Storage configuration planning

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Complete all storage configuration planning tasks before you configure your system environment.

Planning the systems

Determine:

The number of hosts to use.
The number of I/Os per second between the hosts and nodes.

Planning the hosts

Host mapping provides a way for hosts to access specific logical units (LUs) within the storage systems. Determine:

For hosts that use an Internet Small Computer System Interface (iSCSI) over Ethernet connection, the iSCSI qualified name (IQN) of the host and the authentication credentials.
The names to assign to the hosts.
The volumes to assign to the hosts.

Planning the MDisks

To plan the managed disks (MDisks), you must complete the following:

If you are installing IBM Spectrum Virtualize for Public Cloudsoftware in an IBM Cloud® environment, you must purchase and configure block storage from the IBM Cloud.

Determine whether to configure endurance or performance block storage:

Endurance storage

Endurance storage is selected from a tier that features a predefined performance level. IBM Cloud supports four options for endurance storage:

0.25 IOPS per GB for low intensity workloads
2 IOPS per GB for general-purpose workloads
4 IOPS per GB for higher-intensity workloads
10 IOPS per GB for demanding workloads

Performance storage

Performance is a class of block storage that is designed to support high I/O applications with that have well-defined performance requirements that cannot be accommodated by the tiers in endurance storage. You can select the GB and a range of IOPS for the size of your storage.

The following table displays the range of GB and the IOPS that is available for Performance storage:

Table 1. Performance storage
Size in GB	Minimum IOPS	Maximum IOPS
20	100	1000
40	100	2000
80	100	4000
100	100	6000
250	100	6000
500	100	6000 or 10000¹
1000	100	6000 or 20000¹
2000 - 3000	200	6000 or 40000¹
4000 - 7000	300	6000 or 48000¹
8000 - 9000	500	6000 or 48000¹
10000 - 12000	1000	6000 or 48000¹

¹IOPS above 6000 are only available at some data centers.

Planning the storage pools

Necessary activities:

Determine the types of storage systems to use.
To create volumes with the sequential policy: plan to create a separate storage pool for these volumes, or ensure that you create these volumes before you create volumes with the striped policy.
Plan to create storage pools for the storage systems that provide the same level of performance, reliability, or both performance and reliability.
Plan the extent size of the storage pool. For example, a larger extent size increases the total amount of storage that the system can manage. A smaller extent size provides more fine-grained control of storage allocation. Extent size does not affect performance.
If you are attaching more than 4 PB of storage to a system, you are not able to use all this capacity with the default extent size of 1 GB. Run the following CLI command one time to enable support for larger extent sizes in the GUI.
```
chsystem -guiadvancedpool yes
```

Planning the volumes

An individual volume is a member of one storage pool and one I/O group. The storage pool defines which MDisks provide the back-end storage that makes up the volume. The I/O group defines which nodes provide I/O access to the volume.

Consider the effect that FlashCopy®, Global Mirror, Metro Mirror, and thin-provisioned volumes have on performance. The effect depends on the type of I/O, and is calculated by using a weighting factor.