BDAM vs VSAM
In to days Z/OS environment is BDAM faster than VSAM. I understand that IBM does not recommend the use of BDAM, however for those installations that are heavy Assembler and continue to use BDAM has there been any bench marks for the use of BDAM ? The I/OS Subsystem and Access methods have all improved since there inception. So I'm wondering why some mainframe software providers continue to choose BDAM over VSAM. Paul D'Angelo Enterprise System Software Find success and happiness with drug and alcohol rehabilitation. Click now. http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTJWRV9vkx34r8m5NY4xDiqgt4pCLwxfyF16OwZqMfkdNtKnsfJ1mQ/ -- 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
Re: BDAM vs VSAM
esst...@juno.com wrote: In to days Z/OS environment is BDAM faster than VSAM. I understand that IBM does not recommend the use of BDAM, however for those installations that are heavy Assembler and continue to use BDAM has there been any bench marks for the use of BDAM ? The I/OS Subsystem and Access methods have all improved since there inception. So I'm wondering why some mainframe software providers continue to choose BDAM over VSAM. Can you provide a URL that points to an "official" IBM admonishment against the use of BDAM? VSAM does a lot more than BDAM: e.g., LINEAR data sets, EAV cylinder-managed placement, faster I/O rates due to zHPF (FCX) channel programs, etc. But, if BDAM meets your needs, why not use it? -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 edja...@phoenixsoftware.com http://www.phoenixsoftware.com/ -- 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
Re: BDAM vs VSAM
Edward Jaffe Wrote >Can you provide a URL that points to an "official" IBM admonishment >against the use of BDAM? I dont know of any URL taht officialy admonishmes BDAM. They prefer VSAM over BDAM, yet I cannot locate any benchmarks for the use of BDAM. Make the most out of every dollar. Click here to find websites and services to help invest wisely. http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTFOGejikhNOQuwQrURauNsXzQGvSWhBPoyTFKsdKLabrwu2EeDOc4/ -- 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
Re: BDAM vs VSAM
Ed Jaffe wrote VSAM does a lot more than BDAM: e.g., LINEAR data sets, EAV cylinder-managed placement, faster I/O rates due to zHPF (FCX) channel programs, etc. But, if BDAM meets your needs, why not use it? I guess I would ask this another way; When would BDAM be justified over VSAM ? Beauty School Programs - Get the career you've always wanted. Click Now. http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTOtxd5jVig3ebWGWDLMkl5slHWJtxMgeTDP0Ifi2i7oQUXWasKQS0/ -- 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
Re: BDAM vs VSAM
BDAM is probably justified over VSAM mainly when you're maintaining something that's already BDAM. Cheers, Martin Martin Packer Performance Consultant IBM United Kingdom Ltd +44-20-8832-5167 +44-7802-245-584 email: martin_pac...@uk.ibm.com Twitter ID: MartinPacker "They're figuring out that collaboration isn't a productivity hit, it makes them smarter." Sam Palmisano on BlogCentral, 26 November 2008 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- 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
Re: BDAM vs VSAM
> -Original Message- > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On > Behalf Of esst...@juno.com > Sent: Saturday, April 11, 2009 10:35 AM > To: IBM-MAIN@bama.ua.edu > Subject: BDAM vs VSAM > > In today's Z/OS environment is BDAM faster than VSAM. I understand that > IBM does not recommend the use of BDAM, however for those installations > that are heavy Assembler and continue to use BDAM has there been any bench > marks for the use of BDAM ? > > The I/OS Subsystem and Access methods have all improved since there > inception. So I'm wondering why some mainframe software providers continue > to choose BDAM over VSAM. The main reason to choose VSAM (RRDS) would be the limitations of BDAM. BDAM files are limited by various restrictions that VSAM does not have (maximum number of volumes and lack of automatic buffering support come to mind). The main reasons to use BDAM would be simplicity of coding and file definition and the shorter I/O code path, which costs less CPU than equivalent VSAM access. Having participated in several BDAM to VSAM RRDS conversions, I can tell you that the conversion is not without some pain. Much more coding and control structures are required to use VSAM RRDS, and in multitasking or multi-region shared file environments, CI-locking for updates must be expected by read-only (sub)tasks, with appropriate queuing and retry paths. The up side of VSAM RRDS is that you can use BLSR buffering (or today, perhaps better to use SMB, system-managed buffering) to improve performance. The