Seagate has introduced the Exos M series, a range of enterprise-grade mechanical hard drives available in 30TB and 32TB capacities. The two models, the 30TB CMR ST30000NM004K and the 32TB SMR ST32000NM003K, each offer a minimum of 3TB per disk and use a standard 3.
If you’re writing 100 MB/s, it’ll still take 300,000 seconds to write 30TB. 300,000 seconds is 5,000 minutes, or 83.3 hours, or about 3.5 days. In some contexts, that can be considered a long time to be exposed to risk of some other hardware failure.