The DeviceShare utility allows a member of a DECnet network or a VMScluster to share
its local tape and disk devices with other nodes. By providing such access, the
usefulness, connectivity, and availability of all your mass storage devices is expanded.
Network Operation:
Figure 1: A mixed DECnet/VMScluster Configuration
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In a DECnet and/or TCP-IP network, DeviceShare allows you to share a tape and/or
disk device to any node in your network. You may also restrict access to certain
specified nodes. The Server license permits the ability to serve devices throughout
the network. The Client license permits the use of special device drivers which
provide local access to the remote tape and disk.
To make a device accessible to other nodes in your network, you must install and
license the system on the serving node. A server node is the system which has physical
access to the device. This software provides both automatic and manual device serving
capabilities. In the automatic mode, DeviceShare provides serving of all tape and/or
disk devices. In the manual mode, the System Manager must specifically enable a
device for access. Regardless of mode, DeviceShare does provide the ability to either
INCLUDE or EXCLUDE nodes in your network from use. To gain access to the device,
you must install and license the DeviceShare system on the client node. A utility
command permits you to obtain information concerning those devices which are shareable
on the Server node as well as those remote devices in use on a remote node. To actually
use them, you issue the ALLOCATE command. This command determines whether you can
gain access to the device (i.e. proper security, device not in use), and, if so,
creates a special pseudo device for your local use. DeviceShare does support network
data compression and time-based multiplexing of messages across the network for
maximum efficiency. The ALLOCATE command also provides a generic naming feature
by which a System Manager can associate alias names to served devices. For example,
if a tape drive on VAXA is known as $1$MUA0: and supports 6250-bpi, the System Manager
might assign it the alias 6250bpi. This is particularly useful if multiple 6250
tape drives were on the same node. By naming all the 6250 tape drives, 6250bpi,
a generic ALLOCATE command will return access to the first available drive. This
generic naming facility allows you to provide easy to remember names for various
disk and tape devices without requiring users to actually know the physical device
name.
Shareable access to a disk device is supported. If the disk is mounted as a Files-11
device, then transparent file access is permitted. The Files-11 device may be either
a single volume or a multiple device volume set. The ALLOCATE command for a remotely
mounted disk causes the device to also become locally mounted. While files may be
opened for read and/or write access, DeviceShare will not permit multiple simultaneous
write access to a single file due to locking/consistency considerations. However
you have the ability to exclusively gain access to a remote disk, in which case,
complete file sharing is provided. Three (3) security levels for remote client user
access to a shared disk: Authentication, Server and Client. Authentication requires
the remote client user to verify his account and password on the server system prior
to shared disk access. Server security requires the remote client user to have an
account on the server system, and DeviceShare will apply the server's privileges
on shared disk access. Client security is similar to server security except the
remote client user's privileges will be used when accessing a shared disk.
A built in network data compression algorithm which, depending on your data, can
increase the effective utilization of your served network device. Support for Network
Throttling, which permits a node to constrain the amount of network bandwidth it
can consume, is also supported.
An automatic network reconnection facility is provided with the software. In the
event your network is temporarily disrupted, DeviceShare will automatically attempt
to reconnect between the Server and Client systems. This reconnection appears to
the system as a mount verification. Mount verification messages will appear when
the connection is broken, regained or aborted. Just as with mount verification,
the reconnection interval is user controlled and the default time period is five
(5) minutes. The automatic network reconnection facility is particularly useful
when you are backing up a large disk to tape and the backup is expected to take
several hours. If the software is able to reconnect, and the source and target devices
remain in a consistent state, your backup will continue with no loss of data or
failure.
DeviceShare provides remote users with the ability to determine which remote devices
are currently in use and/or served to their node.
Figure 1 illustrates a mixed cluster/network environment. Node A and B have cluster
access to the high-speed tape and disk devices through the HSC. Nodes C and D are
network members. Node C has a local SCSI disk and Node D has both several SCSI disks
and a CDROM device. By installing this software on all the nodes in this configuration,
Node A, B and C gain access to the CDROM device on Node D, and Nodes C and D gain
access to the high-speed tape and disk drives on the VMScluster. This illustration
also depicts a centralized backup approach, where Nodes A and/or B can backup Nodes
C and D's disk drives onto a common tape media.
