HP StorageWorks Cache LUN XP user guide for the XP1024/XP128 Part number: T1616-96002 Second edition: March 2006
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Contents About this guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Intended audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Prerequisites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Firmware versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Related documentation . . . . . . . . . . . . . .
About this guide This guide provides information about the following: • ”Supported volumes” on page 9 • ”Cache LUN XP tasks” on page 9 • ”Supported emulation types and other parameters” on page 9 • ”Restrictions” on page 10 • ”Cache LUN XP modes” on page 10 • ”Pre-staging” on page 11 • ”Starting Cache LUN XP” on page 12 • ”Setting (creating) a cache extent” on page 14 Intended audience This guide is intended for customers and HP-authorized service providers with knowledge of the following: • Disk array har
Document conventions and symbols Document conventions Table 2 Convention Element Blue text: Table 1 Cross-reference links and e-mail addresses Blue, underlined text: (http://www.hp.
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1 Cache LUN XP for the XP1024/XP128 Use Cache LUN XP to reserve areas of cache memory on the disk array for storing high-use data from the LDEVs. Data access speed is improved because the cache-resident data is available to the hosts at much faster transfer speeds. This can be applied to both read and write I/O operations. Supported volumes Cache LUN XP works with normal volumes, LUSE volumes, and custom volumes (configured through CVS).
Unit of cache area allocation A Cache LUN XP extent is a range of logical blocks within an LDEV. A logical block is 512 bytes. For OPEN-V, a cache extent must have at least 128 Logical Block Addresses (LBAs), or 66 KB. For all other supported open system emulation types, a cache extent must have at least 96 LBAs, or 49.5 KB. This is known as a cache slot. A cache extent can have a maximum size of an entire LDEV, up to the limits of Cache LUN XP cache memory.
• While destaging to disk, read requests to the same block are delayed until the disk operation is completed. • Priority mode generates write traffic to disk, whereas bind mode does not. General cache capacity In addition to the Cache LUN XP cache, you should set the general cache capacity according to the number of areas set in priority mode. This prevents a reduction in general cache performance.
You cannot change a Cache LUN XP extent after it is configured. To change the specification, you must reset (“release”) the Cache LUN XP extent, and then re-allocate (“set”) the Cache LUN XP extent. Starting Cache LUN XP 1. Click Cache LUN in the left pane. The Cache LUN pane appears.
The LDEV tree does not show Auto LUN-reserved volumes because they cannot be used in Cache LUN XP operations. LDEV table Information about the LDEV selected in the tree appears on a single line in the upper-right portion of the pane. It includes LDEV number, emulation type, capacity, and RAID level. The LDEV’s capacity is shown in MB for open systems, or cylinders and tracks for mainframe systems.
Buttons • Set: Creates a cache extent. • Release: Deletes a cache extent. • Apply: Applies the parameters to the disk array. You can then set or release other cache extents. • Cancel: Cancels the operation. Setting (creating) a cache extent 1. In the LDEV tree of the Cache LUN pane, click the CU:LDEV number of the LDEV you want to put in cache. The LDEV table displays Cache LUN XP information for the LDEV you selected. 2.
d. Click OK to continue. The Multi Set pane appears. Figure 3 Multi Set pane e. In the CU drop-down list, click the CU. f. In the table, click more than one LDEV and then click Set. The Multi Set pane closes and the new settings are shown in blue on the Cache LUN pane. To cancel operations, click Cancel. Go to step 10. 9. To place specific data from multiple LDEVs into cache: a. If the Select All Area check box is grayed out, go to the next step.
Releasing (removing) a cache extent 1. In the LDEV tree of the Cache LUN pane, click the CU:LDEV number of the LDEV you want to remove from cache. The LDEV table displays Cache LUN XP information about the LDEV you selected. 2. Select an extent to be removed from the Cache LUN XP cache. The Release button is enabled. 3. Complete one of the following steps: • To remove specific data from cache, go to step 4. • To remove all data from cache, go to step 5. 4. To remove specific data from cache: a.
Changing an extent’s mode and pre-staging You cannot directly change a cache extent’s mode or pre-staging settings. You must delete the extent and reconfigure it with new settings. 1. Select and release (remove) the extent in the Cache LUN XP cache. 2. Remake the extent with the new mode and pre-staging settings.
Cache LUN XP for the XP1024/XP128
Index A logical blocks 10 audience, documentation 5 available space 13 M B battery backup 11 bind mode 11 buttons 14 C cache extents 11 about 9 creating 14 removing 16 size requirements 10 Cache LUN pane 12 conventions document 6 text symbols 6 creating cache extents 14 CU number 12 custom volumes 9 customer support 6 D document conventions 6 prerequisites 5 related documentation 5 E emulation types supported 9 extents, cache 11 about 9 creating 14 removing 16 size requirements 10 F firmware version
