Questions on network transfer rates

[Stefan Esser]

1) You can get 1MByte/s ethernet transfer rate between two 5000/200s. 
   Precondition is:
    - the file to transfer fits into the buffer cache of the sending machine.
    - the destination is '/dev/null'.
   What you tested was the write speed of you SCSI hard disk. 
   Because of SCSI overhead and lack of a write cache on the drive 
   you get at most 1 transfer of 8 KByte per revolution.
   Actually its more like: 

	8KByte * BytesPerTrack / (BytesPerTrack + 8KByte) * RevPerSecond

   because the next write starts, where the previous ended.
   For example, expect the RZ57 to write about

   	8K * 35K / (35K + 8K) * 60/s = 391 KByte/s

   (You can speed up writes with a 1:2 interleave (skip each other 8K block),
    but you loose badly on reads, if you have multiple drives on one controller
    (tested with Fujitsu M2266).)

2) FTP is faster than NFS under the above mentioned conditions.

Hope it helps,

Stefan
-- 
 Stefan Esser, Institute of Nuclear Physics, University of Cologne, W. Germany
 se at ikp.Uni-Koeln.DE                                            [134.95.192.9]