Thanks I’ll look Into it > On Mar 1, 2021, at 7:16 PM, Farley, Peter x23353 > <[email protected]> wrote: > > Joseph, > > Apologies, I mis-remembered what SMB can do. SMB is available only for VSAM > files, not for concatenated QSAM files. BLSR is one of two options for > many-buffered QSAM input. > > The other option is to use the regular DD parameters NCP=nn,BUFNO=nn (max of > 99 for each one) that may or may not help with I/.O performance. I have run > some work with NCP=99,BUFNO=99 with some helpful effects, though not dramatic. > > To really take advantage of NCP/BUFNO you probably would need to code to > juggle "NCP" different READ's at a time using BSAM and your own de-blocking > subroutine. Lots of bookkeeping to keep track of them all and only CHECK in > the correct order. Robust recovery from I/O errors in such code is also a > thorny problem. Solvable, but thorny. > > Peter > > -----Original Message----- > From: IBM Mainframe Discussion List <[email protected]> On Behalf Of > Farley, Peter x23353 > Sent: Monday, March 1, 2021 1:43 PM > To: [email protected] > Subject: Re: Large block interface for VB > > EXTERNAL EMAIL > > You assume correctly, it does. In my experience both BLSR and SMB will > handle concatenations of any size without any issue. > > When using BLSR your primary DD (the one your program reads) is coded with he > BLSR parameters and nothing else, that DD then points (via a BLSR parameter) > to a second DD where you put your large concatenation. > > SMB is applied directly to your primary DD name, specify the SMB parameters > on only the first of the concatenated DD's. > > Peter > > -----Original Message----- > From: IBM Mainframe Discussion List <[email protected]> On Behalf Of > Joseph Reichman > Sent: Monday, March 1, 2021 1:36 PM > To: [email protected] > Subject: Re: Large block interface for VB > > Thank you I’m doing searches for files so I have over 100 concatenated files > does the access matters I mean I assume QSAM reads a block under the covers > > > >> On Mar 1, 2021, at 1:26 PM, Farley, Peter x23353 >> <[email protected]> wrote: >> >> Joseph, >> >> I believe that LBI is only for tape inputs and outputs. You can speed up >> your processing easier by using either the older BLSR buffering subsystem or >> better the newer SMB buffering system. See the JCL reference manual for SMB >> parameters. >> >> Allocate as much REGION as your installation will allow (some installations >> limit the maximum any job without special authorization may use, even >> sometimes production jobs). >> >> Use BLSR or SMB to allocate as many buffers as will fit in the REGION size >> you can allocate. >> >> I have seen substantial decreases in run time using these techniques with >> very large sequential files. >> >> I would also recommend using at least software compression or better >> hardware compression (if your CPU has it) for your large sequential files. >> The CPU time used for compression and decompression will sometimes be offset >> by decreases in elapsed time due to reduced I/O burdens for the compressed >> data, especially if you have hardware compression available. >> >> HTH >> >> Peter >> >> -----Original Message----- >> From: IBM Mainframe Discussion List <[email protected]> On >> Behalf Of Joseph Reichman >> Sent: Monday, March 1, 2021 1:14 PM >> To: [email protected] >> Subject: Re: Large block interface for VB >> >> Who uses tape >> >> I went to bsam trying to speed up my application wonder if going to >> bsam >> >> Does anything positive for me >> >>>>> On Mar 1, 2021, at 1:10 PM, Paul Gilmartin >>>>> <[email protected]> wrote: >>>>> >>>>> On Mon, 1 Mar 2021 11:24:57 -0500, Joseph Reichman wrote: >>>>> >>>>> It disk then documentation says the system only supports tape at this >>>>> time is That true ? >>>>> >>> Have you any reason to doubt it? >>> >>> I suspect it's a hardware limitation. >>> >>>>>> On Mar 1, 2021, at 11:22 AM, Paul Gilmartin wrote: >>>>> >>>>> On Mon, 1 Mar 2021 09:12:59 -0500, Joseph Reichman wrote: >>>>> >>>>>> I have 100 files concatenated that are normally processed by qsam >>>>>> with a lrecl 31996 and blksize 32000 >>>>>> >>>>>> Since processing takes a long time I was looking to speed things >>>>>> up by specifying a blksize of 320000 in the DCBE >>>>>> >>>>> What device type? >>>>> >>>>>> After the first read using bsam read macro I looked at the first 4 >>>>>> bytes ( Block descriptor word ) and it was x’7C4A’ which is 31,888 >>>>>> which seemed to me that it was still processing blksize of 32,000 >>> >>> -- gil >>> > -- > > This message and any attachments are intended only for the use of the > addressee and may contain information that is privileged and confidential. 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