Correct amount of disk space

[tgreene1]

I just purchased a readynas 3200 with 12 2TB drives. I set them up for a raid 5, why do I only see 19 TB usable space? All the drives are online. I know with raid 5 one drive is for parity thanks.

[dbott67]

Some of it has to do with the conversion from TB to TiB (marketing folks like to use 1 MB = 1,000 B, while computers use 1 MB = 1,024 B). So, in reality a 2 TB drive is really 1860 GB to a computer, while the rest is overhead, OS and snapshot space.

Using the developers formula: http://www.readynas.com/kb/faq/boot/why ... n_expected

12 x 1.86 TiB = 22.32 TiB
Less 1.86 TiB for parity = 20.46 TiB
Less 2% overhead (approx. 400 GiB) = 20 TiB
Less snapshots 5% (approx. 1 TiB) = 19 TiB