Re: VTS allocation performance problems
Hanan, What copy mode are you working with the VTS PtP, Immediate or Deferred? You might consider using deferred copy mode and maybe change the priority the VTS gives the copy operation. It is possible to setup the VTC to prefer specific VTS for I/O. You can also force scratch mounts to the preferred I/O VTS. This is called I/O VTS Preferencing. Gil. On 8/10/05, hanan [EMAIL PROTECTED] wrote: ... I want to be sure that prefernce and elimination options work well with VTS. If it does, maybe the best solution is to assign highest priority to all the devices of the vtc, on which the number of allocated devices is minimal ? Does any one of you know of a similar-logic sources for relevant exits ? I'm addressing the above questions (and coming too) to all of you but especially to you, Norman. We would like to use use different Esoteric names we defined for diferent aspects of logical devices, but we don't know how ? IBM's personal here rejected this possibility and claimed that it can't be done because of SMS behaviour. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
Re: VTS allocation performance problems
1. Transfer rate to the remote location seems to be 30% lower than the rate seen locally. Is this reasonable? Explain, how far your remote site is? do you use channel extenders? 30% lower than normal could be expected. 2. How do we cause a specific allocation to go to the local VTCs (for critial applications) ? what kind of peer-to-peer VTS configuration do you have? Why do you have 4 VTCs remote? You can keep all your VTCs locally and connect to a remote VTS with following settings. You can set your VTCs to preferred I/O (to local VTS) and deferred copy mode. 3. We also use MIA (CA's Multi Image Allocation). Does anyone use MIA's PREFERENCE feature to affect allocation of the virtual tapes, locally or remote (by placing MIA subsys before OAM in IEFSSNxx) ? We do not see a way to make OAM and ACS routines do preferencing I don't think host has any control over where to write, but your VTCs do. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
Re: VTS allocation performance problems
Hi All, and special thanks to Norman I'd like to explain our problem. Our problem has nothing to do with slow allocation. What makes us worried is unpredictable, very low data xfer rates from time to time. Before migration to VTS we used STK/Timberline ESCON devices. Most of the devices had a dedicated escon channel each, so that, once allocation succeeded, the throuput/performence was fantastic. Now we have 4 local VTCs and 4 remote VTCs connected in a P2P VTS. The allocation algorithm for logical devices is not documented in technical literature and even IBM local engineers are not familiar with it. We found an article in MIA books talking about putting OAM first in order. When we tested the preference option we found out that it didn't work and suspected that it occured because ofthe wrong order between the 2 subsystems. The answer we got from CA related to options and capabilities of MIA without mentioning 'VTS' or ordering possibilities. Our major problem today is unpredictable elapse time depending on lucky/bad combinations of allocations. Some backup works that used to finish within an hour, in previous configuration, might take 5 hours today (if 2 concurrent outfiles are allocated on same VTC with 1 or 2 other pre-allocated files). I want to be sure that prefernce and elimination options work well with VTS. If it does, maybe the best solution is to assign highest priority to all the devices of the vtc, on which the number of allocated devices is minimal ? Does any one of you know of a similar-logic sources for relevant exits ? I'm addressing the above questions (and coming too) to all of you but especially to you, Norman. We would like to use use different Esoteric names we defined for diferent aspects of logical devices, but we don't know how ? IBM's personal here rejected this possibility and claimed that it can't be done because of SMS behaviour. Regards, Hanan Hassan Systems - z/OS Technical Support Mehish, 15 Lincoln, 67134 Tel-Aviv, Israel ph: +972-3-5634352, fx: +972-3-5623717 -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
Re: VTS allocation performance problems
Hi All I'm sorry, but I didn't get any response yet, and I wonder for the reason : - May be the question was not well noticed (sent at end of the week) ? - Is the combination of VTS and MIA so rare ? or do all VTS clients use AUTO-SWitch ? We still do have performence problems for specific jobs, compared with their previous behaviour (runnig with STK/Timberline). I'll be thankfull for tips or advices (how to improve the performence) or for checklists of 'undo's. Regards, Hanan Hassan Systems - z/OS Technical Support Mehish, 15 Lincoln, 67134 Tel-Aviv, Israel ph: +972-3-5634352, fx: +972-3-5623717 - Original Message - From: hanan [EMAIL PROTECTED] Newsgroups: bit.listserv.ibm-main To: IBM-MAIN@BAMA.UA.EDU Sent: Thursday, July 28, 2005 7:04 PM Subject: VTS allocation performance problems Hi All, We are operating a VTS in a Peer-to-Peer configuration, and have some questions not addressed by the manuals (as far as we can tell). 1. Transfer rate to the remote location seems to be 30% lower than the rate seen locally. Is this reasonable? 2. How do we cause a specific allocation to go to the local VTCs (for critial applications) ? 3. We also use MIA (CA's Multi Image Allocation). Does anyone use MIA's PREFERENCE feature to affect allocation of the virtual tapes, locally or remote (by placing MIA subsys before OAM in IEFSSNxx) ? We do not see a way to make OAM and ACS routines do preferencing Regards, Hanan Hassan Systems - z/OS Technical Support Mehish, 15 Lincoln, 67134 Tel-Aviv, Israel ph: +972-3-5634352, fx: +972-3-5623717 -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] 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 [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
Re: VTS allocation performance problems
There are many sites that run VTS with Multi Image Allocation. MIA should have nothing to do with performance of the Data transfer. If a device allocates slowly, that could be an opportunity for MIA. If you are in MODE=GROUP, you can adjust the cycle time to be more responsive. I do recommend MODE=DEMAND, unless you have a very large n-way Sysplex. You absolutely can use device Preferencing for MIA managed devices. It works very well. You could use different Esoteric names for the devices at the Remote site. Example: UNIT=REMTAPE. It's easy to create a different EDT for each data center to reference the other one. Other sites have become very sophisticated by coding specific exits to handle remote Devices. Without knowing exactly what you are trying to do, it's hard to help you pick the correct route. I always vote for the simplest way. Could the performance challenge be related to the peer-to-peer hardware? If it worked adequately previous with STK, it should work just as good with the VTS. Again, I think more info is needed. Let me know if you need additional help with MIA. Norman Hollander CA Technology Services -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
VTS allocation performance problems
Hi All, We are operating a VTS in a Peer-to-Peer configuration, and have some questions not addressed by the manuals (as far as we can tell). 1. Transfer rate to the remote location seems to be 30% lower than the rate seen locally. Is this reasonable? 2. How do we cause a specific allocation to go to the local VTCs (for critial applications) ? 3. We also use MIA (CA's Multi Image Allocation). Does anyone use MIA's PREFERENCE feature to affect allocation of the virtual tapes, locally or remote (by placing MIA subsys before OAM in IEFSSNxx) ? We do not see a way to make OAM and ACS routines do preferencing Regards, Hanan Hassan Systems - z/OS Technical Support Mehish, 15 Lincoln, 67134 Tel-Aviv, Israel ph: +972-3-5634352, fx: +972-3-5623717 -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
