Hi Raj,
Unless your 'db_block_size' is 8192 then you should use direct I/O for all
Oracle file systems regardless of usage. Also because Oracle explicitly requests
synchronous I/O whenever it opens its datafiles, it is the convosync mount
option that counts, rather than the mincache one. Indeed, if you use
'convosync=direct, mincache=dsync' you'll get buffering for trace files or other
stuff that might also reside on your Oracle file systems, which is probably what
you want.
I can't imagine any reason why you would want buffering for rollback segment
datafiles, but assuming your block size is 8K, there is a weak argument for
buffering temporary segment datafiles. Namely that temporary segment writes are
invariably read again, and operating system buffering may save physical I/O on
the reads. Oracle does not normally buffer temporary tablespace I/O and so with
operating system buffering there is no buffering at all. However, if you machine
is dedicated to Oracle and you are willing to allow Oracle to use the memory
directly, then a better approach is to use the memory that might otherwise be
used for operating system buffering of temporary tablespace writes to increase
the 'sort_area_size' and thus avoid those writes entirely.
@ Regards,
@ Steve Adams
@ http://www.ixora.com.au/
@ http://www.christianity.net.au/
-----Original Message-----
Sent: Saturday, 28 April 2001 1:15
To: Multiple recipients of list ORACLE-L
Hi List ,
I am in the middle of Major configuration of JFS
filesystem on HP-UX 11.0 . I came across the follwing
info . Could someone validate this please ?
"The options you want are mount options available only
with Online JFS (not
a free product, unfortunately.) The options you want
are:
RBS & TEMP files : mincache=dsync, convosync=dsync
DATAFILES & REDO files : mincache=direct,
convosync=direct
"
TIA .
regards,
RS
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