Operator Message Handling:
DeviceShare automatically and transparently handles OPCOM requests related to remotely
served devices. For example, if Node A is serving a tape (or disk) to Node B, and
Node B needs to request a specific tape, the handling of that request is transparent
to Node B. Node B's OPCOM request is automatically routed to the operator on Node
A. Any operator replies are also re-routed back to Node B. In addition, a special
OPCOM command which allows your DCL procedures to request special device handling
from an operator has been implemented. The operator's reply can be placed in a DCL
symbol of your choosing for later programmatic interpretation.
Cluster Operation:
Figure 2: Transparent Operator Services
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To make a tape device accessible to other nodes in a cluster, you must install the
software on the serving node. A server node is the system that has physical access
to the tape device. A client node gains access to the tape device through a server
system. Figure 2 depicts a mixed CI/NI VMScluster. In this configuration the magnetic-tape
drives on the HSC are available only to Nodes A and B. Only Node B can access the
digital audiotape (DAT) drive, and Node C alone can use the TK50. Node D has no
tape drives at all. Installing DeviceShare on Node B permits every node in the cluster
to access the magtape and DAT drives. Likewise, installing on node C allows full-cluster
access to the TK50. Loading the software on Node A also provides cluster access
to the magtapes in the event of a loss of Node B. After installing on Nodes A, B,
and C, Node D gains access to all the tape devices in the cluster. Cluster access
is both quick and transparent since the TMSCP protocol is used, and all tape devices
(regardless of I/O bus) are supported. Once a tape device is TMSCP served it will
appear on all other nodes in the cluster automatically.
Minimum Hardware Supported:
This product requires a valid OpenVMS configuration and supports the entire family
of VAX and Alpha AXP processors. This software is warranted for use with all Digital
supported busses, used in conjunction with a Digital-supplied device driver.
This software also works with all third-party controllers and disk/tape drives that
use unmodified, Digital disk/tape-device drivers.
Prerequisite Software:
Any VAX processor, using VMS Version 5.5-2 or later and any Alpha processor using
OpenVMS Version 6.1 or later.
When used for network operation, DECnet and/or TCP-IP are supported. If you plan
on using DECnet then a DECnet End-node or Full-function license is required. Currently,
TGV's Mulinet, Process Software's TCPware and Digital's TCP-IP Services for OpenVMS
are supported. DeviceShare automatically detects the appropriate vendor's TCP product
in use. When used for cluster operation, a VMScluster environment is required. If
you are running OpenVMS VAX V5.5 (or later) or OpenVMS Alpha V1.5 (or later) you
cannot run DeviceShare's TMSCP cluster software and Digital's TMSCP server at the
same time. This restriction does not apply to DeviceShare's network services.
Warranty Information:
This software is sold through ASCI's Software Product License Agreement which warrants
the product for ninety (90) days from the date of purchase. Warranty services include
technical assistance, remedial telephone support and product upgrades.
Maintenance Information:
After the initial product warranty expires, ASCI offers an annual customer support
plan. This includes technical assistance, remedial telephone support, product upgrades,
and enhancements, as they become available. The annual customer support plan is
separately priced.
Ordering Information:
The Full-Function Server license supports both disk and tape server and client functions
on a single node. The Full- Function Client license supports remote disk and tape
access from a remote node. The Tape-Only Server license supports only tape server
and client functions on a single node. The Disk-Only Server license supports only
disk server and client functions on a single node.
ASCI honors requests for other magnetic media for a minimal charge, but you must
indicate these in your letter and/or purchase order. The current prices are available
upon request. Multi-CPU and Educational Institutions discounts are available.
This software is licensed using Digital's License Management Facility (LMF). A Product
Authorization Key (PAK) is required for each system prior to product installation
and execution.
DeviceShare consists of a CD-ROM distribution of software (1), Users' Manual (1),
Software Product License Agreement, Software Product Description, and Warranty Registration
Certificate.
DEV-200-LIC-Full-Function Server License and Distribution Media
DEV-201-LIC-Client License
DEV-202-LIC-Tape Only Server License and Distribution Media
DEV-203-LIC-Disk Only Server License and Distribution Media
AD-200-DEV-GS-Getting Started Manual
AD-200-DEV-GO-Operations Manual
