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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]
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