In asking about ZFS performance in streaming IO situations, discussion
quite quickly turned to potential bottlenecks. By coincidence, I was
wondering about the same thing.
Richard Elling said:
We know that channels, controllers, memory, network, and CPU bottlenecks
can and will impact actual performance, at least for large configs.
Modeling these bottlenecks is possible, but will require more work in
the tool. If you know the hardware topology, you can do a back-of-the-napkin
analysis, too.
Well, I'm normally a Mac guy, so speccing server hardware is a bit of a
revelation for me. I'm trying to come up with a ZFS storage server for a
networked multimedia research project which hopefully has enough oomph
to be a nice resource that outlasts the (2-year) project, but without
breaking the bank.
Does anyone have a clue as to where the bottlenecks are going to be with
this:
16x hot swap SATAII hard drives (plus an internal boot drive)
Tyan S2895 (K8WE) motherboard
Dual GigE (integral nVidia ports)
2x Areca 8-port PCIe (8-lane) RAID drivers
2x AMD Opteron 275 CPUs (2.2GHz, dual core)
8 GiB RAM
The supplier is used to shipping Linux servers in this 3U chassis, but
hasn't dealt with Solaris. He originally suggested 2GiB RAM, but I hear
things about ZFS getting RAM hungry after a while. I dug up the RAID
controllers after a quick look on Sun's HCL, but they're pricy for
something that's just going to give JBOD access (but the bus
interconnect looks to be quick, on the other hand).
I guess my questions are:
- Does anyone out there have a clue where the potential bottlenecks
might be?
- Is there anywhere where I can save a bit of money? (For example,
might the SuperMicro AOC-SAT2-MV8 hanging off the PCI-X slots
provide enough bandwidth to the disks?)
- If I focused on simple streaming IO, would giving the server less RAM
have an impact on performance?
- I had assumed four cores would be better than the two faster (3.0GHz)
single-core processors the vendor originally suggested. Agree?
Many thanks for any thoughts,
adam
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