How To Set Flash Pool Policies?

In the blog posts “Flash Pool Read Policies” and “Flash Pool Write Policies”, I discussed what are the Flash Pool policies. But, how do you set these policies? So far, I’ve only discovered one way to do it: by using node CLI. Below are some examples.

Suppose you have two database FlexVol volumes (db1_fv, db2_fv) and two log volumes (log1_fv, log2_fv). Let’s say you want to cache random reads and random writes for both database volumes; and you don’t want to cache anything for the log volumes.

First of all, in order to set Flash Pool policies, you need to use the diag mode. Figure 1 below shows how to switch to the diag mode.

Figure 1. Setting the diag mode.

Now, we can actually set some Flash Pool policies. Figure 2 shows how this can be done. Note that the policies are set for each volume separately.

Figure 2. Setting the Flash Pool policies.

Figure 3 shows how you can verify the settings on the per-volume basis.

Figure 3. Checking the settings.

That’s it. In summary, for each volume, you can set a read-cache policy and a write-cache policy.  The syntax of the command is:

priority hybrid-cache set <volume name> <read-cache>=<value> <write-cache>=<value>

Thanks for reading.