IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

Chapter 6. IBM TotalStorage SAN Volume Controller attachment 181

This mode implies that vDisk0 will assign sequentially one SAN Volume Controller Extent

from mDiskA then, one SAN Volume Controller Extent from mDiskB and one Extent from

mDiskC and so on. vDisk0 will assign the first 34 Extents of mDiskA, the first 33 of mDiskB

and the first 33 of mDiskC.

In this case, all the SAN Volume Controller Extents assigned for vDisk0 are physically located

on Rank1, Rank2 and Rank3 of the DS6000. This configuration permits you to spread the

workload applied on vDisk0 to all three Ranks of the DS6000. In this case we efficiently use

the hardware available for each vDisk of the Managed Disk Group.

6.2.4 DS6000 volumes consideration

This section details the recommendations regarding volume creation on the DS6000 when

assigned to SAN Volume Controller.

Number of volumes per Extent Pool

The DS6000 provides a mechanism to create multiple volumes from a single Extent Pool.

This is useful when the storage subsystem is directly presenting storage to the hosts.

In a SAN Volume Controller environment, however, where possible, there should be a

one-to-one mapping between Extent Pools and Volumes. Ensuring that the Extent Pools are

configured in this way will make the subsequent load calculations and the managed disk and

managed disk group configuration tasks a lot easier.

Volume size consideration

As we recommend to define one volume per Extent Pool, the volume size will be determined

by the Extent Pool overall capacity.

If this recommendation is not possible in your specific environment, at least we recommend

you to assign to SAN Volume Controller DS6000 volume of the same size. In this

configuration, workload applied on a Virtual Disk will be equally balanced on the Managed

Disks within the Managed Disk Group.

6.2.5 Volume assignment to SAN Volume Controller cluster

On the DS6000, we recommend creating one Volume Group in which will be included all the

Volumes defined to be managed by SAN Volume Controller and all the Host Connection of

the SAN Volume Controller nodes ports.

6.2.6 Number of paths to attach the DS6000 to SAN Volume Controller

To avoid any performance limitation in the SAN Volume Controller-to-DS6000 communication,

we recommend you to assign all the host ports available on the DS6000 servers to the SAN

Volume Controller cluster. In this configuration, four active paths are used to access to one

volume defined on your DS6000.

Important: The configuration presented in Figure 6-6 on page 180 is optimized for

performance in an SAN Volume Controller environment.

Note: For SAN Volume Controller attachment to the DS6000, we recommend to use FC

ports from Server0 and Server1 to improve the DS6000 access availability