Hercules V4.00.0 - User Reference Guide

Specifying "COMP=n" means that uncompressed data sent to the client will be compressed. If the data to
be sent to the client is already compressed then the data is sent as is unless the client has indicated that
it does not support that compression algorithm.

9.4 Usage of Shared Devices

To use a device on a remote Hercules instance, instead of specifying a file name on the device state-
ment, an IP address or a DNS name is specified.

9.4.1 Syntax

Descriptive

loc host[ ] [
n]

Diagram

~¬¬¬ ¬¬¬®

ÊÊ¬¬¬ loc ¬¬¬ ¬¬¬
host ¬¬¬¦¬¬¬¬¬¬¬¬¬¬¬¬¬¦¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬Ê

Ê¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬§¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬ÊÍ

9.4.2 Parameter

loc_devnum

This specifies the device address on the local Hercules instance.

devtype x

This is the device type.

host

This specifies the host name or the IP address of the system where the Shared De-
vice Server is running.

port

The port number on which the Shared Device Server is listening. If the port number
is omitted then the default port (3990) is used.

rem_devnum

This is the device address of the device on the remote Hercules instance. If the re-
mote device address is omitted then the default is the current device number on the
local system.

COMP=n

This keyword requests that the data has to be transferred compressed between the
client and the server. The argument n specifies the compression level (1-9). A
value closer to 1 means less compression but also less processor time to perform
the compression. A value closer to 9 means the data is compressed more but also
more processor time is required to compress the data.

9.4.3 Examples

Example 1:

There is a shared device server on the local host listening on port 3990 and we want to use its 0100
device as our 0100 device. The device statement will look like this:

0100 3390 localhost:3990:0100

Because the default port number is actually 3990 and the default remote device address is the same as
the local device number the above statement (providing we do not have actually a file named 'localhost' )
could be shortened as follows:

0100 3390 localhost

Example 2:

Device sharing can also be split between multiple instances. For example, suppose the following device
definitions and system parameter for instance A:

SHRDPORT 3990

0100 3390 localhost:3991

0101 3390 mvscat.dasd

And for instance B we have the following device definitions and system parameter:

SHRDPORT 3991

0100 3390 mvsres.dasd

0101 3390 localhost

In this case each instance acts as both a client and a server. Both instances of Hercules are running on
the same machine.

The above examples may be clearer if we specify also all the default values. To show this the same con-
figuration is used but in this case the Hercules instances are running on separate physical machines: