Choosing CPU

Elliott

Dabbler
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Sep 13, 2019
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40
How important is CPU speed and cores for a FreeNAS? I think the total amount of storage doesn't matter much, but increased total throughput to clients does. Is there some guideline formula for estimating CPU usage? I'm guessing 1 core per client would be the bare minimum.
I'm thinking of doing 11 raidz2 vdevs, each with 9x 14TB disks for 1PB usable capscity. I will be storing large files, so sequential bandwidth is more important than IOPS. With this configuration, I expect to get around 12GBps total throughput, assuming each disk is 170MBps. I may have 10 clients each on 10GbE with a mix of SMB and NFS.

Also, does ZFS / FreeNAS have any Intel specific optimizations or should it perform well on AMD Epyc too?
 

Jessep

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Aug 19, 2018
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SMB is mostly single threaded so you want higher speed cores rather than more cores for performance. I would expect 8-10 core with as high of speed as you can afford.

Something like Xeon Gold 6244 8 core 3.6GHz base 4.4GHz turbo
https://ark.intel.com/content/www/us/en/ark/products/192442/intel-xeon-gold-6244-processor-24-75m-cache-3-60-ghz.html

Should only require single CPU unless you want a LOT of RAM.

Performance will also depend on RAM amount for ARC. 192GB (32GB DIMMs) or 384GB (64GB DIMMs) would be a good starting place, more if your ARC hit rate isn't high enough. Might be best to start with 64GB DIMMs to allow for upgrades if staying with single CPU.
 

Elliott

Dabbler
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Sep 13, 2019
Messages
40
Thanks Jesse. With samba being single threaded, I think that means one thread per client, not one thread total, right? So then 0.5 core per client (hyperthreading) plus a few extra, and that's about what you have said.

AMD Threadripper 2950X looks perfect, it's 16 cores at 3.5GHz, with 4.4GHz turbo. Supports ECC and only costs $650. Unfortunately I can't find any server chassis and motherboard designed around this platform. Most machines in this class use dual Xeon and populating only one socket means you lose important PCIe slots. Two Xeon 6144's would cost nearly 6 grand. Xeon Gold 5222 is cheaper and 3.8GHz, but 4 cores is not enough.
AMD Epyc clock speeds are probably too low.
 
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