IBM s/390 manual 560, 222222

//BACKUP	EXEC PGM=IEBGENER
//SYSPRINT	DD SYSOUT=*
//SYSIN	DD DUMMY
//SYSUT1	DD	DISP=SHR,DSN=SYS1.PROCLIB(JES2)
//SYSUT2	DD	DSN=PROCLIB,DISP=(NEW,KEEP),

//UNIT=560,LABEL=(1,SL),VOL=SER=222222

We submitted the job and the IEF233A mount request was issued by OS/390. The console interaction went like this:

$HASP373	P390T STARTED - INIT 1
IEF244I	P390T - UNABLE TO ALLOCATE 1 UNIT(S)
IEF877E	P390T NEEDS 1 UNIT(S)
FOR SYSUT2
FOR VOLUME 222222
OFFLINE
0560
02 IEF238D	P390T - REPLY DEVICE NAME OR ‘CANCEL’
2,560

IEF503I UNIT 0560 I/O ERROR

IEF234E D 0560

IEF233A M 0560,222222,P390T,,PROCLIB

(at this point, go to the flexescli window and issue the command (flexes> mount 560 /tmp/222222

IEC512I LBL ERR 0560,		,NL,222222,SL,P390T
IEC704A	L 0560,222222,SL,NOCOMP,P390T
03 IEC704A	REPLY ‘VOLSER,OWNER INFORMATION’, ‘M’ OR ‘U’

3,222222

As seen in this interaction, we submitted our job. The tape drive was offline and OS/390 requested that we provide a device. We answered with the device address, 560. We next received a mount request for volume 222222 (taken from our JCL) on unit 560. At this point, we switched to the CLI window (with the flexes prompt) and entered mount 560 /tmp/222222. This file name was quite arbitrary; if you plan to use many emulated tape volumes, you will probably want to create a directory for them (and perhaps a whole file system for them).

OS/390 attempted to read the tape label (using an empty /tmp/222222 file) and received an error. This causes normal recovery processing for tape labels. We entered a volser (222222) in response to message IEC704A, and the job ran correctly. OS/390 rewound and unloaded the “tape” at the end of the job. This logically unmounted the file and made the tape drive logically not ready.

We later read the tape and printed (to SYSPRINT) the tape contents. The process was about the same, except our tape file (/tmp/222222) now had a correct label and was immediately accepted after we entered another flexes> mount 560 /tmp/222222 command.

Server files used by FakeTape are normal files in the server’s file systems. With a little planning—for space and naming—a whole tape library can be emulated using inexpensive server disks. A file (in the server file system) is equivalent to a tape volume. You can compress these files, ftp them, write them on CD-ROMs, and so forth, provided they are restored to their normal form when used again by FakeTape.

FakeTape can automatically recognize and handle data in AWSTAPE and AWSOMA formats, as produced by P/390-related systems. You should be able to exchange such files via ftp, although we did not try this. You can use the FLEX-ES utility initawstape to initialize a file in AWSTAPE format and then write output data to it.

46S/390 PID: ThinkPad Enabled for S/390