Re: Question about RAC

  • From: "LS Cheng" <exriscer@xxxxxxxxx>
  • To: rjamya@xxxxxxxxx
  • Date: Wed, 1 Nov 2006 12:56:04 +0100

Hi rjamya

Not RAC expert here but I wonder if you achieve good performance sharing a
couple interconnect (gigabit, infiniband?) between 55 RAC Databases? The
bottleneck I have seen in some customers most of times are due to
interconnect.

Rgds





On 10/31/06, rjamya <rjamya@xxxxxxxxx> wrote:

Okay ... some basics ... we don't partition our servers .. so no lpar etc

We run two node cluster, i.e. two physical servers in a cluster.
separate boxes. For each RAC database, we have two instances, one and
two. One instance of a RAC DB runs on one server and another on
another server.

1. SERVER A and B host two RAC databases DB_A and DB_B.
2. SERVER A runs DB_A1 and DB_B1 instances
3. SERVER B runs DB_A2 and DB_B2 instances.

Get the picture? Now step back and imagine instead of two databases
across two nodes (that is two instances per node) we run 55 instances
per node, that is 55 databases on the two node cluster.

Yes, they connect to same san, use same pair of interconnects and are
a mix of 9204, 9205, 10104 and 10202 databases.

to answer your last question, yes
xxx@yyy> ps -ef | grep pmon | wc -l gives me 50 and I know for a fact
that at-elast 4 instances are down because they are being refreshed
from production.

Hope I make it clear.
Raj

On 10/31/06, amonte <ax.mount@xxxxxxxxx> wrote:
> rjamya
>
> there wont be vpart, lpart and such, lets make a bit easier, imagine you
> have two small PCs running 2 instance each, 4 instances in total and
> supporting 2 RAC Databases, 4 instances shares Memory, CPU,
Interconnect. Is
> is logical?
>
> you said you run 55 RAC in two nodes but then you say you have a
instance
> per node....?!
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