Lunatic Magnet wrote:
I have a Dell TL1000 LTO-8 library with the latest firmware (April 10 2018) and tapes are showing 10.9TB capacity. Looking at some older LTO-6 tapes which have 2.5TB raw, they come up as 2.3TB in Veeam. 2.3TB is 88.46% of the raw capacity. 10.9TB is 90.83% of the raw capacity.
I'd say that's pretty close, but unfortunately like the usable size of hard drives, the larger the tape capacity the more you lose.
You're not really losing anything, it's just the conversion from terabytes, which is used by storage vendors to advertise capacity, to tebibytes, which is used by the OS (and Veeam as far as I know) to display capacity. The confusion comes in that they both use the same abbreviation of TB to refer to these two different things. Technically, I'd say it's the OS that is "wrong" since the abbreviation for tebibyte is TiB, but would anyone know what that is? Even if they did, technically it's the JEDEC 100B.01 standard that defines the "common usage" of KB/MB/GB uses power of 2 values, so it's not really wrong per-se. Basically, in common computer usage people know that a KB=1024 bytes, but storage manufacturers use KB=1000 bytes.
2.5 Terabytes = 2.27375 Tebibytes which rounded is 2.3 and thus is displayed by the OS as 2.3TB. For LTO8, that 12 terabytes = 10.9139 tebibytes which, when rounded, is displayed as 10.9 TB.
For a little deeper dive into the math, the LTO8 capacity is 12,000,000,000,000 (12 trillion) bytes. If you divide by 1,000,000,000,000 (one terabyte) then that's 12 terabytes. However, the computer uses 2^40 bytes which is 1,099,511,627,776 bytes (1024*1024*1024*1024 instead of 1000*1000*1000*1000). 12,000,000,000,000/1,099,511,627,776 = 10.91393642127514 tebibytes. Note that you still have all 12 trillion bytes, it's just the OS is displaying tebibytes instead of terabytes.
It's probably easier to just use Google to convert between them, 12 terabytes is equal to 10.9 tebibytes