Hi, On 04/29/2015 04:06 PM, Garrett Wollman wrote:
If you're using one of the drivers that has this problem, then yes, keeping your layer-2 MTU/MRU below 4096 will probably cause it to use 4k (page-sized) clusters instead, which are perfectly safe. As a side note, at least on the hardware I have to support, Infiniband is limited to 4k MTU -- so I have one "jumbo" network with 4k frames (that's bridged to IB) and one with 9k frames (that everything else uses).
So I was thinking, a customer of mine runs mostly the same setup, and has no issues at all. The only difference, MTU of 1500 vs MTU of 9000. I also created a graph in munin, graphing the number of mbuf_jumbo requests and failures. I find that when lots of writes occur to the iscsi-layer, the number of failed requests grow, and so so the number of errors on the ethernet interface. See attached images. My customer is also not suffering from crashing ctld-daemons, which crashes every other minute in my setup. So tonight I'm going to switch to an MTU of 1500, I'll let you know if that helped. Regards, Mark Schouten _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
