[ENBD] 2.4.30 problems with big file transfers (1 GB)

[Peter T. Breuer]

"A month of sundays ago ckoepp wrote:"
> Client: 
> Is a Pentium 3  700MHz with Intel Ethernet Pro 100 NIC.
> Debian Woody and at first a self compiled Kernel 2.4.18 and later (during my tests) I changed to 2.4.20.
> 
> Server1: 
> Celeron 366 MHz with the same NIC.
> Suse 7.3 Distribution
> 
> Server2: 
> Pentium 1  133 MHz with the same NIC.
> Debian Woody and a self compiled Kernel 2.4.20.
> 
> Reading a 1 GByte File from the server1 works fine: Transfer Rate about 5.5 MB/s. The HUB utilization scale goes up to 80 percent.
> Writing  the same file back to the server: Transfer Rate about 500 kB/s. The HUB utilization scale goes only up to 10 percent - usually it's lower.

This is usually an artifact of the VM or file system on the server. If
you can turn off caching on the server, you should find the effect goes
away.

> The last thing I did -  I tried NBD Version 2.4.29 and everything works fine, reading and writing works nearly with the same speed. 

Oh, well that is a problem, then. Are you SURE that this is repeatable?

> So I think there is a problem on Version 2.4.30 - any ideas?

Not necessarily a problem. What happens if you use -w 0 (and/or read
your logs!) on the server?

Peter