Merging two storage pools
The Merge Storage Pool method expands capacity by "combining" a used storage pool with either a new storage pool or an existing, less used storage pool.
Before you begin
- Only two storage pools can be merged at a time.
- Storage pools can be merged regardless of the Slicestor® device models that are used in the pools.
- After the storage pools are merged, the new pool capacity is the sum of the capacities that are associated with the original storage pools.
- All vaults that are associated with the original storage pools now become visible to the new merged storage pool.
- Storage pools of any size can be merged when no vaults exist on either pool. However, after the
storage pools are merged, only vaults that are a divisor of both the storage pool widths can be
created. It is advantageous in many circumstances, but exceptions exist.
For instance, Pool1 (Width = 8) and Pool2 (Width = 9), where both Pool1 and Pool2 do not have any vaults. After the pools are merged, a user can create vaults of size 1.
- Storage pools of the same width can be merged irrespective of the number and size of vaults on either pool.
- If the storage pool widths are different and vaults exist, the width of each pool must be an
exact multiple of the width of all the vaults that exist on either pool. This scenario allows larger
or smaller capacity storage pools to be merged.
Given Pool1 (Width = 8) with vault11 (Width = 8) and vault 12 (Width = 4) and Pool2 (Width = 16) with vault21 (Width = 8), Pool1and Pool2 can be merged.
- Some storage pools cannot be merged.
Given Pool1 (Width = 8) with vault1 (Width = 8) and Pool2 (Width = 16) with vault2 (Width = 16), Pool1 and Pool2 cannot be merged since vault2 cannot be associated with Pool1 after the merge. Such options are not presented on the Merge Storage Pool page in the Manager Web Interface.
Follow these steps when you merge storage pools. Storage pools can be merged in any order.
- Pool_test1 is the original storage pool.
- Pool_test2 is either a new storage pool or another storage pool that has lower usage when compared to Pool_test1.
About this task
With this approach, two storage pools, along with all vaults across these storage pools, are merged together. Only two storage pools can be merged at a time. More storage pools can be merged with the newly merged storage pool over time as needed. After the pools are merged, the new pool capacity is the sum of the capacity that is associated with the original storage pools. All vaults that are associated with the original storage pools now become visible to the merged storage pool.
When two storage pools are merged, two sets are formed. Set 1 contains the devices that are associated with the first storage pool, and Set 2 contains the devices that are associated with the second storage pool. The set names (Set 1, Set 2) cannot be edited. When a new vault is created, its width must be the same as a smaller of the two set. Also, when writes are performed to a vault in the merged storage pool, the objective is to fill the storage pools evenly. Thus, writes are adjusted based on the capacity available within individual sets. As an example, if both sets have equal capacity available, writes are ~50/50 across the sets. However, if one set is full and the other is empty, writes are 0/100.
Procedure
What to do next
The storage pool name that is retained after the merge depends on the storage pool from which the Merge Storage Pool operation was initiated (Steps 3 and 4).
In this example, Pool_test1 was used. As a result, the name of the new merged storage pool (after Step 6) is Pool_test1.