IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

56 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

Volumes for an isolated workload should be created as evenly as possible across all Ranks

allocated to the isolated workload and similarly, volumes for a resource-sharing workload

should be created as evenly as possible across all Ranks allocated to the resource-sharing

workloads. Host-level striping (open systems Logical Volume Manager striping or z/OS

Storage Groups) should then be used across all the volumes belonging to the workload.

One exception to the recommendation of spreading volumes is the case of files or datasets

which will never be accessed simultaneously, such as multiple log files for the same

application, where only one log file will be in use at a time.

Host connections should also be configured as evenly as possible across the I/O adapters

available to either an isolated or a resource-sharing workload. Where possible, do not share a

host adapter connection with remote mirroring traffic.

3.1.4 Using isolation, resource-sharing and spreading to optimize the DS6000

performance

A recommended approach to optimizing performance on the DS6000 is to begin by

identifying any workload that has the potential to negatively impact the performance of other

workloads, or to have its performance negatively impacted by other workloads.

The next step is identifying balanced hardware resources that can be dedicated to the

isolated workload.

The third step is identifying the remaining DS6000 resources to be shared among the

resource-sharing workloads.

The final step is assigning volumes and host connections to the workloads in a way that is

balanced, and spread - either across all dedicated resources (for the isolated workload) or

across all shared resources (for the multiple resource-sharing workloads).

3.2 Isolation requirements

The first and most important step in creating a successful logical configuration for the DS6000

is analyzing the workload characteristics for the applications that will access the DS6000 so

that DS6000 hardware resources such as RAID arrays and I/O ports can be properly

allocated to workloads. This workload analysis should be done during the DS6000 capacity

planning process and should be completed prior to ordering the DS6000 hardware.

3.2.1 Review the application workload characteristics to determine the

isolation requirements

A critical piece of the workload analysis is identifying workloads which require isolated or

dedicated DS6000 hardware resources, because this will affect the total amount of disk

capacity required, as well as the type of disks and the number and type of I/O adapters. For

DS6000 disk allocation, different levels of isolation requirements may dictate the use of

separate Ranks, or even separate DS6000 Storage Images. For DS6000 I/O port allocation,

different levels of isolation requirements may dictate the use of separate I/O ports.

Workloads which require different disk drive types (capacity and speed), different RAID types

(RAID5 or RAID10), or different storage types (CKD or FB) require isolation to different

DS6000 arrays. Workloads that use different I/O protocols (FCP or FICON) require isolation

to different I/O ports. Organizational considerations may also dictate isolation (for example,