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DB2 manages the data on the DB2 Log datasets and therefor some of what you see in the LISTCAT may be imprecise. I think until the VSAM file is closed, some of this information is not current. Next, the HI-A-RBA (High available space for the RBA) and HI-U-RBA (Hi USED RBA), as others have pointed out, shows what VSAM thinks is allocated and used within the LDS. Since this file is open, it may or may not be accurate. What problem are you trying to solve? What issues are you seeing? Are you the DB2 DBA or DB2 Sysprog? Are you having your log files switch to often or not often enough? Lizette > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of John Eells > Sent: Tuesday, April 26, 2016 7:03 AM > To: [email protected] > Subject: Re: Question about space allocation from Listcat display > > (Please consider posting via the list server, where more people will see your > posts.} > > Welcome to disk allocation! > > Assuming 4096-bytes per for unkeyed records you get about 86.7% of the track > length for actual data. You can see that record size gives you 12 records per > track below in the LISTCAT output. 4096 * 12 = 49,152 bytes per track, not > 56,664. In other words you will use a bit more than 15% more space than you > seem to have expected. > > The High RBA (minus the zero Low RBA) divided by 4096 yields 1,024,128 > records. Dividing by 12 yields 85,344 tracks. Subtracting the low CCHH from > the high and muliplying it out gives me 85,340 tracks. The "extra" four > tracks are, I'd expect, from the allocation increment of > 21,336 per extent, though you did not show the extent sizes on volumes 2-4. > > That is simply how it works. If we had warning messages for such "wasted > space," we would have them for virtually every data set. > > [email protected] wrote: > > Dear all, > > > > I have this dataset (which is a DB2 active log, a VSAM LDS) > > > > Command - Enter "/" to select action Tracks %Used > XT > > ---------------------------------------------------------------------------- > -- > > DSNDBP0.DBP1.LOGCOPY1.DS09 > > DSNDBP0.DBP1.LOGCOPY1.DS09.DATA 85344 ? > 4 > > > > > > When i do LISTCAT on it, i get : > > > > DATA ------- DSNDBP0.DBP1.LOGCOPY1.DS09.DATA > > IN-CAT --- CATALOG.X.DB201 > > HISTORY > > DATASET-OWNER-----(NULL) CREATION--------2016.004 > > RELEASE----------------2 EXPIRATION------0000.000 > > ACCOUNT-INFO-----------------------------------(NULL) > > ALLOCATION > > SPACE-TYPE---------TRACK HI-A-RBA------4194828288 > > SPACE-PRI----------21336 HI-U-RBA------4194828288 > > SPACE-SEC--------------0 > > VOLUME > > VOLSER------------DB2Y87 PHYREC-SIZE---------4096 > > DEVTYPE------X'3010200F' PHYRECS/TRK-----------12 > > VOLFLAG------------PRIME TRACKS/CA--------------3 > > STRIPE-NUMBER----------1 > > EXTENTS: > > LOW-CCHH-----X'00020000' LOW-RBA----------------0 > > HIGH-CCHH----X'05900005' HIGH-RBA------4194828287 > > > > (...) > > VOLUME > > VOLSER------------DB2Y90 PHYREC-SIZE---------4096 > > DEVTYPE------X'3010200F' PHYRECS/TRK-----------12 > > VOLFLAG------------PRIME TRACKS/CA--------------3 > > STRIPE-NUMBER----------4 > > EXTENTS: > > LOW-CCHH-----X'00020000' LOW-RBA----------------0 > > HIGH-CCHH----X'05900005' HIGH-RBA------4194828287 > > > > ==> The data set is on 4 volumes, with 21336 trks on each = 85344 tracks, as > read with 3.4. > > > > What i don't understand is that HI-A-RBA and HI-U-RBA is 4194828288, which > corresponds to phyrec-size*phyrecks/trk * 85344. > > > > I would expect that at least the HI-A-RBA should be 85344 * 56K = > > 4893966336 ??? => there is about 0.8 GB wasted in this allocation In the > listcat data displayed, there is nothing saying that there is a waste ? > > > > Can you comment about this ? > <snip> > > -- > John Eells > IBM Poughkeepsie > [email protected] > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
