[Beowulf] network transfer issue to disk, old versus new hardware

[David Mathog]

Bogdan Costescu wrote:

> > Old:  Athlon MP 2200+, Tyan S2466MPX mobo, 2.6.19.3 kernel, 512Mb RAM
> 
> I used to have the exact same hardware as cluster nodes (but with dual 
> CPU, whether you also have duals is not clear from your post) 

These are single CPU machines.

> and 
> tried to convert 2 of them to small file-servers - same problem of 
> disk + network simultaneous activity. After benchmarking, I gave up - 
> this was almost 2 years ago and I don't have the exact numbers 
> anymore, but a single PIV 3GHz on a consumer-grade mainboard was able 
> to provide significantly better performance for the same task.

Was athcool running on these?  I've done some more benchmarking with
athcool on/off, and it changed the write speed for the dd generated
512MB file from just under 18MB/sec to 31 MB/sec.  Even with that
change, there is clearly something else going on in the network + disk
department, since the "expected sequential" rate only changes from
7.1 to 8.5MB/sec.  The "hdparm -tT" results were around 520MB/sec
cached reads in either case, but the timed buffered disk reads
went from 24MB/sec to 44MB/sec (both with large variances, but not
THAT large.)

Thankfully this is entirely irrelevant to those of you who have long
since retired these older Tyan systems. 

Regards,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech