Redshift svv_table_info pct_used

Question

From the docs for svv_table_info, pct_used is

Percent of available space that is used by the table

So then I wondered, what is the defintion for 'available space' ? Google led me to an article that said this :

The query below will give you the percentage of storage used in your cluster, which you can use to check if this is the reason for slow query performance. If you’re nearing capacity (80% or greater), consider adding some more nodes or truncating some unused historical data.

SELECT sum(pct_used) FROM svv_table_info;

That doesn't make sense, as svv_table_info only shows you tables in the current database, not for all tables in all databases the cluster, so could never reflect cluster capacity !?

I ran that query in 1 database and it resulted in 0.9490 So is it telling me that the current Database is at 94% capacity ? If so, what defines the capacity for each of my numerous databases within the cluster ?

Logging in to the AWS console, my cluster is running at 1% capacity.

Can anyone help me make sense of all this please ? I'm sure its very simple, but finding documentation seems to be sketchy.

Thanks