Recording Library stores recordings in an efficient .spx format, which means they won't take up very much space on your server.
A general guideline is 100 KB per minute of recording. This means that with roughly 32 GB, you can record up to 5,500 hours of recordings.
This is enough space to record one agent for a full 8 hours every workday for over 2 years. With 500 GB, you could record 30 agents for 8 hours a day for a full year. Since your agents may not be not talking on the phone for a full 8 hours each day, this space can last even longer.