Multiple virtual SCSI Controller Benefits?

[bsohn]

Is there any benefit to using multiple SCSI controllers on a guest?  Thanks.  

[BilBens · Accepted solution]

VMware highly recommends using multiple virtual SCSI controllers for the database virtual machines or
virtual machines with high I/O load. The use of multiple virtual SCSI controllers allows the execution of
several parallel I/O operations inside the guest operating system.

For more info (Page 18)

http://www.vmware.com/files/pdf/partners/oracle/Oracle_Databases_on_VMware_-_Best_Practices_Guide.pd...

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Bil Bens

[bsohn]

Great, thanks!

[jrmunday]

You are limited to 4, and I would certainly make use of multiple controllers - MS-SQL is a great case for this. Depending on guest OS, use the PV SCSI controller for performance if you can.

I have actually spent the last couple of weeks benchmarking different tiers of storage, and in most cases I saw the best performance when using multiple LUN's (especially as you scale the load out). So this, in combination with additional controllers will give you a good start to setup your own iometer access specifications for testing - just make sure your disks are aligned as this makes a huge difference to performance.

Cheers,

Jon