I think it’s quite reasonable to only allocate resources when needed. IT shops don’t always have perfect control over their purchasing budget’s granularity, most of us are asked to forecast at least a year in advance what our requirements will be.
That being said it’s a good idea to set up your RG’s and aggrs in a way that makes it easy to cleanly adding capacity. Having one 4 disk RG and two others with 16 spindles is probably not a good idea.
From: toasters-bounces@teaparty.net [mailto:toasters-bounces@teaparty.net] On Behalf Of Cotton, Randall
Sent: Monday, October 31, 2011 10:23 AM
To: toasters@teaparty.net
Subject: RE: Is there a graph somewhere of performance vs raid group size?
From: Jeff Mohler [mailto:speedtoys.racing@gmail.com]
Sent: Monday, October 31, 2011 12:42 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.
R