The DeviceShare utility allows a node to share its local tape devices with other
nodes using TCP/IP. By providing such access, DeviceShare expands the usefulness,
connectivity and availability of all your backup devices.
Figure 1 illustrates a simple network environment. Node A is serving its local
tape device, /dev/nrmt0l, on the network. Node B and Node C access the tape via
their local pseudo device, /dev/devshr1. The remote tape device appears to be local
for Node B and Node C.
Cross-Platform Support:
DeviceShare for Digital UNIX is cross-platform compatible with V2.2-000 for OpenVMS.
You can access OpenVMS tapes using the client for Digital UNIX and vice versa.
Network Operation:
In a TCP/IP network, you can share a tape device to any node in your network. You
may also restrict access to certain specified nodes. For network operations, this
software is licensed for Server and/or Client use. The Server license permits to
serve tape devices throughout the network. The Client license permits the use of
special drivers which provide local access to the remote tape. To make a device
accessible to other nodes in your network, you must install and license the Server
system on the serving node. A server node is the system which has physical access
to the device. The System Administrator must specifically enable a device for access
(i.e. serve the tape).
To gain access to the device, you must install and license the Client system on
the client node. You would then issue the DeviceShare command to allocate the device.
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.
You can access the remote tape via this pseudo device once its allocated.
All I/O operations to the pseudo device are sent to the remote server node where
the physical tape exists using TCP/IP. The I/O operations are executed on the remote
tape device and the result is sent back to the client.
The System Administrator can de-allocate the remote tape device by issuing the de-allocate
command. This marks the remote tape as available allowing other DeviceShare clients
to use the tape.
Include and Exclude:
The System Administrator can specify which nodes are allowed access to a served
tape by using the include/exclude feature.
Generic Naming:
DeviceShare provides a generic naming feature by which a System Administrator can
associate alias names to served devices. For example, if a tape drive on Node A
is known as /dev/nrmt0l and supports 4MM DAT tapes, the System Administrator might
assign it the alias 4MMDAT. This is particularly useful if multiple 4MM DAT tape
drives were on the same node. By naming all the 4MM DAT tape drives, 4MMDAT, a generic
allocate command for the device 4MMDAT will return access to the first available
drive. This generic naming facility allows you to provide easy to remember names
for various tape devices without requiring users to actually know the physical device
name.
Utility Programs:
Included utility programs are used to maintain the served tapes. The server has
a utility program that allows you to see the status of served tapes and other information
such as the Process ID of the DeviceShare client on the remote node. The client
has a monitor utility program that lets you view the status of the tapes accessed
remotely.
Network Restart:
An automatic network reconnection facility is provided. In the event your network
is temporarily disrupted, DeviceShare will automatically attempt to reconnect between
the Server and Client systems. 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 DeviceShare is able to reconnect and reallocate the device,
your backup will continue with no loss of data or failure assuming that the source
and target devices remain in a consistent state.
Logging:
Useful information is logged to a file which can be specified by the user. Information
logged on the server node includes connection requests made by remote nodes for
tape devices, successful allocation of tape devices to remote nodes, and allocation
failures. The client node logs information related to connections and allocations
of devices on remote server nodes. All warning and error messages are also logged.
Device Locking:
You can lock remote tape devices for exclusive access. All processes, whether local
or remote, will be denied access to the tape drive if it is locked. Optionally,
the tape device can be allocated without a lock. The first I/O operation on the
tape locks the device. This is useful if you are not going to use the tape immediately
and would like to allow other processes to access the tape in the meantime.
Minimum Hardware Supported:
This software is warranted for use with all Digital supported busses, used in conjunction
with a Digital-supplied device driver.
DeviceShare also works with all third-party controllers and tape drives that use
unmodified, Digital tape device drivers.
Prerequisite Software:
Any Alpha processor, using Digital UNIX 4.0 or later. Other UNIX platforms are being
considered.
When used for network operation, TCP/IP must be setup. The nroff product must also
be installed on the system for using the online help which is provided in the form
of man pages. The nroff product is part of the "Text Processing: Doc. Preparation
Tools" subset provided with Digital UNIX.
Software Installation:
Installation of this software product is subject to the terms of the ASCI Standard
Software Product License Agreement. DeviceShare can be installed manually by the
System Administrator. An optional installation script is provided to automate the
installation and setup procedures.
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 license supports both the server and client functions. The Server
license supports the tape server functions on a single node. The Client license
supports remote tape access from a remote node.
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 magnetic distribution of software, a Manual, a Software
Product License Agreement, a Software Product Description, and a ASCI Product Authorization
Key.
DEV-300-LIC-Full-Function License
DEV-301-LIC-Client License
DEV-302-LIC-Server License
