Unfortunately, we're still running z/OS 1.7, so IBM will not allow us to open a PMR for this issue. We are a small shop and do not have a lot of tape drives available and are trying to minimize the number of tape drives in use at a time. Two backup tasks are started even though we specify MAXBACKUPTASKS(1) and DUPLEX BACKUP (N). The tasks are backing up different volumes and write concurrently to the drives. It looks like HSM is defaulting to 2 tasks even though we are requesting only 1.
According to the manual: Explanation: MAXBACKUPTASKS(nn) is an optional parameter specifying the maximum number of volume backup tasks DFSMShsm can concurrently process. For nn, substitute a decimal number from 1 to 15 to represent the number of volume backup tasks to be run concurrently. DFSMShsm Defaults: If you do not specify this parameter on any SETSYS command, the DFSMShsm default is two tasks. Explanation: DUPLEX allows DFSMShsm to create two tapes concurrently, the original tape intended to be kept onsite and the alternate tape taken offsite or written to a remote tape library. BACKUP(Y|N) Duplex alternates will or will not be made for backup volumes. If this subparameter is not specified, no change will be made to the current setting for backup. Y specifies that duplexing will occur for backup tape volumes. N specifies that duplexing will not occur for backup tape volumes. DFSMShsm Defaults: If you do not specify DUPLEX and either of its subparameters, DUPLEXING does not occur. -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of O'Brien, David W. (NIH/CIT) [C] Sent: Friday, April 17, 2009 1:58 AM To: IBM-MAIN@bama.ua.edu Subject: Re: DFHSM MAXBACKUPTASKS(1) using 2 drives Robert, No, I don't think I'm confused. The OP wrote that 2 drives were allocated for 1 Backuptask. While I've done what you're suggesting to speed up batch jobs, I'm not sure how or why you would specify Unit=(TAPE,2) for a HSM subtask. Could you elaborate? I take it you are awash with spare tape drives. Dave O'Brien NIH Contractor ________________________________________ From: IBM Mainframe Discussion List [ibm-m...@bama.ua.edu] On Behalf Of Robert A. Rosenberg [hal9...@panix.com] Sent: Thursday, April 16, 2009 11:35 PM To: IBM-MAIN@bama.ua.edu Subject: Re: DFHSM MAXBACKUPTASKS(1) using 2 drives At 15:49 -0400 on 04/16/2009, O'Brien, David W. (NIH/CIT) [C] wrote about Re: DFHSM MAXBACKUPTASKS(1) using 2 drives: >Er Jay, We're talking about tape drives here. > >1 Backup Task should have 1 DASD unit as input and 1 Tape unit as >output. > >The OP specified Duplexing was turned off. > >Dave O'Brien >NIH Contractor I think there is some confusion. MAXBACKUPTASKS(1) means start 1 task. DUPLEX BACKUP(N) means create only 1 Backup Dataset (ie: One DD). DUPLEX BACKUP(Y) would mean to allocate 2 DDs (and thus 2 backup datasets) and write each record to both DDs. The two tape drives allocated is probably due to UNIT=(TAPE,2) being used for the allocate (ie: Allocate 2 drives and switch to the 2nd drive/tape at EOV on the first tape to save time when you rewind/unmount it and need a second tape mounted to continue to backup file create [the 2nd tape is already mounted/ready]). ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
