For the static files.
1 Tb = 10^12 bytes.
If your files have 10^4 bytes on average, then
your site hits the storage ~ 10^8 times per month.
The ordinary mechanical HDD can serve
this load, if it will be distributed steadily.
Yet better, if the files, which are
requested frequently, are cached.
The problem is, that the load may
have the sharp peaks, during which the
mechanical HDD may be too slow.
If your files are not static,
but are generated on the fly,
especially with many requests
to the storage for every file
(like the pages from the content
management systems), then,
most probably, the mechanical
HDD will not be able to serve
your load during the peaks.