Re: 10g RAC: max performance & min cost with miSCSI?

About the application: we are running a multi-purpose consolidated database that has almost everything you can imagine of: access from web applications, queries issued from SQL*Plus and Discoverer, some large batch inserts/updates. The database size is currently about 300 GB and is excpected to be remain under 600 GB. The database is read intensive so over 90% of operations are reads. But we can't ignore the write performance since there are a couple of large long-running batch updates. I can't give you exact numbers what is the requirement for IO peformance since there are no exact numbers. Currenlty the users are quite happy. What I want now is to put the new system up so that the performance will be blistering at the beginning and remain tolerable for four years without hardware change.

I am planning to put 8 GB RAM to both RAC nodes, or maybe 12 GB to be safe. The processors on the nodes will be the fastest available single core Xeons or AMDs. Multi core seems to be out of the question since Oracle has this stupid licensing model.

I have now come up with another storage system proposal. We could use HP MSA500 G2 units. We need two of them and both with High Availability Kit. MSA500 list price is about 4500 euros and HA kit is 4000 euros, so we need to pay 17000 euros for the disk arrays compared to 8000 euros when using MSA30 MI. MSA500 & HA kit includes all needed HBA PCI-X cards and offers possiblity for "hardware raid". And now we can use Xeon/AMD servers instead of going up to Itanium.

We could also use two MSA500 G2 units without HA kit. Both MSA500s could be connected to both nodes and ASM could be configured to treat the disks so that the first MSA500 is failure group 1 and the second is failure group 2. With this configuration HA kits wouldn't be needed and the disk system would still tolerate a single point of failure. Price of the disk arrays drops from 17000 euros to 9000 euros. What we want in this configuration is to configure MSA500 to present each disk as a plain no-raid disk to the nodes. Wondering if MSA500 can do that or does it enforce using some RAID level. Couldn't find the answer from the User's Guide.

Assumably two MSA500 units can give similar IO speed than two MSA30 MI units since the internal structures are similar (two U320 SCSI busses, 7 disk slots each). What I don't know is how will the storage processor of MSA500 perform. It could be the bottleneck here. I have been warned that the storage processors of these cheap disk systems might be quite slow. According to MSA500 User's Guide MSA500 with two SPs (HA kit) runs the SPs active-passive, so only one SP is active. So what we have is two MSA500 both having one SP active despite of having HA kit installed or not. Still wondering if a MSA500 storage processor can deliver the required 250 MB/s to get total 500 MB/s of IO out of two MSA500 G2 arrays.

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Heikki