VBS does NOT say all blocks are the same size. That is FBS. VBS is SPANNED, FBS is STANDARD.
As for appending to a data set (MOD) - You can always do it to a VBS, but very rarely, if ever, to a FBS. A short block in a FBS file signals EOF. Even if there is additional data after the short block, a well behaving program will not read past the short block. Chris Blaicher Principal Software Engineer, Software Development Syncsort Incorporated 50 Tice Boulevard, Woodcliff Lake, NJ 07677 P: 201-930-8260 | M: 512-627-3803 E: [email protected] -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Paul Gilmartin Sent: Monday, June 10, 2013 4:03 PM To: [email protected] Subject: Re: I/O Optimization On Mon, 10 Jun 2013 17:43:58 +0000, DASDBILL2 wrote: > >Spanned means that a single logical record might span multiple physical >blocks, but the way it is implemented results in having all block sizes be the >same, except for possibly the last one, which might be short. > Is uniform lengths a requirement? Do any applications rely on being able to calculate a cylinder and track address within a VBS data set? Is any error reported if an interior block is short? Does this mean one can't append (MOD) to a VBS data set? What happens if after writing the last segment of a logical record the block is not filled up to BLKSIZE but fewer bytes are available than the length of a SDW? I suppose using null segments might relax some of these constraints. By "the way it is implemented" are you referring to the behavior of QSAM? -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ATTENTION: ----- The information contained in this message (including any files transmitted with this message) may contain proprietary, trade secret or other confidential and/or legally privileged information. Any pricing information contained in this message or in any files transmitted with this message is always confidential and cannot be shared with any third parties without prior written approval from Syncsort. This message is intended to be read only by the individual or entity to whom it is addressed or by their designee. If the reader of this message is not the intended recipient, you are on notice that any use, disclosure, copying or distribution of this message, in any form, is strictly prohibited. If you have received this message in error, please immediately notify the sender and/or Syncsort and destroy all copies of this message in your possession, custody or control. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
