Ummmmm ...
Perhaps there's something in the V245's Service Manual ?
( such as Chapter 2 of that 14MB PDF ? )
There's a link to the system's complete documentation in the Sun System Handbook.
http://sunsolve.sun.com/handbook_pub/Systems/SunFireV245/SunFireV245.html
See "Related Documentation" on that page.
Didn't you even peek at the service manual?
Chapter 2
It starts with ...
" The hard drives in the Sun Fire V215 and V245 servers are hot-pluggable,
but this capability depends on how the hard drives are configured. "
... then it goes on from there.
Installation of new disks is covered by section 2.2.2, to be specific.