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Conference star::wizards

Title:	"ASK THE WIZARDS"

Moderator:	QUARK::LIONEL

Created:	Mon Oct 30 1995
Last Modified:	Mon May 12 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	1857
Total number of notes:	3728

1527.0. "Open: projection of growth path?" by STAR::JKEENAN () Tue Feb 11 1997 08:18

Date: Mon, 10 Feb 1997 18:40:08 -0500
Message-Id: <[email protected]>
From: "VMS001::WWW"@vms001.das-x.dec.com (10-Feb-1997 1840)
To: [email protected], [email protected], [email protected]
Subject: Ask the Wizard: '[email protected]'

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Name: Peter Grewe
Email Address: [email protected]
CPU Architecture: Alpha
Version: v 6.2
Questions: 

We have three Alpha 1000A's SCSI clustered into a dual HSZ40 Raid.   Currently only three hosts are supported on SCSI cluster, or that's what we are only aware of.

We would like to project our growth path with additional Alpha's and SCSI clustering.  However, will there be support for more than 3 hosts in SCSI cluster??P

T.R Title User Personal
Name Date Lines

1527.1 Three; Consider Additional/Alternative Paths XDELTA::HOFFMAN Steve, OpenVMS Engineering Tue Feb 11 1997 10:08 38

T.R	Title	User	Personal Name	Date	Lines
1527.1	Three; Consider Additional/Alternative Paths	XDELTA::HOFFMAN	Steve, OpenVMS Engineering	`Tue Feb 11 1997 10:08`	38
	:We have three Alpha 1000A's SCSI clustered into a dual HSZ40 Raid. :Currently only three hosts are supported on SCSI cluster, or that's :what we are only aware of. : :We would like to project our growth path with additional Alpha's and :SCSI clustering. There are multiple transports available for use in a VMScluster, SCSI, FDDI, NI, CI, MC, and DSSI. SCSI itself is a storage-only interconnect, one must use some other connections -- often NI or FDDI -- as the communications path. When adding systems and depending on the communications traffic, I would tend to start configuring SCSI into "triangles" or similar. Triangle: a three-host configuration, where each host has two SCSI busses, each directly connected to one of the other two hosts. I would configure multiple hosts with multiple SCSI busses each, and all hosts are not configured on a single (shared) bus. Placing all hosts on a single SCSI bus can lead the complete configuration becoming unavailable should the shared SCSI bus become disconnected for any reason. I would also start adding faster communications links, such as FDDI and MC. Depending on the distances involved, CI should also be considered. : However, will there be support for more than 3 hosts : in SCSI cluster??P The maximum number of systems that can be connected to a single SCSI bus -- per the V7.1 VMScluster SPD -- is three. I am aware of no announced support for configurations with more than three hosts.

:We have three Alpha 1000A's SCSI clustered into a dual HSZ40 Raid.
:Currently only three hosts are supported on SCSI cluster, or that's
:what we are only aware of.
:
:We would like to project our growth path with additional Alpha's and
:SCSI clustering. 

   There are multiple transports available for use in a VMScluster,
   SCSI, FDDI, NI, CI, MC, and DSSI.

   SCSI itself is a storage-only interconnect, one must use some
   other connections -- often NI or FDDI -- as the communications
   path.

   When adding systems and depending on the communications traffic,
   I would tend to start configuring SCSI into "triangles" or similar.
   Triangle: a three-host configuration, where each host has two SCSI
   busses, each directly connected to one of the other two hosts.

   I would configure multiple hosts with multiple SCSI busses each,
   and all hosts are not configured on a single (shared) bus.  Placing
   all hosts on a single SCSI bus can lead the complete configuration
   becoming unavailable should the shared SCSI bus become disconnected
   for any reason.

   I would also start adding faster communications links, such as FDDI
   and MC.  Depending on the distances involved, CI should also be
   considered.

: However, will there be support for more than 3 hosts
: in SCSI cluster??P

   The maximum number of systems that can be connected to a single
   SCSI bus -- per the V7.1 VMScluster SPD -- is three.  I am aware
   of no announced support for configurations with more than three
   hosts.