[Info-vax] Replacement of SCSI tape drives and loaders

[Syltrem]

Hi

I have 2 Alpha servers, each with SCSI connected tape drive(s)

I want to move the drives from one server to another, and install a new one.

QUESTION: Can I do this live ?

My experience (on VAX) is that I can disconnect / reconnect the same drive 
on the VAX and it will not notice, as long as I DO NOT attempt to use the 
drive (do a MOUNT or INIT etc) on it while it is disconnected. Doing so 
would crash the VAX.

On Alpha it may be different, the HP tech says it should work just fine. I 
just want to double check here.

Details :
On the AS4100 I have a standalone DLT4 drive MKB600
On the ES40 I have a TL891 mini-library with 2 DLT4 drives MKA400 and MKA500

I want to disconnect the standalone DLT4 drive from the AS4100 and connect 
the TL891 and its drives in replacement.
On the ES40 in replacement of the TL891 I want to install a new LTO4 drive.

So... the AS4100 will get 2 drives instead of 1, and the ES40 will loose one 
drive and the replacement one will be of a different model.

QUESTIONS:
- Should I care about the new drives SCSI addresses ?
- VMS on the ES40 will continue to see the old device (let's say MKA500 if 
the new one replaces MKA400) which is disconnected. If by mistake some 
process tries to access it, will it cause VMS to crash ?
- If I keep the same SCSI address, does it matter if suddenly (as far as VMS 
sees it) the drive model is different ?
- The speed of the drive is also different. Without a reboot will VMS make 
the best use of the new unit (the speed of the devices on the bus have 
changed) ?

This is NOT something I've done before so I just don't know.
My guess is that I should shutdown the servers to do this, but I'd rather 
not if it's not required (24/365 shop)

Merci
Syltrem