most recent conversion I did gained a substantial speed benefit from massive BLSR buffering (we buffered most or all of the active blocks), since most of the I/O requests were Reads. There was increased CPU consumption due to the BLSR overhead, but this was offset by substantially reduced I/O waits for Reads, thus improving response time a lot. Conversion is not cheap, so the benefits have to be weighed carefully against the cost of conversion in time and training and manpower and maintenance. The ISV software or home-grown application complexity has to be analyzed with multiple criteria to determine if the added complexity of VSAM is worth the effort. Don't forget to include quality assurance parallel operation time and manpower to confirm that the new VSAM version produces the exact same results as the BDAM version. One-to-one comparisons of performance are difficult at best, but the coding simplicity and shorter I/O path length of BDAM can be important differences. There is no doubt in my mind that the VSAM code path length is much longer than BDAM's, but the benefits to be gained from VSAM's enhanced capabilities can also be a deciding factor. As usual, YMMV. It depends greatly on the individual application. HTH Peter This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. -- 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
Re: BDAM vs VSAM
Musing far less CPU time. And a LOT of people find it easier to use than VSAM. It's good stuff, but also easily misused. esst...@juno.com wrote: In to days Z/OS environment is BDAM faster than VSAM. I understand that IBM does not recommend the use of BDAM, however for those installations that are heavy Assembler and continue to use BDAM has there been any bench marks for the use of BDAM ? The I/OS Subsystem and Access methods have all improved since there inception. So I'm wondering why some mainframe software providers continue to choose BDAM over VSAM. Paul D'Angelo Enterprise System Software Find success and happiness with drug and alcohol rehabilitation. Click now. http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTJWRV9vkx34r8m5NY4xDiqgt4pCLwxfyF16OwZqMfkdNtKnsfJ1mQ/ -- 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 -- Rick -- Remember that if you’re not the lead dog, the view never changes. -- 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
Re: BDAM vs VSAM
esst...@juno.com wrote: Edward Jaffe Wrote Can you provide a URL that points to an "official" IBM admonishment against the use of BDAM? I dont know of any URL taht officialy admonishmes BDAM. Without any admonishment against the use of a particular access method, why would one question its use? I do recall IBM stating that ISAM was replaced with VSAM. But, I honestly don't recall any similar "official" statement for BDAM. They prefer VSAM over BDAM, Who is "they"? IBM? A URL supporting this assertion would be really handy right about now... yet I cannot locate any benchmarks for the use of BDAM. Why single out BDAM? Are there published benchmarks comparing other access methods to VSAM? Or to each other? -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 edja...@phoenixsoftware.com http://www.phoenixsoftware.com/ -- 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
Re: BDAM vs VSAM
BDAM has many merits; and old men in this business, I among them, once used it heavily and to advantage. It also has many deficiencies that reflect its age: They could have been avoided it it had been judged important to do so, but it was not. One such, at one time much discussed, BDAM weakness---IBM eliminated it in the design of VSAM---is that DASD [or, now, crypto-DASD] space must be allocated for every conceptually possible key value: key specifications determine DASD space requirements in a very simplistic way indeed. As others have already suggested, there are really two, separable and desirably separated, questions here: 1) Should an existing BDAM-based system necessarily be reimplemented in VSAM? 2) Should any system now be implemented ab initio in BDAM? My answers would be no to the first and yes to the second. John Gilmore Ashland, MA 01721-1817 USA _ Rediscover Hotmail®: Get quick friend updates right in your inbox. http://windowslive.com/RediscoverHotmail?ocid=TXT_TAGLM_WL_HM_Rediscover_Updates1_042009 -- 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
Re: BDAM vs VSAm
The answers to my two questions should of course have been no and no, not no and yes. John Gilmore Ashland, MA 01721-1817 USA _ Rediscover Hotmail®: Get quick friend updates right in your inbox. http://windowslive.com/RediscoverHotmail?ocid=TXT_TAGLM_WL_HM_Rediscover_Updates1_042009 -- 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
Re: BDAM vs VSAM
