Conference ssdevo::hsz40_product

749.0. "Single HSZ40-BF support question" by DECIDE::MOFFITT () Fri Jan 24 1997 11:29

I'm confused...

I went to visit with a good Digital customer (new to me) who's been buying
HSZ40-Bx controllers for his mission critical applications. To eliminate 
single points of failure (i.e. KZPSA or a SCSI cable) he has two separate
FWD bussed with a single HSZ40-BF controller hanging off each bus. Each
controller has about a dozen drives hanging behind it and most of those drives
are configured as RAID1 sets. The customer then uses host based shadowing to 
mirror across the controllers to eliminate any single point of failure. The
drives are NOT ported between the controllers - the HSZ40s and drives are
completely isolated on their respective busses.

Here's an admittedly poor diagram:

 ______________                             ______________
|              |                           |              |
|	 KZPSA-|------------HSZ40----------|-KSPSA        |
|System A      |            Drives         |      System B|
|	 KZPSA-|------------HSZ40----------|-KSPSA        |
|              |            Drives         |              |
|______________|                           |______________|

The support guy with me (I'd never met him before the meeting either) during
discussions with the customer stated that a configuration with two systems and
a single HSZ40 WAS NOT supported and that the single controllers would have
to be upgraded to dual controllers to be supported.

The customer was taken aback by this as he'd paid to have the systems 
integrated and tested before they were shipped to him. He felt that since
Digital configured, built, and qualified the system, it should be supported.

So here's the question - are there any support issues with a single HSZ40
when it's shared between two systems?

Basic info.

2 AlphaServer 2100s
VMS 6.2-1H?
2 KZPSAs per 2100
1 HSZ40-BF per bus (2 total per system)
HSOF V2.7 (and previously HSOF 2.5)
12 RZ29B-VA drives per HSZ40-BF


Thanks,
tim moffitt

    Tim,
    
    This looks okay, but ensure that the contollers that are being used
    as single controller subsystems, are in seperate BA350-M shelves.
    
    Dual controllers are not related to dual system.
    
    Bert
    

Bert,

Thanks for the quick answer.

The HSZ40s are definitely in separate controller boxes and each controller feeds
3 BA350s, each of which is running in split-bus mode.

The customer should sleep better tonight ;^)

enjoy,
tim m.