passed to a device I/O thread to be completed asynchronously instead.
SYNCIO is the default for CKD devices. SYNCIO statistics may be displayed via
the Hercules SYNCIO console command. SYNCIO may be abbreviated as SYIO.
Note: If you plan on using SYNCIO with Linux/390 and/or zLinux you might also
want to take a look at the IODELAY system parameter as well.
READONLY
READONLY returns “write inhibited” sense when a write is attempted. Note that not
all the sense bits may be set absolutely correctly.
FAKEWRITE
FAKEWRITE is a workaround for the READONLY sense problem that was men-
tioned above. In these cases the disk is not intended to be updated (e.g. MVS up-
dates the DSCB last referenced field for a readonly file) and any writes appear to
be successful even though nothing is actually written.
type
Specifies the type of control unit to which this device is attached. The use of this
parameter does not necessarily imply that all functions of the specified control unit
are emulated. The purpose is to force a particular control unit type to be indicated
in the data returned by SENSE ID and similar CCW's.
Normally the default value is appropriate and this parameter need not to be speci-
fied. Additional to the table below the following values may be specified: 3990-3
and 3990-6. The default value depends on the device type as shown in table below.
ipname
This is the host name or IP address of the system where the Hercules shared de-
vice server is running.
port
This is the port number the shared device server is listening on. If omitted the de-
fault is 3990.
devnum
Devnum specifies the device number on the shared device server. If omitted 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). Values
closer to 1 mean less compression but also less processor time to perform the
compression. Values closer to 9 mean the data is compressed more but also more
processor time is required to compress the data.
Two other options LAZYWRITE and FULLTRACKIO have been deprecated. They are still accepted to
support compatibility with older configuration files but do actually nothing. It is strongly recommended to
remove these statements from the configuration file.
The following table shows the default Control Unit types depending on on the device type:
Device Type
Default CU Type
2311
2841
2314
2314
3330, 3340, 3350, 3375, 3380
3880
