Thanks, Steve. I was under the impression that in the scenario you described, that adding records to the end of the dataset and filling up the last CI in the CA would trigger a CI split which would in turn trigger the CA split.
Rex -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Steve Thompson Sent: Thursday, March 14, 2024 7:55 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: [EXTERNAL] Re: VSAM split activity and statistic questions Yes, you can have a CA split without a CI split. You add a record that needs to go into a new cylinder because there is no room in the current one. Take, for instance, a file that has records added to it using the date and time for the key. Now you add 20 records, so we will say that 5 records will fill a cylinder for our argument. Assuming it hasn't changed, each cylinder is a CA. So you fill up a CA and then have to go to a new one. There are no CI splits in doing this with the proviso that the records are added in sequentially increasing order. CI splits happen when you need to insert in the "middle" of a CA and it causes the split and this requires there to be free space when that happens (if free space is specified which can be "ALTERed" in after initially loaded). HTHs Steve Thompson On 3/14/2024 5:49 PM, Pommier, Rex wrote: > Hello list, > > I have a couple questions about VSAM KSDS and splits. For example, if I > create a KSDS with FSPC(0 0) and load it, there is no free space in it. I > then come along and try to insert a record somewhere in the middle of a CI. > This will result in a CI split which will then result in a CA split. Does > this sequence result in both a CI and CA split in the VSAM statistics? > Assuming that this scenario results in an increment in both the CI and CA > split counts, is there any way a VSAM dataset can incur a CA split without a > corresponding CI split? I am looking at a test VSAM that was built with > minimal free space (3 0) and then it had a batch job run against it, doing > inserts, deletes and a minor amount of updates. Once the job ended I looked > at the statistics and found this: > > SPLITS-CI----------50319 > SPLITS-CA----------50555 > > Variable length records, average length 380, max length 4500. CISZ 18432. > Non spanned records. > > How can I have 200 more CA splits than CI splits? > > Thanks, > > Rex > > ---------------------------------------------------------------------- > The information contained in this message is confidential, protected from > disclosure and may be legally privileged. If the reader of this message is > not the intended recipient or an employee or agent responsible for delivering > this message to the intended recipient, you are hereby notified that any > disclosure, distribution, copying, or any action taken or action omitted in > reliance on it, is strictly prohibited and may be unlawful. If you have > received this communication in error, please notify us immediately by > replying to this message and destroy the material in its entirety, whether in > electronic or hard copy format. Thank you. > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- The information contained in this message is confidential, protected from disclosure and may be legally privileged. If the reader of this message is not the intended recipient or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any disclosure, distribution, copying, or any action taken or action omitted in reliance on it, is strictly prohibited and may be unlawful. If you have received this communication in error, please notify us immediately by replying to this message and destroy the material in its entirety, whether in electronic or hard copy format. Thank you. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
