I know I am slightly late but I have been losing some
sleep and lot of
patience with my project(s) so bear with me : ).
The question was
" The ideal mounting option for ORACLE on JFS ?
suggested is
RBS & TEMP files : mincache=dsync, convosync=dsync
DATAFILES & REDO files :
mincache=direct,convosync=direct "
Before jumping to answers definition of some terms
used .
CONVOSYNC : This option determines how synchronous
writes are treated
direct : Bypassing system buffer
dsync : A write operation returns to the
caller after the data has been
transferred to external media, but the
inode is not updated
synchronously if only the times in the
inode need to be updated
MINCACHE : The mincache mount option determines how
ordinary writes are treated.
Can have the same values .
I did some digging around and found some details
First :
The answer by Steve ,
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.
Christian Bilien :
The advice given looks good to me. Online JFS must
indeed be
separately purchased.
In light of the above and my research ,
DATAFILES , RBS , TEMP :
mincache=direct,convosync=direct,nodetainlog
REDOLOG , ARCHIVE :
mincache=dsync,convosync=dsync
Any comments welcome .
regards ,
RS
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