Additional volumes should have annotation data to indicate usage

[burmanm]

What is missing?

Currently, we do PVC size calculation on the "server-data" volume for decommission purposes. If user is using multiple server-data directories, we do not take into account their sizes when calculating available space.

This is because we do not know what the additional PVCs linked to the container are used for. Only a single data directory is acceptable right now.

We could either use separate CRD entities showing "additionalWALDirectory" and "additionalServerDataDirectories" or then allow manually annotating those volumes in the CRD to indicate their purposed usage.

Why is this needed?

For all operations that might need to do which disks are used for which purpose. This could mean backups / WAL processing / etc.

┆Issue is synchronized with this Jira Story by Unito
┆Issue Number: CASS-13