Flash Pool is a new feature in Data ONTAP 8.1.1. Basically, it is a pool of solid state disks (SSD) plus either SATA or SAS disks (but not both SATA and SAS in the same pool).
Create a Flash Pool
Flash Pool is implemented in the Data ONTAP aggregate layer. To construct a Flash Pool, you use the follow three steps and in that order.
1. Create a 64-bit aggregate using either SATA or SAS hard drives as usual (see Figure 1)
Figure 1. Create a 64-bit aggregate with SATA drives.
2. Enable the aggregate option hybrid_enabled as shown in Figure 2
Figure 2. Set the aggregate option hybrid_enabled to on.
3. Add SSDs into the aggregate created in Step 1 above (Figure 3)
Figure 3. Add SSDs to the aggregate.
Now you have just created a Flash Pool with a combination of SSDs and SATA hard disk drives.
Use the Flash Pool
After you have created a Flash Pool, you want to use it. But how?
It is pretty straight forward. To use a Flash Pool, you create FlexVol volumes and LUNs within it, just as you would do with a normal Data ONTAP aggregate. Figure 4 below shows the example of how to create a FlexVol volume using the Flash Pool fpAggr.
Figure 4. Create a FlexVol volume using the Flash Pool fpAggr.
Next, you create and map a LUN or several LUNs to a host and then you are good to go.
When you run your workload on a Flash Pool, your workload doesn’t know (no need to know) it is running on a Flash Pool. But you will notice that it is running faster, because the hot (frequently used) data is going to be placed on SSD and the other data on SATA or SAS drives. And the good news is that you don’t need to tune it manually to place the data properly. Flash Pool will manage the data placement for you automatically.