>Date:Sat, 11 Apr 2009 12:41:10 -0400 >From:"Farley, Peter x23353" >Subject: Re: BDAM vs VSAM >One-to-one comparisons of performance are difficult at best, but the >coding simplicity and shorter I/O path length of BDAM can be important >differences. There is no doubt in my mind that the VSAM code path >length is much longer than BDAM's, but the benefits to be gained from >VSAM's enhanced capabilities can also be a deciding factor. This does not match my experience at all. BDAM builds the CCW string dynamically on every READ macro. The CCW string is then re-built as it is translated Virtual to Real by EXCP. Decades ago VSAM RRDS used much less CPU time per request than BDAM. I would be very surprised it that were not still true, as I doubt BDAM has changed much since MVT. I agree VSAM has changed a lot though, and your comments on the much better buffering capability in VSAM are right on. I doubt that it uses more CPU per I/O than BDAM though. Maybe we need a benchmark after all. Tom Russell "Stay calm. Be brave. Wait for the signs." -- Jasper FriendlyBear "... and remember to leave good news alone." -- Gracie HeavyHand -- 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
Re: BDAM vs VSAM
Tom Russell wrote: This does not match my experience at all. BDAM builds the CCW string dynamically on every READ macro. The CCW string is then re-built as it is translated Virtual to Real by EXCP. Decades ago VSAM RRDS used much less CPU time per request than BDAM. I would be very surprised it that were not still true, as I doubt BDAM has changed much since MVT. I was under the impression that the "traditional" (i.e., pre-VSAM) access methods were updated so they now use Format-1 CCWs and EXCPVR. Was BSAM left behind when that conversion occurred? -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 edja...@phoenixsoftware.com http://www.phoenixsoftware.com/ -- 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
Re: BDAM vs VSAM
I don't know if BDAM was updated to use Format-1 CCWs, but IIRC, BDAM went Class-C on maintenance before the Format-1 CCW existed. This could be considered a definite drawback for any new application considering its use. Edward Jaffe wrote: Tom Russell wrote: This does not match my experience at all. BDAM builds the CCW string dynamically on every READ macro. The CCW string is then re-built as it is translated Virtual to Real by EXCP. Decades ago VSAM RRDS used much less CPU time per request than BDAM. I would be very surprised it that were not still true, as I doubt BDAM has changed much since MVT. I was under the impression that the "traditional" (i.e., pre-VSAM) access methods were updated so they now use Format-1 CCWs and EXCPVR. Was BSAM left behind when that conversion occurred? -- Rick -- Remember that if you’re not the lead dog, the view never changes. -- 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
Re: BDAM vs VSAM
On Mon, 13 Apr 2009 14:44:23 -0500, Rick Fochtman wrote: >... IIRC, BDAM went Class-C on maintenance before the Format-1 >CCW existed. ... Ok. I have a faulty memory. Please 'splain me again "Class-C". I vaguely remember back when IBM was going OCO that they came up with some support classes that I think of as Class-A the operating system code maybe? Class-B fully supported Program Products Class-C SE-supported Class-D unsupported FDPs I don't remember any access method code being anything but Class-A so I suspect that is not what what you were refering to (or that my faulty memory has totally broken down - always a reaonable possibility). Pat O'Keefe -- 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
Re: BDAM vs VSAM
IIRC, CLASS-C Maintenance meant that old faults would be repaired but that there would be no further updates to account for hardware or OS upgrades. Patrick O'Keefe wrote: On Mon, 13 Apr 2009 14:44:23 -0500, Rick Fochtman wrote: ... IIRC, BDAM went Class-C on maintenance before the Format-1 CCW existed. ... Ok. I have a faulty memory. Please 'splain me again "Class-C". I vaguely remember back when IBM was going OCO that they came up with some support classes that I think of as Class-A the operating system code maybe? Class-B fully supported Program Products Class-C SE-supported Class-D unsupported FDPs I don't remember any access method code being anything but Class-A so I suspect that is not what what you were refering to (or that my faulty memory has totally broken down - always a reaonable possibility). Pat O'Keefe -- 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 -- Rick -- Remember that if you're not the lead dog, the view never changes. -- 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
Re: BDAM vs VSAM
