Jeremy Chadwick wrote:
On Thu, Oct 05, 2006 at 05:28:03PM +0200, Heinrich Rebehn wrote:
[EMAIL PROTECTED] [/tmp] # time dd if=/dev/zero of=/mnt/x/10MB.dat bs=1M
count=10
10485760 bytes transferred in 4.967248 secs (2110980 bytes/sec)
[EMAIL PROTECTED] [/tmp] # time dd if=/dev/zero of=/mnt/x/100MB.dat bs=1M
count=100
104857600 bytes transferred in 69.020366 secs (1519227 bytes/sec)
[EMAIL PROTECTED] [/tmp] # time dd if=/dev/zero of=/mnt/x/10MB.dat bs=1M
count=10
10485760 bytes transferred in 5.289492 secs (1982376 bytes/sec)
[EMAIL PROTECTED] [/tmp] # time dd if=/dev/zero of=/mnt/x/100MB.dat bs=1M
count=100
104857600 bytes transferred in 58.715595 secs (1785856 bytes/sec)
This isn't a valid test of performance, in my opinion. bs=1M is a
bad idea. You shouldn't be using dd for this kind-of test at all.
I should also note that bs=1M is not the same thing as obs=1M ibs=1M.
dd's weird like that (someone can explain it, I'm sure -- I've seen
it discussed in the pasT).
Ok, let's try cp:
[EMAIL PROTECTED] [~] # mount_nfs -U -L antsrv2:/export/disk2 /mnt
[EMAIL PROTECTED] [/tmp] # time cp 10MB.dat /mnt/x
real 0m6.884s
user 0m0.000s
sys 0m0.027s
[EMAIL PROTECTED] [/tmp] # time cp 100MB.dat /mnt/x
real 1m8.744s
user 0m0.000s
sys 0m0.251s
Again, this yields less than 2MB/sec :-(
scp is an ""acceptable"" real-life test (not the best, but it's
legitimate), and you only did it from antsrv1 --> antsrv2, not the
other direction. It's really too bad the OpenBSD guys refuse to
incorporate the HP (high-performance) patches into OpenSSH, and
being able to say "-c none" would *really* help when it comes to
benchmarking network I/O via scp (in our case, we do dump over ssh
across a segregated private LAN -- the encryption overhead slows
our backups down to a crawl, and is worthless in our environment
since as I said, segregated private LAN...)
So "-c none" would then have given even better performance compared to nfs.
That said:
I have seen cases where network peformance on BSD works fantastic
uni-directionally -- for example, using FTP to "get" a file from
a FreeBSD box on a 100mbit LAN results in a speed of about
300-400kbit/sec, while doing a "put" to the same box results in
90mbit/sec.
The problem in that case turned out to be duplex-related. Both
boxes were auto-negotiating with the Cisco switch correctly, and
indeed the Cisco labelled them as auto-100/full, but as anyone who
is familiar with Ciscos knows, auto-negotiation on Catalysts is
far from reliable. Both boxes reported auto-neg and being at 100/full
as well. I ended up hard-setting the boxes to use 100/full, and
set the switch ports to 100/full, then rebooted both boxes (yes,
this is sometimes required, as driver auto-neg code is a bit tweaky);
voila, problem fixed.
If you can connect these two boxes directly via a crossover cable,
and you still see the problems, then yes, there's something definitely
amiss that needs investigating. :-)
I hardcoded both machines to 1000baseTX full duplex and rebooted both:
[EMAIL PROTECTED] [/tmp] # ifconfig em0
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_MTU>
inet 134.102.176.16 netmask 0xffffff00 broadcast 134.102.176.255
ether 00:04:23:d4:94:89
media: Ethernet 1000baseTX <full-duplex>
status: active
[EMAIL PROTECTED] [/tmp] # ifconfig em0
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_MTU>
inet 134.102.176.17 netmask 0xffffff00 broadcast 134.102.176.255
ether 00:0e:0c:ba:79:a8
media: Ethernet 1000baseTX <full-duplex>
status: active
The switch is a "dumb" LinkPro GB switch with nothing to configure.
How can i connect both boxes via a crossover cable and at the same time
connect them to our lan? ANTSRV1 is our production server that i cannot
take off line!
--
Heinrich Rebehn
University of Bremen
Physics / Electrical and Electronics Engineering
- Department of Telecommunications -
Phone : +49/421/218-4664
Fax : -3341
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