Yes, but that is the essence of the os390 operating system. It shares resources virtually, to get the best use from them. With sequential devices like tapes, which it is not practical to interrupt, you need to ensure that the virtual demand is not too far out of line with the real resource (number of tape drives). OS390 production lpars are normally tightly controlled, you should not see unexpected demand for tape, and you should be able to achieve this balance for the most part by attention to scheduling of TSM processes that use tapes, so that they occur at times when the demand from non TSM tasks for tapes is low. If best efforts still mean you cannot meet the demand, and you cannot reduce it, then you have to increase the resource, but this applies equally to dedicated TSM systems.
Bill Boyer <[EMAIL PROTECTED]> on 05/22/2002 06:41:08 PM Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] cc: (bcc: John Naylor/HAV/SSE) Subject: Re: yes/no tape question If you have several Z-boxes or LPARS sharing the tape drives...You would have some offline when they are online to other systems. Unless you're in a Sysplex.... This was where we would get bit. The TSM server wasn't on the 'production' LPAR and the operator would vary the drives offline and online to the production LPAR leaving only 1 or 2 drives for TSM. Plus DFSHShsm was on this LPAR...primary and secondary space management took up drives... Even if you have only those physically attached drives defined in HCD,you can end up with tape drive allocation due to other processes and users using the drives. Unless you can dedicate drives and an LPAR/Z-box just to TSM, there's always the possibility of a drive not being available. You get some DFU running a big SAS program using 5-tape drives....the words justifiable homicide comes to mind! :-) Bill Boyer DSS, Inc. "Backup my harddrive...how do I put it in reverse?" - ?? -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED]]On Behalf Of Sam Sheppard Sent: Wednesday, May 22, 2002 12:11 PM To: [EMAIL PROTECTED] Subject: Re: yes/no tape question ---------------------------- Top of message ---------------------------- >>--> 05-22-02 09:06 S.SHEPPARD (SHS) Re: yes/no tape question The situation you describe is easily handled by correctly managing the hardware and software definitions in OS/390 HCD. Drives which are defined on the hardware side but are not in service yet should not be defined to the software side until they are ready for use, at which time they can easily be added on the fly. This prevents the problems you describe with offline devices (reply Device name, Wait, or Cancel). Sam Sheppard San Diego Data Processing Corp. (858)-581-9668 -----------------------------------------------------------------------` ---------------------------- Top of message ---------------------------- >>--> 05-22-02 08:59 ..NETMAIL () Re: yes/no tape question Date: Wed, 22 May 2002 11:56:36 -0400 From: "Bill Boyer" <[EMAIL PROTECTED]> Subject: Re: yes/no tape question for os/390 server people To: [EMAIL PROTECTED] _________________________________Top_of_Message_____________________________ ____ > >Not only the mountlimit for the deviceclass, but how many tape drives are >online versus how many are actually gen'd in the system via HCD. You may >have a string of 8-3590's gen'd, but currently only have 4 physically hooked >up. As far as MVS allocation is aware, these are devices that are just >offline. If TSM needs a tape drive, and there aren't any available, but >there are offline devices you end up with dynamic allocation messages from >TSM (can't remember the ANR* message) and/or the more familar REply Device >name, Wait, or Cancel message to the operator console. Message automation >can take care of some of this, but cancelling a request for a tape drive to >TSM can fail a backup or process. This is probably the thing I hate the most >about TSM on OS/390...you can't tell TSM EXACTLY how many drives are >available. All allocation goes through OS/390. > >Bill Boyer >DSS, Inc. > -----------------------------------------------------------------------` ********************************************************************** The information in this E-Mail is confidential and may be legally privileged. It may not represent the views of Scottish and Southern Energy plc. It is intended solely for the addressees. Access to this E-Mail by anyone else is unauthorised. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. Any unauthorised recipient should advise the sender immediately of the error in transmission. Scottish Hydro-Electric, Southern Electric, SWALEC and S+S are trading names of the Scottish and Southern Energy Group. **********************************************************************
