Remote Tape slow....

Ralf Folkerts ralf.folkerts at
Fri Nov 10 08:11:30 UTC 2006


I recently replaced an old DDS-II Tape with a not so old AIT-Tape in one 
of my FBSD-Boxes. However, access via RMT is really slow :-(

When I perform a local dump of the machines that hosts the drive I get 4 
- 6MB/s throughput. I get roughly the same speed, when I move the Tape 
to one of the other machines and perform a local dump.

However, when I set "RSH=/usr/bin/ssh" and then dump to 
user at tape-machine:/dev/sa0 (I didn't change any of the other 
dump-Parameters like Blocksize etc.) I get a speed of ~1MB/s.

I tried this both with good old 3Com 3C905TX(100MBit) and DLink DGE-530T 

The Drive is atached to an Adaptec 2940UW, the "normal" Machine that 
Hosts that Drive is a PIII/733MHz Box with 512MB RAM.

During the dump none of the machines really show up with Load; they are 

Is this the expected behaviour of RMT? I thought I could expect (nearly) 
the speed of a locally atached Drive. Or is there something to tune so I 
get better throughput?

I already searched the Lists, Manual and G* but ddin't find a real hint :-(

Would be great if I could speed this up...


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