On Mon, 13 Apr 2009, Rick Fochtman wrote: > IIRC, CLASS-C Maintenance meant that old faults would be repaired but > that there would be no further updates to account for hardware or OS > upgrades. > However, given the "3390 DASD architecture forever" mantra of z/OS, does this really matter? Or does it mean that, like BTAM, if something in z/OS changes in such a way as to cause BDAM to fail, then "tough buns" (as they say in the baking industry). What sort of change in z/OS could cause BDAM to fail to work? Ignoring EAV. EAV seems to be basically "VSAM only" type support. Of course, VSAM could be used to replace every other access method except for PDS. Given VSAM KSDS (keyed), ESDS (sequential), RRDS (numbered), VRRDS (variable numbered), and LINEAR (UNIX filesystems and "other"), is there something that could NOT be rearchitected to use VSAM (ignore cost)? I'll ignore some really clever BDAM code that I learned back under OS/MVT - it was really wild, using hardware keys and "polling" the existance of specific hardware keys to do "message passing" between systems. -- Trying to write with a pencil that is dull is pointless. Maranatha! John McKown -- 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
Re: BDAM vs VSAM
Rick Fochtman wrote: I don't know if BDAM was updated to use Format-1 CCWs, but IIRC, BDAM went Class-C on maintenance before the Format-1 CCW existed. In which publication/URL are these maintenance classes documented? Which publication/URL lists the various access methods and the class of maintenance assigned to them? This could be considered a definite drawback for any new application considering its use. If true. So far, I've heard absolutely NOTHING other than what I would classify as rumor. I would like to see something concrete that substantiates the original premise of this thread... -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 edja...@phoenixsoftware.com http://www.phoenixsoftware.com/ -- 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
Re: BDAM vs VSAM
Ed Jafe wrote >If true. So far, I've heard absolutely NOTHING other than what I >would >classify as rumor. I would like to see something concrete that >substantiates the original premise of this thread... I am the original poster ofthis thread. I Cannot find any URLs describeing the benefits of BDAM vs VSAM nor have I found any URLs about "classes". I posted this becaues I was looking for work and found a company that wrote there own transaction processing system. They write every their own code in Assembler Only and use BDAM. They do not use VSAM at all. thats what prompted me to originally post this question. Having stated that: I located an old OS/VS Data management macros book. That publication contains detailed documentation on BDAM and how to use it. Now forwarding to 1990, I also have a hardcopy of MVS ESA USING DATASETS. And the documentation in that documentation had the detailed BDAM examples and description removed. For the BDAM Macros the MVS/ESA USING DATASETS suggest to use VSAM, but the description and examples of using BDAM were removed. I have NOT FOUND a URL from IBM that BDAM IS NOT SUPPORTED. Also the only IBM Documentation for z/OS regarding the usage of BDAM is in the CICS Application Programmers Guide under File control. Paul D'Angelo Give back to your community. Click here to start a new career as a Police officer. http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTEe1XzDJk25bpJgPTLHPbZRfoDy0Vh971yFhPESW4AUO5CiCDw2JK/ -- 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
Re: BDAM vs VSAM
On Mon, 13 Apr 2009 18:55:20 -0500, Rick Fochtman wrote: >IIRC, CLASS-C Maintenance meant that old faults would be repaired but >that there would be no further updates to account for hardware or OS >upgrades. > >Patrick O'Keefe wrote: > >>On Mon, 13 Apr 2009 14:44:23 -0500, Rick Fochtman >> wrote: >> >> >> >>>... IIRC, BDAM went Class-C on maintenance before the Format-1 >>>CCW existed. ... IIRC, Format-1 CCW was defined with XA, circa 1982. That would mean that BDAM does not support 3380 or 3390. -- Tom Marchant -- 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
Re: BDAM vs VSAM
Tom Marchant wrote: IIRC, Format-1 CCW was defined with XA, circa 1982. That would mean that BDAM does not support 3380 or 3390. Not hardware support--software (EXCP) support for virtual CCWs. If you look in macro IEZIOB, you'll see support for Format-1 virtual CCWs for EXCP was added in 2003: */*$P1=K1J0491,HDZ11J0,031203,SJPLCC: SUPPORT FORMAT 1 CCWS @P1A*/ -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 edja...@phoenixsoftware.com http://www.phoenixsoftware.com/ -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
Re: BDAM vs VSAM
