RMALOUF@SBCCMAIL.BITNET (Rob Malouf) (07/07/87)
Hello,
I have two questions that I hope someone out there can answer. First, do
I really need software checksums in my VAX backups? I have read that they are
not really necessary and only degrade performance. Does anyone have any
experience with not using them? Any comments? I am running a VAX 11/730 with
VMS 4.5 and a Cipher 990 GCR CacheTape 9-track tape drive for backups.
My next question may be a little more difficult. In the next few weeks, we
will be upgrading our site from a lowly VAX 11/730 to a VAX 8530 with a
VAXstation II/GPX networked to it and six diskless VAXstation 2000s in a
Local Area VAXcluster with the 8530 as a boot node. Unfortunately, we could
not afford network hardware/software for the 11/730, so it will not be part of
this configuration. However, I noticed in the documentation that an RA81
disk drive can be driven by two UDA50 controllers. If this is really true,
then I could connect the 11/730's RA81 to controllers in both machines.
This kind of dual-porting would create a shared disk drive and a "poor-man's"
VAXcluster! All my instincts say that it could never work, but why not? Has
anyone actually tried this? And by the way, does anyone know how I can get
the _Guide_to_Local_Area_VAXclusters_? It is mentioned in the documentation
for MicroVMS/WS, but I did not receive it with the LAVC software, and I can't
even find it in the Winter/Spring 1987 _Software_Documentation_Products_
Directory_!
Any help anyone can give me would be GREATLY appreciated. Thank you.
Rob Malouf
Marine Sciences Research Center
State University of New York
Stony Brook, NY 11794-5000
RMALOUF@SBCCMAIL.BITNETgarry@batcomputer.UUCP (07/09/87)
In a recent article RMALOUF@SBCCMAIL.BITNET (Rob Malouf) wrote: >... However, I noticed in the documentation that an RA81 >disk drive can be driven by two UDA50 controllers. If this is really true, >then I could connect the 11/730's RA81 to controllers in both machines. >This kind of dual-porting would create a shared disk drive and a "poor-man's" >VAXcluster! All my instincts say that it could never work... A shared disk drive does not a Vaxcluster make. The only reason people dual-port disks on VMS, I think, is so that they can be manually switched (without having to move cables) over to machine B if machine A goes down. More seriously, Dec says you can't plug an RA81 into a microVax (at least our uVax's) at all - seems Dec screwed up such that the necessary cabling would break FCC rules. I assume that that means there would be "too much" RF leaking out of the cabinet. As a result of this, we are in the process of throwing away our RA81's and - after years of loyalty - buying non-Dec disk drives. garry wiegand (garry@oak.cadif.cornell.edu - ARPA) (garry@crnlthry - BITNET) PS - if you *do* have a dual-ported disk it might be a fun exercise to persuade VMS that it's "actually" an Ethernet... no technical reason why it couldn't be done. Performance from the "remote" node would be terrible though.