We use a Sun/STK VTS (shared with z/OS). Scratch mounts are nearly instantaneous (unless z/OS isn't responding due to high batch workloads).
Recalls times vary depending upon whether the virtual tape was in cache, or on 'backing store' (i.e. offloaded to real physical tapes within the VTS robotics). If the recall is in cache, the mount is also near-instantaneous. But recalls of tapes on backing store can take a long time, depending on how busy the real tape drives are (many z/OS systems here can place a stress load on the VTS), how full cache is (the VTS may have to offload some virtual tapes to real tapes to make room for your recalled file), and other factors. I suspect that those same effects will be pretty consistent across all brands of VTS manufacturers that use cache for virtual tapes, and real tapes for offloading as backing store. Do you have any commands to display cache utilization, virtual and real tape drive utilization, and real tape 'fragmentation'? It might be time to "merge/purge" backing tapes, running a vendor provided utility to copy unexpired virtual tapes from fragmented real tapes onto fresh real tapes, more fully filling the new real tapes, and freeing up whole real tapes for re-use. Mike Walter Hewitt Associates "Suleiman Shahin" <s_s_sha...@hotmail.com> Sent by: "The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU> 05/10/2009 06:55 PM Please respond to "The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU> To IBMVM@LISTSERV.UARK.EDU cc Subject Re: VTS issues Mainly for recall of existing files. But also mount times for scratches can take 3 minutes. Thanks. Suleiman Shahin ---------------------------------------- > Date: Sun, 10 May 2009 17:40:12 -0500 > From: mike.wal...@hewitt.com > Subject: Re: VTS issues > To: IBMVM@LISTSERV.UARK.EDU > > Mount times for scratch tapes or recall of existing files? > > Mike Walter > _________________________________________________________________ Hotmail® has a new way to see what's up with your friends. http://windowslive.com/Tutorial/Hotmail/WhatsNew?ocid=TXT_TAGLM_WL_HM_Tutorial_WhatsNew1_052009 The information contained in this e-mail and any accompanying documents may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient of this message, or if this message has been addressed to you in error, please immediately alert the sender by reply e-mail and then delete this message, including any attachments. Any dissemination, distribution or other use of the contents of this message by anyone other than the intended recipient is strictly prohibited. All messages sent to and from this e-mail address may be monitored as permitted by applicable law and regulations to ensure compliance with our internal policies and to protect our business. E-mails are not secure and cannot be guaranteed to be error free as they can be intercepted, amended, lost or destroyed, or contain viruses. You are deemed to have accepted these risks if you communicate with us by e-mail.
