At last a definitive answer! Glenn, why would SETSYS TAPEDSORDER(RECALL(FBID)) be temporary? From your description I can't see any reason NOT to make it the operating norm. Thank You, Dave O'Brien NIH Contractor ________________________________________ From: Glenn Wilcock [[email protected]] Sent: Friday, October 12, 2012 11:20 AM To: [email protected] Subject: Re: DFHSM Recalls and Tape
In both a CRQ and nonCRQ environment, HSM will process all of the queued requests from a mounted tape. But, there are some important differences. In a nonCRQ environment, each HSM host has it's own queue. So, each host will only process the queued requests on it's own queue. This requires each host to mount/unmount the same tape. Also, the recall queue has to be sequentially scanned to find the next recall on the same tape. This may require alot of processing for large queues. In a CRQ environment, there is a shared queue, so the first host that mounts the tape will process ALL recalls in the HSMplex that require that tape. (Truly a single tape mount). Also, within the CRQ, a unique prioritized LIST is maintained for the recalls queued for each tape, so the next recall can be found with a single Request to the Queue, as opposed to having to scan the queue sequentially. When queuing thousands of recalls which will come from the same tapes, I recommend temporarily using SETSYS TAPEDSORDER(RECALL(FBID)). This will recall the data sets on the same tape in FBID order, which will give better performance since you will be driving many recalls from the same tape. For random recall activity, I would recommend RECALL(PRIORITY), which will process WAIT requests before NOWAIT type requests. Glenn Wilcock DFSMShsm Architect ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
