User manual HP STORAGEWORKS XP CONTINUOUS ACCESS SOFTWARE

[. . . ] HP StorageWorks Hitachi TrueCopy for z/OS user guide HP XP12000 Disk Array HP XP10000 Disk Array HP 200 Storage Virtualization System Part number: T171 1-96016 Seventh edition: April 2008 Legal and notice information Copyright 2005, 2008 Hewlett-Packard Development Company, L. P. Valid license from HP required for possession, use or copying. Consistent with FAR 12. 21 and 12. 212, 1 Commercial Computer Software, Computer Software Documentation, and Technical Data for Commercial Items are licensed to the U. S. Government under vendor's standard commercial license. [. . . ] Workloads with large write block sizes, such as DB2 deferred writes, can impact performance. The demand on the MCU's host channels can affect performance. TC390 operations can have a negative impact on workloads with a high percentage of sequential write operations, such as batch processing operations (for example, dump/restore or sort operations). Large cache size improves read hit performance, which allows more disk array resources to be devoted to write operations. The resulting performance improvement can offset some or all of the performance loss due to the TC390 remote copy operations. TC390A and HXRC require additional cache for sidefile data. Insufficient cache resources can result in command retries, SCP notifications, and puncture conditions. Recommendation(s) Spread write-intensive data across several volumes to minimize queuing. Also consider increasing the duplex write line (DWL) of the disk array using Performance Manager. Spread workloads with large write block sizes across several volumes. Spread the workload across several disk arrays to use additional channels. Avoid performing restore operations to volumes that belong to TC390 pairs. Instead, restore data to a scratch volume and then establish the TC390 volume pair. Large block size High host channel demand Sequential write operations Cache size Consider increasing the cache size of the TC390 disk arrays to handle TC390A and HXRC sidefile operations and to improve overall disk array performance. For best results, the cache and NVS capacity of the main and remote disk arrays should be the same (for TC390A the RCU sidefile requirements are 2x that of the MCU) to enable the remote site to function adequately during disaster recovery. TrueCopy for z/OS user guide 115 Table 25 Condition Optimizing TrueCopy operations and XP1024/XP128/XP12000/XP10000 performance Description The performance of the RCUs directly affects the performance of the MCUs. If an RCU becomes overloaded with heavy update activity, MCU and system performance can also be degraded. An inadequate number of Remote copy connection paths may decrease disk array performance. Performing TC390 Synchronous operations over long distances can also degrade disk array performance. TC390A is recommended for long distances. Recommendation(s) Distribute TC390 remote copy operations among several remote disk arrays to avoid overloading any one RCU. RCU capacity Remote copy connection paths Make sure to install an adequate number of Remote copy connection paths between the main and remote disk arrays. This is especially important for disk arrays that contain both M-VOLs and R-VOLs. Discontinuing TrueCopy Operations If you plan to use TC390 for nondisruptive data migration or duplication (see "ICKDSF Considerations for TrueCopy Volumes" on page 137), you will need to configure and establish TC390 operations, allow TC390 to synchronize the volumes, redirect application I/Os (if migrating), and then discontinue TC390 operations. When you are ready to discontinue TC390 operations, you will need to perform TC390 operations in the correct order to avoid generating error messages. For example, you cannot delete an RCU path until you have deleted all TC390 pairs still using that path and you cannot delete a group until you have deleted all TC390A pairs in that group. To discontinue all TC390 operations: 1. Delete all TC390 pairs from the MCU(s) (Delete Pair, see "Deleting TrueCopy Volume Pairs (Delete Pair)" on page 133). For TC390A pairs, you can use the Delete Range-Group option to delete all pairs in a group using just one operation. [. . . ] Level 3: Sidefile capacity exceeds 60% in the total cache capacity. The session that has the largest amount stored in sidefile cache is canceled. 214 TrueCopy for the XP1024/XP128/XP12000/XP10000 NOTE: The XP1024/XP128/XP12000/XP10000 SVP mode settings are preserved, even during microprogram exchange or disk array power-off. Figure 77 Current load balancing control New Load Balancing Control The following conditions are required to activate the new DONOTBLOCK option for the XADDPAIR TSO command: The operating system must support the new DONOTBLOCK option. If Mode 61 is OFF (default), the XP1024/XP128/XP12000/XP10000 performs current load balancing control. If the operating system does not support the DONOTBLOCK option, set Mode 61 = OFF. [. . . ]