By having more and more devices around at home, it makes sense to keep all data in one place. I have a server for longer time, that runs a samba server, nfs file server and is acting as host for VirtualBox and Xen virtual machines. I had finally time to complete another phase of this “move everything to server”, by using a central home directory for all the clients.

The experiment was so far not completely successful as the writing speed towards the server is horribly low. I made the following experiments

1. Measured the ip speed with iperf in both directions between the client and server.

on the server:

xxx@yyyyyyyyy:~$ iperf -s
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
[ 4] local port 5001 connected with port 56444
[ 4] 0.0-10.0 sec 753 MBytes 630 Mbits/sec

on the client

uuuuu@qqq:~$ iperf -c
Client connecting to, TCP port 5001
TCP window size: 16.0 KByte (default)
[ 3] local port 56444 connected with port 5001
[ 3] 0.0-10.0 sec 753 MBytes 631 Mbits/sec

so the transfer rate is quite good (630Mbits/sec) for a Gbit card on both side as the server has a slower PCI.

2. Copied a 100MByte file from the server to the client, it took 1.6 sec

3. copied a the same 100MByte file from the client and it took 60sec!!! so 10 times slower!!! Cannot beleive….

Here is the line from /etc/fstab for the /home folder /home nfs4 auto,rw,nodev,sync,_netdev,noatime,proto=tcp,retry=10,rsize=32768,wsize=32768,hard,intr 0

4. By changing the sync parameter to async there was some significant improvement, but still far from perfect… copying from the server remained 1.6 sec, and copy to the server dropped to 3.6 sec. The same copy on the server, locally takes 1.7 sec.

This means that copying through nfs is twice slower than a local copy without having network bottleneck.

4. Copying 1000 files of 100kbyte from server to client took ~3sec, but back to the server 45secs!!!!! This is really painful. This made it clear, why programs like firefox slowed down since the nfs home. Firefox writes several small files quite often, so …

5. And now some comparison about (half) alternatives. Copying with scp the same 1000 files to the server took 12secs, so almost a quarter of the time spent with nfs.

Important to mention that there is no router between the computers, they are connected with a cat6 cable (gigabit ethernet).

Any suggestion if this copy time could be decreased?