DL360, discs SAS or SAS-2, controllers and performance questions

[Anton2010]

Maybe not the best headline, but bottom line: Please give me some feedback here:

If I buy a DL360 G6 with controller: Array P410i med 512MB BBWC (the standard controller in DL360 adn DL380) and I need 4 big discs.

Then I would like to buy:
4 x Dual Port Enterprise - harddisk - 300 GB - SAS-2 - 15000 rpm

But I wounder why SAS-2 is cheaper than SAS when performance is better with SAS-2 or am I wrong ? If I want the best possible access to the data on the disc, is a ´72 GB SAS or SAS2 better than a 300GB

Also I believe Raid 1+0 is the best option.

I will need to run VMWARE with MS SQL2008 inside, so I will prefer to have the best possible setup and the DL360 with 64 GB ram fits to my budget.

Antother question: If i buy a DL380 and 8 discs, what about controller limit, do I need an extra due to to much i/o traffic and how can it be calculated ?

Hope to receive a good advice

Claus

[Mark Woodruff]

Current disks can be cheaper than older ones because the recording density is higher (fewer platters/parts for the same capacity disk) and because of other manufacturing improvements. Even so, more actuators CAN always be faster than fewer; there are so many variables that it's hard to say anything definitive.

You might google "vmware disk performance" and take a look at some of the pages and white papers out there. In general, it takes a lot of work to tune a system. Starting off with a 1+0 system is a pretty safe bet. On an array, you can also configure different volumes with different RAID types (1, 0, etc) so you can try things out. It's always easier to create smaller volumes and expand them later than to create one giant one.

If you can't afford any downtime, don't forget to budget for some spare drives too.