Optimizing Continuous Access Xp Operations And Disk Array Performance - HP StorageWorks XP12000 User Manual

Statistic
Number of Remained
Recordset
Scheduling Attempt Count
Synchronization
Pair Synchronized (%)
Out of Synchronous Tracks
Cache
SideFile[%]
The usage monitor graph closes automatically in the following cases:
• Stopping the usage monitoring function by clicking Stop in the Operation drop-down list, and
clicking Apply.
• Clicking another tab.
• Exiting Command View XP or XP Remote Web Console.

Optimizing Continuous Access XP operations and disk array performance

Continuous Access XP operations result in increased utilization of the disk array's channel resources
because of additional write (remote copy) operations to secondary volumes. The Continuous Access XP
update copy mode (synchronous or asynchronous) determines exactly how the remote copy operations
impact disk array performance as follows:
• Synchronous copy mode has an additional effect on disk array performance: increased service
and disconnect time for write I/Os to Continuous Access XP P-VOLs due to the delay between
channel-end and device-end. The length of this delay increases as the distance between the
P-VOL and S-VOL increases, so the longest delay occurs when primary and secondary volumes
are the maximum distance apart.
• Asynchronous copy mode (Continuous Access XP Asynchronous) eliminates all delays associated
with Continuous Access XP Synchronous operations while providing protection for write-dependent
applications if a disaster occurs. Write I/Os for Continuous Access XP Async P-VOLs are
processed the same way as writes for simplex volumes, without any increase in service or
disconnect time. Asynchronous S-VOL updates are performed completely independent of all host
I/O processes at P-VOLs, and there are no restrictions on subsequent read and write operations
to Continuous Access XP Async P-VOLs. The only performance concerns for Continuous Access
XP Asynchronous are:
• Ensuring adequate cache resources are available for sidefiles used to store recordsets at
MCUs and RCUs
• Ensuring sufficient Fibre Channel paths are defined for copy operations
In addition to Continuous Access XP update copy mode, several other factors can also affect disk array
performance. You can optimize Continuous Access XP operations and I/O performance of disk arrays
by analyzing workloads and addressing system-level conditions (for example, number of Fibre Channel
paths) that can affect disk array performance. You can also control the impact of Continuous Access
XP operations on disk array performance by selecting the appropriate RCU options for each MCU (see
Registering RCUs (Add RCU)
update copy mode (synchronous or asynchronous) and pair options (see
volume pairs (Paircreate)) for each Continuous Access XP pair. In addition, you can upgrade Continuous
Access XP hardware components and adjust the configuration of components to improve disk array
performance under a wide range of operating conditions.
Description
Number of remaining recordsets when the schedule is completed
Number of job activations of consistency manager
Percent completion of initial copy operations. For example, number of
synchronized pairs/total number of pairs.
Number of tracks that have not yet been copied by initial copy or resync
copy operations. This applies only when suspended during initial copy or
during resync copy.
You can select only this option when you select Subsystem Total or CLPR in
Select LU on the Display Item pane.
and Modifying RCU options (Change RCU Option)) and the appropriate
Creating Continuous Access XP
Continuous Access XP user guide
97