[Info-vax] question on HBVS and SHOW DEVICE

[Paul Sture]

In article <l2j9o9$gtv$1 at online.de>,
 helbig at astro.multiCLOTHESvax.de (Phillip Helbig---undress to reply) 
 wrote:

> Consider the output from SHOW DEVICE/FULL below.  Question: why does the 
> "shadow set virtual unit" appear for one of the disks but not the other 
> two?  (For what it's worth, all disks are physically identical.)
> 
> Does it appear if the disk (shadow member) in question does not have a 
> direct connection to the node on which the command is issued?
> 
> Disk DSA510:, device type Generic SCSI disk, is online, mounted, 
> file-oriented
>     device, shareable, available to cluster, error logging is enabled, device
>     supports bitmaps (bitmaps active).
> 

<snip>, physical volumes follow:

>   Volume is also mounted on LEEBIG, MINNIM.
> 
> Disk $110$DKB400:, device type DEC RZ2ED-LS, is online, member of shadow set
>     DSA510:, served to cluster via MSCP Server, error logging is enabled.
> 
>     Error count                    2    Shadow member operation count   
>     3462353
>     Allocation class             110
> 
> Disk $150$DKB400:, device type DEC RZ2ED-LS, is online, member of shadow set
>     DSA510:, shadow set virtual unit, error logging is enabled.
> 
>     Error count                    0    Shadow member operation count    
>     615995
>     Current preferred CPU Id       0    Fastpath                              
>     1
>     Host name               "LEEBIG"    Host type, avail Digital Personal 
>     WorkStation , yes
>     Allocation class             150
> 
> Disk $170$DKB400:, device type DEC RZ2ED-LS, is online, member of shadow set
>     DSA510:, shadow set virtual unit, error logging is enabled.
> 
>     Error count                    0    Shadow member operation count    
>     618930
>     Current preferred CPU Id       0    Fastpath                              
>     1
>     Host name               "MINNIM"    Host type, avail Digital Personal 
>     WorkStation , yes
>     Allocation class             170

Correction: "shadow set virtual unit" appears for the last 2 disks 
listed but not the first.  The first disk is "served to cluster via MSCP 
Server" which implies that there is a direct path from the host to the 
second and third disks but the first is physically connected to another 
system and is visible via MSCP.

-- 
Paul Sture

IBM's Thomas J. Watson predicted a "world market for maybe five computers".
Given the way this whole Cloud thing is going, he might have been extremely
prescient.