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

[Christoph Gartmann]

In article <ZF16n.101149$dl4.56657 at en-nntp-03.dc1.easynews.com>, "Syltrem" <syltremzulu at videotron.ca> writes:

>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 ?

It depends ;-)

>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.

As long as you take care of the SCSI bus, that is, try to prevent any activity
on the bus while connecting/disconnecting, you should be fine.

[...]
>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 ?

Of course, the general SCSI-ID rules apply (different IDs, don't use the ID
of the controller,...)

>- 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 ?

No, the process might just hang.

>- If I keep the same SCSI address, does it matter if suddenly (as far as VMS 
>sees it) the drive model is different ?

Do a "MC SYSMAN IO AUTOCONFIGURE" afterwards and you should be fine.

>- 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) ?

As long as there is no slower device on the bus, yes, it will.

Good luck
   Christoph Gartmann

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