Florian Philipp wrote:
> Hi!
> 
> I've got two questions concerning LVM2.
> 
> Number one: What stripesize parameter would you use? The manual of my 
> mainboard advises to use 64k for a RAID-0. Would that be useful for my 
> portage tree or a more conventional partition like /usr and /var?
> 
> Number two is not really a performance issue but it's LVM2-related: 
> LVM2-mirrors need an extra log device but the man pages don't tell anything 
> about how large it has to be or if it can be a partition or loop device on 
> the same hdd as one of the mirrors.
> 
> Thanks in advance!
> 
> Florian Philipp

Sizing I/O subsystems is highly workload and filesystem dependent, and
there's really no such thing as a one-size-fits-all quick answer. There
are models and there are some really good I/O subsystem benchmarks you
can use once you know what your workload characteristics are.

I highly recommend the book "Storage Network Performance Analysis"
http://www.amazon.com/Storage-Network-Performance-Analysis-Huseyin/dp/076451685X/
for the tools to do this. But one thing you can do first is to run your
workload on a system and capture data with "iostat". If you don't have
"iostat", you'll need to emerge "sysstat". The "iozone" benchmark is in
Portage, as is bonnie++. The I/O benchmark I like most is IOMeter, but
that requires a Windows system to run the control console and
downloading a Linux agent from their web site.
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