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AIX j2_maxPageReadAhead vs maxpgahead

In AIX

# ioo -a|grep head
j2_maxPageReadAhead = 128
j2_minPageReadAhead = 2
maxpgahead = 8

what is the difference between
j2_maxPageReadAhead vs maxpgahead ?
and why minpgahead is not showing?

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woolmilkporc

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it-rex

ASKER

How can I tell which file system I have?

woolmilkporc

Issue

lsfs

You will see the respective filesystem type in column 4 ("VFS").

it-rex

ASKER

lsfs
Name Nodename Mount Pt VFS Size Options Auto Accounting

/dev/oraclelv08 -- /ora08 jfs2 -- rw yes no

this is the one used by ASM right?

woolmilkporc

OK, it looks like being used by Oracle.

But doesn't ASM use its own filesystem implementation, acfs?

it-rex

ASKER

Do you mean OCFS?
that if you are using RAC but we are not it is just a stand alone server using ASM.

woolmilkporc

Anyway, ASM works on raw volumes, the I/O subsystem is directly handled by the Oracle kernel.

So standard AIX tuning will have no effect.

The filesystem whose characteristics you posted is a regular AIX jfs2 filesystem, so the "j2_..." tuning paraneters apply.

Seems we have disparate notions of ASM here ...

Try in SQL*Plus

SET PAGESIZE 100
SELECT VOLUME_NAME, VOLUME_DEVICE FROM V$ASM_VOLUME;

(in a non-ASM instance you won't get any output)

and

SET PAGESIZE 100
SELECT NAME FROM V$DATAFILE;

it-rex

ASKER

thanks