Is Clustering the right solution for me ?

[Peter Santos]

Dear all,
I'm hoping to get some feedback about using MySQL's clustering solution. I've spent many years administering
Oracle databases, but I only have 2 weeks of experience on MySQL... so please bare with me!

Here is the problem:
- We have a web application where users browse their data. A typical session consists of 1 SELECT and/or 1
UPDATE based on a primary key. So the transactions are short and quick. We expect the read/write ratio
to be 70/30 ...since many users will SELECT their data, but never UPDATE it. This seems simple, but the problem is
that we experience very high peaks in load. We may get 1 million SELECT's per hour for 4-5 hrs straight at any time
during the day followed by 30% updates.
Currently we have Oracle handling this volume, but we are looking for another solution to handle these
short OLTP type transactions in a different system since our core business is not an OLTP environment
.... hence my inquiry into Clustering.

Since MySQL doesn't support multi-master replication, clustering seems to be the only other option. Also, the delay
between Master/Slave replication make single Master replication not an option.

I've read the documentation on Clustering and I'm just not sure it it will work. The goal here is to support my
short dml transactions in large volumes. It seems to me that clustering is more HA, and may or may not sustain
the short bursts in load that we are looking for.
The data that I would need to put in a cluster could also be anywhere between 10GB and 50GB ..so how do I
scale? ( We cannot wait for storing NDB data to disk, so MySQL 5.1 is not an option).

Also I'm still a bit confused about the architecture and how much memory would need to be on each sql node, and
data/ndb storage nodes. (I'm looked at the formula, but didn't understand it... ie NumberofReplicas? .)

TIA
--peter