I recall, and possibly erroneously at that, that Format 1 CCWs were added into the processor architecture at the same time that MVS had support added for real storage sizes greater than 16MB, which was one of the main reasons for "expanding" with the new XA (expanded architecture) that was first made available in 1983. Bill Fairchild Software Developer Rocket Software 275 Grove Street * Newton, MA 02466-2272 * USA Tel: +1.617.614.4503 * Mobile: +1.508.341.1715 Email: bi...@mainstar.com Web: www.rocketsoftware.com -Original Message- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Edward Jaffe Sent: Tuesday, April 14, 2009 10:50 AM To: IBM-MAIN@bama.ua.edu Subject: Re: BDAM vs VSAM Tom Marchant wrote: > IIRC, Format-1 CCW was defined with XA, circa 1982. That would mean that > BDAM does not support 3380 or 3390. > Not hardware support--software (EXCP) support for virtual CCWs. If you look in macro IEZIOB, you'll see support for Format-1 virtual CCWs for EXCP was added in 2003: */*$P1=K1J0491,HDZ11J0,031203,SJPLCC: SUPPORT FORMAT 1 CCWS @P1A*/ -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 edja...@phoenixsoftware.com http://www.phoenixsoftware.com/ -- 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
Re: BDAM vs VSAM
Oh my. Haven't seen that superstition in decades. BDAM is p a i n f u l l y slow for most commercial applications. True, it still has its uses in highly specialized situations (such as a JES spool) but not for much else. BDAM performance is easy to predict/measure. Simply look that the average device response times and add a little for CPU overhead. Compare to a well tuned VSAM that approaches zero as the buffer hits and lookaside hits approach 100%. I would argue that a 'bench mark' would not be meaningful as the application context is the key factor. For example, data that is written just once and read just once may actually perform better as BDAM. Lastly, I would argue that the only meaningful metric is the total elapsed time from when the application program requests the data until it receives it measured under full load with contention. -Original Message- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of esst...@juno.com Sent: Saturday, April 11, 2009 9:35 AM To: IBM-MAIN@bama.ua.edu Subject: BDAM vs VSAM In to days Z/OS environment is BDAM faster than VSAM. I understand that IBM does not recommend the use of BDAM, however for those installations that are heavy Assembler and continue to use BDAM has there been any bench marks for the use of BDAM ? The I/OS Subsystem and Access methods have all improved since there inception. So I'm wondering why some mainframe software providers continue to choose BDAM over VSAM. Paul D'Angelo Enterprise System Software NOTICE: This electronic mail message and any files transmitted with it are intended exclusively for the individual or entity to which it is addressed. The message, together with any attachment, may contain confidential and/or privileged information. Any unauthorized review, use, printing, saving, copying, disclosure or distribution is strictly prohibited. If you have received this message in error, please immediately advise the sender by reply email and delete all copies. -- 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
Re: BDAM vs VSAM
>BDAM performance is easy to predict/measure. Simply look that the average >device response times and add a little for CPU overhead. Compare to a well >tuned VSAM that approaches zero as the buffer hits and lookaside hits >approach 100%. Apples and Turnips. You're comparing pure I/O against software logic for buffer management. Add similar logic to your BDAM program to manage it's own buffers and rerun the comparison. -- 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
Re: BDAM vs VSAM
Apple pie and turnip salad. You must also compare the development effort necessary to convert pure BDAM (without any local buffering logic added) to VSAM against the effort to develop all that local buffering logic for the pure BDAM application. Bill Fairchild Software Developer Rocket Software 275 Grove Street * Newton, MA 02466-2272 * USA Tel: +1.617.614.4503 * Mobile: +1.508.341.1715 Email: bi...@mainstar.com Web: www.rocketsoftware.com -Original Message- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Martin Kline Sent: Tuesday, April 14, 2009 11:45 AM To: IBM-MAIN@bama.ua.edu Subject: Re: BDAM vs VSAM >BDAM performance is easy to predict/measure. Simply look that the average >device response times and add a little for CPU overhead. Compare to a well >tuned VSAM that approaches zero as the buffer hits and lookaside hits >approach 100%. Apples and Turnips. You're comparing pure I/O against software logic for buffer management. Add similar logic to your BDAM program to manage it's own buffers and rerun the comparison. -- 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
Re: BDAM vs VSAM
