Setfan, In OPS or RAC the locking is controlled by the
DLM which is only communicated through the
interconnect. The interconnect can be public or
private. Private interconnects are highly recommended.
Access to the data blocks by each instance is
controlled by the DLM. DLM's communicate to each other
via the interconnect. An instance cannot access a
block without obtaining a PCM lock 1st(PCM locks are
managed by the DLM). If the instance is doing a read
the PCM lock is shared and all instances doing a read
will also obtain a share lock. However if the instance
is doing a DML then that instance will get an xclusive
lock and that is the only instance that can access
that block. If another instance requires that block
then that instance has to request the holding instance
to release the lock(Global enqueue). The holding
instance writes the block back to disk the lock is
released and the requesting instance now gets the PCM
lock in a status (shared or xclusive) depending of the
whether the activity is a select or DML. Now some of
the disk I/O associated with DML changes in 9i because
of cache fusion. You will also need the Cluster
Manager that comes with your OS so Oracle can
establish the communications between the nodes. Even
if you want to install OPS an single node you still
need the CM. Without the CM and OPS you cannot have 2
instances concurrently accessing the same disks. It
doesn't matter whether the instances are on the same
machine or not.
Scott
--- Stefan Jahnke <[EMAIL PROTECTED]> wrote:
> Hi,
>
> I'm just making assumptions. According to an Oracle
> guy, with OPS on
> 8.1.7, the instances communicate via 2 different
> ways. One way is via
> network connections (process to process
> communication). The other way is
> via locking blocks and propagating it via distr.
> lock manager. So,
> according to what he said, the instance is also
> taking a look at the
> disk directly and checking the block it wants to
> read (it's a raw
> device, so there won't be a file system). What I
> don't know is, how are
> the locks propagated ? Is there a shared
> datastructure (kind of a lock
> list) that can be accessed by both instances (and
> how is it maintained
> and accessed?) or does the instance check the status
> of the block
> directly ?
>
> > Hallas John schrieb:
> >
> > That's an interesting concept. Won't there be
> problems with file
> > sharing. Once the first instance has started will
> the 2nd one be
> > allowed access to the datafiles?. I don't know
> much about raw files
> > but I suspect that would be the problem area.
> >
> > -----Original Message-----
> > From: Stefan Jahnke
> [mailto:[EMAIL PROTECTED]]
> > Sent: 04 September 01 08:40
> > To: Multiple recipients of list ORACLE-L
> > Subject: OPS on a single machine ?
> >
> > Hi,
> >
> > I was wondering if it is possible to set up OPS on
> a single machine.
> > Maybe like this:
> > 1 disk as a raw device, then set up an instance to
> use the raw device
> > and set up parallel server's second instance to
> use the raw device,
> > too.
> > Before I go through the hassle just to find out
> that it doesn't work,
> > did anybody try this before ?
> >
> > (I'm on SuSE 7.2, Oracle 8.1.7 with OPS option)
> >
> > --
> > ----------------------------
> > | Regards, |
> > | Stefan Jahnke |
> > | BOV AG |
> > | @:D2 Vodafone, Abt.: FBOM |
> > | Tel.: 0211/533-4893 |
> > ----------------------------
> > --
> > Please see the official ORACLE-L FAQ:
> http://www.orafaq.com
> > --
> > Author: Stefan Jahnke
> > INET: [EMAIL PROTECTED]
> >
> > Fat City Network Services -- (858) 538-5051
> FAX: (858) 538-5051
> > San Diego, California -- Public Internet
> access / Mailing Lists
> >
> >
>
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> --
> ----------------------------
> | Regards, |
> | Stefan Jahnke |
> | BOV AG |
> | @:D2 Vodafone, Abt.: FBOM |
> | Tel.: 0211/533-4893 |
> ----------------------------
> --
> Please see the official ORACLE-L FAQ:
> http://www.orafaq.com
> --
> Author: Stefan Jahnke
> INET: [EMAIL PROTECTED]
>
> Fat City Network Services -- (858) 538-5051 FAX:
> (858) 538-5051
> San Diego, California -- Public Internet
> access / Mailing Lists
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Author: Scott
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