Enable FAST - VNX5300 Existing pool

FAST or FAST Cache ? With just 3 drives i would use them for Fast Cache instead.

FAST VP .

Obtain the license (normally through a suite like the Essential s Pack or FAST Suite).

For either FAST Cache or FAST VP, you'll need to install the license (enabler) using Unisphere Service Manager (USM).

For FAST cache alone, I don't think SP reboots are required, but in a  proper multipath environment it's NDU anyway.

As Dynamox says, with only 3 drives you'd be best served configuring FAST Cache. So after installing the enabler, insert the drives and create the FAST Cache from the System Properties, Fast Cache tab. Configure 1 drive as a Hot-Spare.

Then enable FAST Cache on your Storage Pool. The cache will then profile your I/O and it will "warm-up" and you will see results.

why cache ? can you guys explain further as far as I knew its only for caching

When you add new disks to an existing Pool like the EFD disks, you need to add an amount of EFD that matches the level of performance that you want. For a normal Pool with existing SAS disks, you should add at least 5 EFD for a Raid 5 tier (4+1) and you'll need one more for a hot spare. So adding EFD to an existing Pool you would need at least 6 if using Raid 5 5 for the Pool and one for the hot spare). If you only have three EFD, then you need one for a hot spare, that leaves two EFD. With two EFD you could add that to the Pool as a Raid 1/0 (1+1). But for this to be efficient you would need FAST VP to ensure that the hot slices in the SAS tier will move up to the EFD tier. But with only two EFD in Raid 1/0, the amount of free space will be the amount in one EFD. That will only hold a limited amount of data.

Using the two EFD for FAST cache might give you better performance as the hot slices would be promoted to FAST Cache as you use them. With FAST VP, the hot slices get moved each night when auto-tiering is run and the next day you might find that the hot slices you moved up during the night are no longer used and the new hot slices are still on the SAS disks will not be in the EFD tier (but they will move up when Auto-tiering runs that night). With FAST cache, the cached hot slices are moved out when no longer needed, making room for new hot data. You don't have to wait for Auto-tiering to run each night.

Also, you will need to check that the type of EFD you have is supported for Pools - there are two types of EFD - one for Pool use and one for FAST Cache use.

If you use FAST Cache, then you'll need the enabler for FAST Cache along with the FAST VP enabled. FAST VP will still improve the performance of a single tier Pool (say all SAS disks) by re-balancing the hot workload over all the disks in the Pool. Without FAST VP you could end up with certain subsets of the disks holding data that is very hot and not spread over all the disks.

glen