BDAM does not buffer. You incur a synchronous wait while the bock of data is transferred from or to the device. This wait can be inferred by the average device response time. That sets a minimum time to complete the I/O request as well as an upper limit to the number of I/O's that can be performed in a given interval of time. That, in turn, sets a hard cap on the number of transactions you can process in a given interval of time. And there goes your scalability. It may be true that BDAM does an I/O a bit faster than VSAM. But VSAM aggressively tries to avoid the I/O, and, depending on the situation, does so much of the time. It may also be true that VSAM might burn more CPU if all attempts to avoid the I/O are futile. For a transaction processor, BDAM might be my choice for logging, checkpointing, etc as buffering is generally not desirable. Some modern DASD offers a 'fast write' that effectively buffers but still guarantees that the data will actually be written to non volatile storage. -Original Message- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of esst...@juno.com Sent: Tuesday, April 14, 2009 7:38 AM To: IBM-MAIN@bama.ua.edu Subject: Re: BDAM vs VSAM Ed Jafe wrote >If true. So far, I've heard absolutely NOTHING other than what I >would >classify as rumor. I would like to see something concrete that >substantiates the original premise of this thread... I am the original poster ofthis thread. I Cannot find any URLs describeing the benefits of BDAM vs VSAM nor have I found any URLs about "classes". I posted this becaues I was looking for work and found a company that wrote there own transaction processing system. They write every their own code in Assembler Only and use BDAM. They do not use VSAM at all. thats what prompted me to originally post this question. Having stated that: I located an old OS/VS Data management macros book. That publication contains detailed documentation on BDAM and how to use it. Now forwarding to 1990, I also have a hardcopy of MVS ESA USING DATASETS. And the documentation in that documentation had the detailed BDAM examples and description removed. For the BDAM Macros the MVS/ESA USING DATASETS suggest to use VSAM, but the description and examples of using BDAM were removed. I have NOT FOUND a URL from IBM that BDAM IS NOT SUPPORTED. Also the only IBM Documentation for z/OS regarding the usage of BDAM is in the CICS Application Programmers Guide under File control. Paul D'Angelo NOTICE: This electronic mail message and any files transmitted with it are intended exclusively for the individual or entity to which it is addressed. The message, together with any attachment, may contain confidential and/or privileged information. Any unauthorized review, use, printing, saving, copying, disclosure or distribution is strictly prohibited. If you have received this message in error, please immediately advise the sender by reply email and delete all copies. -- 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
Re: BDAM vs VSAM
>BDAM does not buffer. You incur a synchronous wait while the bock of data >is transferred from or to the device. This wait can be inferred by the average >device response time. It's up to the BDAM application to manage buffers itself. If it's applicable, get some storage, keep some data blocks in memory, and avoid some I/O. And, no, you do not incur a synchronous wait unless you choose to do so. That much is the same for VSAM. If the application has something else it can do after issuing the request to start the I/O, it should do so whether it is using BDAM or VSAM (or VTAM or TCPIP, or DB/2 . . .). -- 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
Re: BDAM vs VSAM
The OP asked about the difference between BDAM and VSAM. Not the difference in BDAM and VSAM application programs. Native BDAM does not buffer. Native VSAM does. -Original Message- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Martin Kline Sent: Tuesday, April 14, 2009 10:45 AM To: IBM-MAIN@bama.ua.edu Subject: Re: BDAM vs VSAM >BDAM performance is easy to predict/measure. Simply look that the average >device response times and add a little for CPU overhead. Compare to a well >tuned VSAM that approaches zero as the buffer hits and lookaside hits >approach 100%. Apples and Turnips. You're comparing pure I/O against software logic for buffer management. Add similar logic to your BDAM program to manage it's own buffers and rerun the comparison. NOTICE: This electronic mail message and any files transmitted with it are intended exclusively for the individual or entity to which it is addressed. The message, together with any attachment, may contain confidential and/or privileged information. Any unauthorized review, use, printing, saving, copying, disclosure or distribution is strictly prohibited. If you have received this message in error, please immediately advise the sender by reply email and delete all copies. -- 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
