Configuration planning for the SAN Volume Controller

Ensure that you perform all the required and necessary planning tasks before you start to configure your SAN Volume Controller environment.

Planning the clusters

Determine the following information for clusters:

The number of clusters and the number of node pairs (I/O groups). Each pair of nodes is the container for one or more virtual disks (VDisks)
The number of hosts that you want to use
The number of I/Os per second between the hosts and nodes

Planning the hosts

VDisk host mapping allows the hosts to access specific logical units (LUs) within the storage systems. Determine the following information for hosts:

For hosts using a SCSI over fibre-channel connection, the worldwide port names (WWPNs) of the fibre-channel (HBA) ports on the hosts
For hosts using an iSCSI over Ethernet connection, the IQN of the host and the authentication credentials
The names to assign to the hosts.
The VDisks to assign to the hosts.

Planning the MDisks

To plan the managed disks (MDisks), determine the logical or physical disks (logical units) in the storage systems and in any SAN Volume Controller 2145-CF8 solid-state drives (SSDs).

Planning the managed disk groups

Determine the following information for MDisk groups:

The types of storage systems that you want to use.
If you want to create VDisks with the sequential policy, plan to create a separate MDisk group for these VDisks or ensure that you create these VDisks before creating VDisks with the striped policy.
Plan to create MDisk groups for the storage systems that provide the same level of performance or reliability, or both. For example, you can group all of the managed disks that are RAID 10 in one MDisk group and all of the MDisks that are RAID 5 in another group.
Plan the extent size of the managed MDisk group. For example, a larger extent size increases the total amount of storage which the SAN Volume Controller can manage. A smaller extent size provides more fine-grained control of storage allocation. Extent size does not affect performance.

Planning the VDisks

An individual VDisk is a member of one managed disk group and one I/O group. The managed disk group defines which MDisks provide the back-end storage that makes up the VDisk. The I/O group defines which nodes provide I/O access to the VDisk. Before you create a VDisk, determine the following information:

If the VDisk should be created in image mode from a managed disk that contains data that needs to be preserved.
The name that you want to assign to the VDisk.
The I/O group to which the VDisk will be assigned.
The managed disk group to which the VDisk will be assigned. For example, different managed disk groups could have different performance characteristics depending on the storage that is contained by that managed disk group.
The capacity of the VDisk.
If you want to provide extra redundancy by mirroring the VDisk across managed disk groups. For example, you could use the VDisk Mirroring feature to provide redundancy across managed disk groups.
If you want to create fully allocated VDisks or use space-efficient virtual disks.
The cache mode for the VDisk is either readwrite or none. The default is readwrite.

Consider the effect that the FlashCopy, Mirroring, and space-efficient VDisk features have on performance. The effect depends on the type of I/O, and is calculated using a weighting factor.