That will work fine.

The LTO standard says that any drive can read *and *write one generation
back, can read 2 generations back.

So LTO4 drives can both read and write LTO3 cartridges.  (You still get the
speed and capacity of LTO3 on those cartridges.)

Your LTO4 drives can read LTO2 cartridges, but not write to them.

If you upgrade your drives to LTO5 in the future, then your existing LTO3
cartridges could be read, but not written to.  So it would be easy to read
the data to convert to LTO5, but you could not write to the LTO3 cartridges
again.





On Sat, Nov 14, 2009 at 12:36 AM, Mehdi Salehi <
iranian.aix.support AT gmail DOT com> wrote:

> I do not mean different drives, but different cartridges of different LTO
> generations. e.g a library has two LTO4 drives and mix of LTO4 and LTO3
> cartridges.
>