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Snapshot replication capped by sshd CPU usage

Joined
Apr 13, 2017
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#1
I'm moving data from one FreeNAS to another, and I can see I'm capped by the CPU, sshd process is running at 100%.
Is there any way around that?
I'm only getting 2GBit/s with a 10Gbit NIC (that tested 9.5GBit/s to the other server with iperf3) and it annoys me :)
I also tested the storage and it's definitely capable of more.
 
Joined
Apr 13, 2017
Messages
62
Thanks
4
#2
Joined
Apr 13, 2017
Messages
62
Thanks
4
#3
So, one of the NICs crapped out on me, firmware kept crashing. I pulled it and put in an X550-T2 instead.
Since I had to restart, I decided to try the CLI way instead.
If anyone would like to know, the commands I used were these.

Sending computer: zfs send -R backup@auto-20190711.1645-2d | nc -w 20 192.168.100.8 3333
Receiving computer: nc -w 60 -l 3333 | zfs receive -F Storage

It shot the transfer speed up to 4GBit/s.
What the actual bottleneck was, I'm not sure. There appeared to be headroom on both disks and CPU.
 

jgreco

Resident Grinch
Moderator
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May 29, 2011
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#4
Since you didn't provide any information about the systems involved, it's hard to make anything more than very vague general statements.

Because replication happens over SSH, 2Gbit/s is actually fine for at least some platforms. SSH performs its encryption and any compression on a single core, so you will always be limited in that manner. iperf3 isn't doing anything computationally intensive and so the numbers you get out of that will represent the peak numbers your system can actually support, but once you start actually doing real world work, you're never going to hit that number.

Please note that you would have a better chance at getting feedback on your issue if you follow the Forum Rules, conveniently linked at the top of every page in red, which ask for a description of your hardware and general setup.
 
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