Re: BDAM vs VSAM
OP: >In to days Z/OS environment is BDAM faster than VSAM. I understand that >IBM does not recommend the use of BDAM, however for those installations >that are heavy Assembler and continue to use BDAM has there been any >bench marks for the use of BDAM ? >The I/OS Subsystem and Access methods have all improved since there >inception. So I'm wondering why some mainframe software providers continue >to choose BDAM over VSAM. Multiple questions. 1) Yes, BDAM is definitely faster than VSAM for some applications. VSAM is faster than BDAM for some other applications. 2) Most likely benchmarks have been run, however I have no evidence on hand. 3) Choosing BDAM over VSAM or visa versa can have multiple factors. For critical log files, I would definitely prefer BDAM. I want to know the data is written to disk before continuing, and not be left to wondering of VSAM got around to chaining some buffers yet. Can I force VSAM to write those buffers? Maybe, but it takes a little extra effort I wouldn't have to do with BDAM. Is it just random keyed records I want to read and write? Then VSAM might be the choice. I think the understanding that IBM does not recommend the use of BDAM may be correct - literally. Unless some document states, "IBM recommends you use BDAM for . . .," then that statement is true. They may not recommend against it either - or do they? -- 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
Re: BDAM vs VSAM
IBM Mainframe Discussion List wrote on 04/14/2009 11:08:43 AM: > I recall, and possibly erroneously at that, that Format 1 CCWs were > added into the processor architecture at the same time that MVS had > support added for real storage sizes greater than 16MB, which was > one of the main reasons for "expanding" with the new XA (expanded > architecture) that was first made available in 1983. Format 1 CCWs were added in XA (eXtended Architecture). Real storage sizes up to 64MB were implemented on 370 via IDAWs and two extra Page Table Entry bits. Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY -- 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
Re: BDAM vs VSAM
Edward Jaffe wrote: ... So far, I've heard absolutely NOTHING other than what I would classify as rumor. I would like to see something concrete that substantiates the original premise of this thread... I did find one IBM statement preferring VSAM to BDAM when using optional keys: http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d470/1.1.2.1 It says, "Optionally, BDAM uses hardware keys. Hardware keys are less efficient than the optional software keys in virtual sequential access method (VSAM)." -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 edja...@phoenixsoftware.com http://www.phoenixsoftware.com/ -- 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
Re: BDAM vs VSAM
BDAM is obsolete technology. It is still supported, but fading / moribound / whatever name you choose. It has some shortcomings and the list will grow up. From the other hand there is no planned date of BDAM end of life, and ISAM example shows that such notice period will be counted in years. So, for new project I would vote for VSAM, for existing application already using BDAM I would stay with BDAM. My $0.02 -- Radoslaw Skorupka Lodz, Poland -- BRE Bank SA ul. Senatorska 18 00-950 Warszawa www.brebank.pl Sd Rejonowy dla m. st. Warszawy XII Wydzia Gospodarczy Krajowego Rejestru Sdowego, nr rejestru przedsibiorców KRS 025237 NIP: 526-021-50-88 Wedug stanu na dzie 01.01.2009 r. kapita zakadowy BRE Banku SA (w caoci wpacony) wynosi 118.763.528 zotych. W zwizku z realizacj warunkowego podwyszenia kapitau zakadowego, na podstawie uchway XXI WZ z dnia 16 marca 2008r., oraz uchway XVI NWZ z dnia 27 padziernika 2008r., moe ulec podwyszeniu do kwoty 123.763.528 z. Akcje w podwyszonym kapitale zakadowym BRE Banku SA bd w caoci opacone. -- 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
Maintenance classes (was: BDAM vs VSAM)
On Mon, 13 Apr 2009 19:55:19 -0700, Edward Jaffe wrote: >... >In which publication/URL are these maintenance classes documented? >Which publication/URL lists the various access methods and the class >of maintenance assigned to them? >... Creation of the maintenance classes certainly preceded the web and online documentation. In fact, their obsolescence may have preceded the web. But there certainly must be some reader of IBM-Main that either remembers these or has old doc describing them. So hwere's a set of questions extending Ed's questions: What were the support classes and what did they imply? Did these morph into anything that is still relevant? What components and products fell into each class? Pat O'Keefe -- 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
