The first step in configuration for tag-based protection is to create a new tag category. You can create a single category or you can create multiple categories if you prefer. It depends on how you want to manage your environment.
Tag categories and tags can be considered to be similar to key/value pairs that are just separated into two different objects- the category being the key and the tag being the value. So a category could be something like "array replication pair" and the tag could be "x20 to x70". How the administrator decide to use tags is up to the administrator- the main point is that in order for SRM to be able to add datastores into a protection group, they must have at least one tag which is included in at least one storage policy.
There are a few things to answer:
- How many categories should there be- one or more?
- Does that category allow one or more tags from that category on one object?
- What should the tag value be?
How you answer these questions is up to the administrator. There are not strict rules on how this should be done; it is purposefully flexible. Do what makes sense in the environment. The most important part is consistency. Come up with a framework and be consistent with how it is implimented.
The important thing to remember is that tags are not "intelligent". If they describe a setting (like replication interval) and someone changes the replication interval on the FlashArray software for that volume, the tag may no longer be correct. Generally, focus on tagging datastores so they are properly grouped and take care to enforce strict change control of replication.
One more point to note is that if your vCenter Server instances are connected via Enhanced Linked Mode, tags and tag categories are replicated across all these vCenter Server instances upon creation and there is no need to create them for each vCenter. If the vCenters are not connected via ELM, there must be manually be created tag categories and tags in each vCenter. Both options are supported, but linking vCenters via ELM is generally recommended.