Re: Inconsistent multi-block io

On Jul 7, 4:19 pm, mak...@xxxxxxxxx wrote:
I'm on 10gR2 on AIX with ASM. have DB_FILE_MULTIBLOCK_READ_COUNT=16 in
spfile. but still see different block size for "db file scattered
read" ranging from 2 to 16. Can someone explain why its ranging from
2-16? Shouldn't DBRC always be followed if it's set in SPFILE?

see below excerpts from 10046 trace file.

WAIT #3: nam='db file scattered read' ela= 48396 file#=61 block#=416
blocks=5 obj#=80135 tim=1526895870393
WAIT #3: nam='db file scattered read' ela= 8210 file#=61 block#=33717
blocks=4 obj#=80135 tim=1526895880210
WAIT #3: nam='db file scattered read' ela= 7306 file#=61 block#=52614
blocks=3 obj#=80135 tim=1526895897691
WAIT #3: nam='db file scattered read' ela= 8508 file#=61 block#=53030
blocks=16 obj#=80135 tim=1526896239141
WAIT #3: nam='db file scattered read' ela= 15903 file#=61 block#=53046
blocks=15 obj#=80135 tim=1526896258427
WAIT #3: nam='db file scattered read' ela= 921 file#=61 block#=53379
blocks=2 obj#=80135 tim=1526896507844

Thanks

And it is being followed, as it's the MAXIMUM number of blocks to be
read in one I/O operation. None of your read operations exceed 16
blocks, so there is no problem.


David Fitzjarrell
.

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