HP StorageWorks Cache LUN XP user guide for the XP10000/XP12000 Part number: T1716-96002 Second edition: December 2005
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Contents About this guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Intended audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Prerequisites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Firmware versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Related documentation . . . . . . . . . . . . . .
3 4 5 6 7 8 Tables 1 2 3 4 4 Cache LUN pane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Multi Set pane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Multi Release window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PCR cache area (cache extent) . . . . . . . . . . . . . . . . . . . . . . . . . .
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 11 • ”Pre-staging” on page 12 • ”Required cache size for Cache LUN XP” on page 13 • ”Starting Cache LUN XP” on page 16 • ”Setting (creating) a cache extent” on page 18 • ”Partial Cache Residence (PCR) operations” on page 22 Intended audience This guide is
Document conventions and symbols Table 2 Document conventions 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 XP10000/XP12000 Use HP StorageWorks 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 VSC).
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.
Table 3 Restrictions (continued) For example, in Figure 2, the LUSE volume is composed of three LDEVs (00:01, 1,000 LBAs, 00:02, 1,002 LBAs, and 00:03, 1,020 LBAs). If you want to set Cache LUN XP to 500 LBAs starting from LBA number 1,020, you can set Cache LUN XP to 500 LBAs starting from LBA number 20 on the second LDEV, because the first LDEV size is 1,000 LBAs.
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. If the general cache is overloaded (having very little cache space), this can result in a wait for free cache space. This may degrade access to the general cache. • If you set up to 512 areas in Cache LUN XP, set 512 MB x 2 (1024 MB) of standard cache.
Required cache size for Cache LUN XP The required cache size for Cache LUN XP depends on the operation modes. For example, in bind mode, RAID-1 groups require twice the cache size for user data to use Cache LUN XP. However, RAID-5 or RAID-6 groups require three times the cache size for user data to use Cache LUN XP. NOTE: When external volumes are used, twice the cache size is required for user data to use Cache LUN XP.
For specified volumes: a.
NOTE: If a RAID-5 or RAID-6 volume area is changed from priority mode to bind mode and no cache is added, only 33 percent of the user data fits into the area previously assigned for priority mode. The remaining 67 percent is used to save read/write data. If a RAID-1 volume area is changed from priority mode to bind mode and no cache is added, only 50 percent of the user data fits in the area previously assigned for priority mode. The remaining 50 percent is used to save read/write data.
b. Priority mode Required cache size = (Number of addresses × (128 × (512 + 16) ) ) ÷ 1,024 Units are KB NOTE: If a RAID-5 or RAID-6 volume area is changed from priority mode to bind mode and no cache is added, only 33 percent of the user data fits into the area previously assigned for priority mode. The remaining 67 percent is used to save read/write data.
• If you clear this check box and then click Apply, a non-pre-staging operation will be performed, but a pre-staging operation will not be performed. If you select this check box later and then click Apply, only a pre-staging operation will be performed. When a pre-staging operation is in progress, the text Prestaging operation in progress is shown at the bottom of the Cache LUN pane. The progress is displayed in percentage. The Prestaging check box is enabled in Modify mode and is selected by default.
• Start: The starting address for data that will reside in the cache. This is expressed as a logical block address for open systems and as a cylinder and head address for mainframe systems. • End: The ending address for data that will reside in the cache. This is expressed as a logical block address for open systems and as a cylinder and head address for mainframe systems.
b. Clear the Multi Set / Release check box. c. Click Set. A confirmation dialog box appears. d. Click OK to continue. The new settings are shown in blue on the Cache LUN pane. To cancel operations, click Cancel. Go to step 10. 7. To place specific data from an LDEV into cache: a. If the Select All Area check box is grayed out, go to the next step. If the Select All Area check box is activated, clear the Select All Area check box. b.
For open systems, Cache LUN XP identifies a logical area in units of 128 blocks for OPEN-V, and 96 blocks for other than OPEN-V. For OPEN-V, if you have entered 1 as the starting logical block address and a value less than 128 as the ending logical block address, Cache LUN XP automatically changes the ending block address to 128.
c. Click OK to continue. The Multi Release window appears. Figure 5 Multi Release window d. In the CU box, click the CU. e. In the table, click more than one LDEV and then click Release. The Multi Release pane closes and the new settings are shown in blue on the Cache LUN pane. To cancel operations, click Cancel. Go to step 6. 6. To remove cache data for another CU:LDEV, repeat the previous steps. 7. If the deletions are correct, click Apply. A confirmation dialog box appears. 8. Click OK to confirm.
Partial Cache Residence (PCR) operations Overview of the PCR function The XP10000/XP12000 has a special network board that allows the array to be connected directly to a LAN. This network connection interface is called Network Attached Storage (NAS).
2. Click the PCR tab. The PCR pane appears. Figure 7 PCR pane PCR pane The PCR pane displays the table of NAS channels available for PCR operations, as well as a pie chart showing PCR cache usage. You can set the PCR cache size for management information (i-node) and log information used by the NAS channel file system.
• Buttons: • Set: Adds the requested PCR operation (set PCR cache) to the PCR information table. • Clear: Enters 0 (zero) into both the i-node and log fields. • Apply: Starts the requested operations listed in the PCR information table. • Cancel: Cancels the requested operations and resets the PCR information table. Viewing the current PCR settings You can view the current PCR settings in the PCR pane.
Index A M audience, documentation 5 available space 17 memory requirements 9 modes settings 21 types of 11 B battery backup 12 bind mode 12 buttons 18 O C P cache extents 12 about 9 creating 18 removing 20 size requirements 10 Cache LUN pane 16 CLPR drop-down list 16 conventions, document 6 creating cache extents 18 CU number 17 custom volumes 9 customer support 6 Partial Cache Residence (PCR) 22 PCR (Partial Cache Residence) 22 PCR pane 23 pie chart 17 prerequisites 5 pre-staging about 12 enabling
Figures 1 2 3 4 5 6 7 8 Cache LUN XP operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Example of LBA value setting with LUSE volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Cache LUN pane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Multi Set pane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Multi Release window . . .
Tables 1 2 3 4 Recommended and minimum firmware versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Document conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Cache LUN XP icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
