[Beowulf] OT: effective amount of data through gigabit ether?

Sean Dilda agrajag at dragaera.net
Mon Oct 4 14:23:05 PDT 2004

On Mon, 2004-10-04 at 16:40, Mike wrote:
> I know this is off topic, but I've not found an answer anywhere.
> On one IBM doc it says the effective throughput for 10Mb/s is
> 5.7GB/hour, 100Mb/s is 17.6GB/hour, but only lists TBD for 1000MB/s.
> Does anyone know what this effective number is? This is for
> calculating how long backups should take through my backup network.

Those are interesting numbers.  I calculate the peak numbers to be:
10MB/s - 4.19GB/hour (less than your IBM number)
100MB/s - 41.9GB/hour (way more than your IBM number)
1000MB/s - 419GB/hour

In reality, the answer depends on your hardware.  With my setup I've
pushed 114MB/s over gigabit for an excess of ten minutes, which tends to
average out all the bursts.  If I took that out, it'd come to about

> (I'm not interested in how long it takes to read/write the disk,
> just the network throughput.)

See now, that's the trick.  Gigabit maxes out around 119MB/s.  I've not
tended to see disks that can actually preform that well (maybe with
sequential data, but not with random data).

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