Pool Types
There are three types of pools:
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Dynamic
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Static Striped Storage
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Static Spanned Storage
These pool types have distinct advantages and it is important to know the differences before creating pools.
Dynamic
Dynamic pools allow you to add storage on demand by providing “just enough space, just in time.” Use NMVs from a dynamic pool for volumes whose size requirements are not well known ahead of time and when not trying to restrict the amount of storage that the application servers use. The default size of an NMV is 2 terabytes.
When virtual volumes are mapped to application servers, they will see LUNs of the logical size, but the virtual volumes can be resized prior to mapping.
NMVs allocate physical storage in a striped method to these large virtual volumes as demanded by the application servers, allowing your application servers to do their own capacity planning. As the application encroaches on the current physical allocation, additional blocks (SAUs) are taken from the available space in the pool. However, be prepared to add disks to the pool as application servers allocate space and thresholds are approached.
Static striped storage
Static striped storage requires you to enter a fixed size for NMVs created from this pool. Physical storage is pre-allocated at creation. The result is that you will not run out of space in the pool. You must have adequate physical storage to support the volume size you create. If you don’t have adequate storage, the request will fail.
Striping indicates that NMVs allocate the storage in chunks across as many pool disks as possible. This can give you the best performance possible, provided you have assigned several disks to the pool before volume creation to maximize the parallel effect. Use static striped volumes for enhanced speed.
This option is best for volumes whose size can be predicted and whose size is unlikely to grow over time.
Static spanned storage
This option requires you to enter a fixed size for the NMVs created in this pool. Physical storage is allocated at creation. The result is that you will not run out of space in the pool. You must have adequate physical storage to support the size you enter. If you don’t have adequate storage, the request will fail.
Spanning causes the NMV to allocate the storage in chunks across as few pool disks as possible. You need not assign multiple disks to the pool before volume creation; you have the advantage of “adding as you go” without effecting performance.