An average block is about 1 MB in size. Although it seems that max. 4 MB is allowed. So 4 (MB) x 6 (10 minutes per hour) x 24 (hours per day) x 365 (days per year) x 15 (years of the timechain) = 3.1 TB Looks like we're still good with 1.6 TB. 😅🙈