From: Jeff Mohler [mailto:speedtoys.racing@gmail.com]
Sent: Monday, October 31, 2011 9:54 AM
To: Cotton, Randall
Cc: toasters@teaparty.net
Subject: Re: Is there a graph somewhere of performance vs raid group size?

Any reason to leave performance on the table by not configuring all of what you bought in a reasonable manner?

> Simple: Committing all disks to aggregates when you don’t need to squeeze out every last bit of performance locks disks to specific nodes unnecessarily. Then, when you need more disks on a particular node, rather than just moving over disks from an underutilized node, you have to buy new disks or even a new shelf.

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> Whats a node?

The term “node” is NetApp lingo for a controller, especially in an active/active configuration. I use “node” to indicate that all my controllers are in active/active pairs.

> Whats your goal?

To configure the aggregates on my six node with something less than every last disk I have (80) so that extras are available that I can add to nodes that need it in the (somewhat unpredictable) future. This way I’m not forced to buy new disks or shelves when I have perhaps severely underutilized disks on one node that I can’t reassign because they’re locked in an aggregate. All the while, I only wish to do this to the extent that performance is not impacted too greatly – say 10 or 15%.