Re: 100Mbps Ethernet Speed/Efficiency
From: Joel Jaeggli (joelja_at_darkwing.uoregon.edu)
Date: 04/07/04
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Date: Tue, 6 Apr 2004 15:38:40 -0700 (PDT) To: Neall <neall@haughtmail.com>, For users of Fedora Core releases <fedora-list@redhat.com>
On Tue, 6 Apr 2004, Neall wrote:
>
> >> I'm wondering what's the maximum sustained transfer rate
> >> that one can experience when using a 100Mbps link?
>
> I took the hard drives out of the picture. I set up RAM disks on two
> different systems, and connected them via ethernet using NFS to cross
> mount them. Then, I copied from the first system's RAM disk over
> ethernet, to the second system's RAM disk. Granted, NFS is in the
> picture, but it would be using hard drives, too.
>
> These numbers include NFS overhead (obviously):
>
> 100 Mb file:
> 100/T: 11.335 MByte/Sec (averaged over many tests).
> 1000/T: 69.9 MByte/Sec.
>
> Obviously, the 1000/T (gigabit) test would have immediately been
> bottlenecked by the drive transfer rates.
You can build a pretty wicked disk subsystem these days. single 15k rpm
disk-drives can read a rate of around 86-78MB/s depending on what part of
the disk you're hitting. even 7200rpm ide disks (80GB per platter models)
can sustain in the mid 60's. having the disk controllers sit on the same
pci bus with the ethernets can be a bottleneck as well.
> The 100/T rates are near
> theoretical. Not sure where the 1000/T bottle neck is, but I used stock
> NFS parameters.
Do the machines in question have the ethernet in 64 bit pci slots?
block reads on 4GB files from a netap-940 we were testing were order of
83MB/s using jumbo 9k ethernet frames... dropping that to 1500mtu made it
fall back to 62MB/s. ethernets in this case were broadcom BCM5702X (64 bit
66mhz)on the rioworks hdama opteron mainboard with a dell 5212 copper gig
switch for the interconnect.
> I may try to transfer via socket or rpc, but just haven't
> gotten there yet. I figured most people transfer via NFS (or SAMBA)
> mounted drives, so wanted to start there.
You can pretty much fill up 100baset in a switched lan enviroment. and you
applications will get pretty darn close even without any tunning. ftp
transfer of the fc2 test2 isos to my desktop this morning averaged around
9.5MB/s (the ftp server is gig connected but on a different subnet than my
desktop which just has 100baset. For small switched environments where
performance is important unmanged gig copper switches now cost order of
$20 a port or less, so if you need the speed it may be cheap.
> Still, ~70 MByte/sec isn't shabby over gigabit ethenet via NFS. Neall
>
>
>
>
-- -------------------------------------------------------------------------- Joel Jaeggli Unix Consulting joelja@darkwing.uoregon.edu GPG Key Fingerprint: 5C6E 0104 BAF0 40B0 5BD3 C38B F000 35AB B67F 56B2 -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: http://www.redhat.com/mailman/listinfo/fedora-list
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