CLPR0: XP10000 for Business Copy XP P-VOL
• CLPR1: EVA3000 for Business Copy XP S0VOL (external LU cache is disabled)
In another example, Company B uses the following storage tiers:
• Tier 1 is an XP12000 (6 TB of internal space) for P-VOLs
• Tier 2 is an EVA (20 TB) for P-VOLs and Business Copy XP S-VOLs
• Tier 3 is two MSA 1500 (10 TB) for the Business Copy XP S-VOLs
Cache can be partitioned for Company B as follows:
• CLPR0: 12 GB for the internal XP12000 P-VOL
• CLPR1: 4 GB for the EVA S-VOL and P-VOL
• CLPR2: 4 GB for the MSA S-VOL
• All external LU cache is disabled.
To partition cache for external storage:
1. Determine the number and size of the partitions you need (see page 50).
2. Create the partitions (see page 50).