RE: RAC
- From: "Paul Harrison" <cure@xxxxxxxxxxxxx>
- To: <martin.a.berger@xxxxxxxxx>
- Date: Thu, 15 Mar 2012 15:27:23 -0500
Does the RDBMS instance request the extents per query or does it store then
for later use(other queries) ?
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Martin Berger
Sent: Thursday, March 15, 2012 3:18 PM
To: cure@xxxxxxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: RAC
the best source I have found:
Oracle Automatic Storage Management: Under-the-Hood & Practical Deployment
Guide
p246:
File Open
When an RDBMS instance needs to open an ASM file, it sends to the ASM
instance a file-open request, with the filename, via one of the o0nn
processes. ASM consults the File Directory to get the extent map for the
file. ASM sends the extent map to the RDBMS instance. In Oracle Database
10g, for datafiles, ASM sends the entire extent map to the RDBMS instance at
file-open time. In Oracle Database 11g, for datafiles, ASM initially sends
the 60 direct extents to the RDBMS instance. For the remaining extents,
which are located in indirect extents, the RDBMS requests subsequent extent
map sections on demand.
ASM delivers all the extent map pointers in the same indirect extent as the
requested file extent.
does this answer your question?
On Thu, Mar 15, 2012 at 19:03, Paul Harrison <cure@xxxxxxxxxxxxx> wrote:
> Hi All,
>
> RAC.. In database instance... I query for some data and the database
> instance has to communicate with the asm instance in order to get the
> path to the block within the asm disk group. Does the asm instance
> return all the pointers to the blocks one time(one round trip) or round
trip per block?
>
> Thanks,
> Paul
>
>
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