I would have thought my netcat test would only be limited by the GigE card and PCI-X bus (which should have enough bandwidth to saturate GigE).
Using ncat, instead of ncat, I get 118 MB/s dumping from /dev/zero and 95 MB/s from my array. I never would have guesses that nc had so much overhead! Perhaps I was mistaken and I really don't have the problem I think I have with network performance. It's Samba... 12:40:24-root@screamer:/mnt/tmp/ISOs $ dd if=linuxmint-12-gnome-dvd-64bit.iso bs=8k of=/dev/null 130190+1 records in 130190+1 records out 1066518528 bytes (1.1 GB) copied, 29.3757 s, 36.3 MB/s Thanks for all the help. Now I have some direction as to what I need to be looking at more. Jeff * Gustin Johnson <gus...@meganerd.ca> [2012-03-29 11:18:14 -0600]:
netcat (or ncat) would still be subjected to PCI/PCI-X bus limitations. So basically when troubleshooting I would change the cables, then the switch, then the NICs. The regular PCI bus tops out at a gigabit, so you should still be able to test with a standard PCI (though PCI-E would be better) NIC. Intels are pretty nice but pricey for PCI (~$50). I have used SMC2-1211TX which are cheap and pretty good Gig-E NICs. Install atop to help figure out why a CPU/core gets pinned. Use ncat (part of nmap) as it is a cleaner more modern implementation. I would build it from source. If you have the memory, try creating a RAM disk and put a real 1 or 2 GiB file in it. Use that to transfer as /dev/zero can give weird results sometimes and /dev/urandom puts load on the CPU and bus. Hth, On Thu, Mar 29, 2012 at 9:12 AM, Stolen <sto...@thecave.net> wrote:Try using iperf to test *just* the network. http://sourceforge.net/projects/iperf/?_test=b On 12-03-29 08:50 AM, Jeff Clement wrote: I don't think that's the problem though. I can get > GigE read speeds from my array. 08:46:27-root@goliath:/etc/service/dropbox-jsc $ hdparm -t /dev/lvm-raid1/photos /dev/lvm-raid1/photos: Timing buffered disk reads: 512 MB in 3.00 seconds = 170.49 MB/sec Write speeds are obviously slower but decent. 08:47:48-root@goliath:/mnt/photos $ dd if=/dev/zero of=test bs=8k count=100000 100000+0 records in 100000+0 records out 819200000 bytes (819 MB) copied, 10.3039 s, 79.5 MB/s So I would expect that I should be able to saturate GigE on the reads and do ~80 MB/s on the writes. However what I'm seeing whether I'm doing IO to disk or just piping from /dev/zero to /dev/null is around 40MB/s. It looks like my bottleneck is actually the network. The netcat test should eliminate disk IO and also eliminate the PCI-X bus as the bottle neck. I think... Jeff * Andrew J. Kopciuch <akopci...@bddf.ca> <akopci...@bddf.ca> [2012-03-29 08:18:14 -0600]: Anyone have any ideas what I should be looking at in more detail. Thanks, Jeff You are probably limited by the i/o speeds of the hard drives. Your LAN can sustain around 125MB/s, but your hard drives will not be able to read / write that fast, you will be bound to their maximums. HTH Andy _______________________________________________ clug-talk mailing list clug-talk@clug.ca http://clug.ca/mailman/listinfo/clug-talk_clug.ca Mailing List Guidelines (http://clug.ca/ml_guidelines.php) **Please remove these lines when replying _______________________________________________ clug-talk mailing listclug-talk@clug.cahttp://clug.ca/mailman/listinfo/clug-talk_clug.ca Mailing List Guidelines (http://clug.ca/ml_guidelines.php) **Please remove these lines when replying _______________________________________________ clug-talk mailing list clug-talk@clug.ca http://clug.ca/mailman/listinfo/clug-talk_clug.ca Mailing List Guidelines (http://clug.ca/ml_guidelines.php) **Please remove these lines when replying
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