Wednesday, May 12, 2010

Jumbo Frames and Xen don't mix well

It seems that while the pethN and ethN in a dom0 can be set to support jumbo frames the bridge that connects them cannot. Some symptoms are ssh works but scp does not, pings the size flag set to overflow the standard 1500 mtu fail, ifconfig xenbr0 mtu 9000 fails. This was tested with xen 3.1 and rhel5.

Thursday, April 1, 2010

Copying dumps from Postgres to MonetDB

When moving bulk data from postgres to monetdb you can use the psql \copy directive and the mclient copy like so:

\copy gftp_packets to 'my dump file' with csv
copy into gram_packets from 'my dump file' delimiters ',','\n' ;

Booleans don't work, but a little python will fix it up:

fin = open('my dump file', 'r')
fout = open('my new dump file', 'w')
falserep = (x.replace(',f,',',0,') for x in fin)
truerep = (x.replace(',t,',',1,') for x in falserep)
for line in truerep: fout.write(line)

I was too lazy to fix the problem with successive booleans, so I just rinsed and repeated until all the t's and f's were 0's and 1's.

Friday, February 12, 2010

Google Fiber for Communities

If you are a Bloomington area person please let me know. I am trying to organize a bid for the Google Fiber for Communities experiment.