5.2-rel NFS lockup and networking performance

Harald Schmalzbauer h at schmalzbauer.de
Mon Jan 26 09:32:26 PST 2004

On Monday 26 January 2004 13:10, Harald Schmalzbauer wrote:
> Dear developers,
> I just upgraded one of my servers from 5.1 to 5.2.
> Now when I dd from a linux box on a nfs-mounted 5.2 testfile writing 100kKb
> takes about 5 Minutes because the machine repeatedly "locks up". It seems
> every disk access is blocked for a while. (on the linux(debian woody) box:
> "dd if=/dev/zero of=/mnt/nfs/testfile bs=1k count=100000")

Dear coders,

I hate replying myself but I think it's neccessary.
The "lock up" problem is a bit more complex.

Like described I do the following on the linux box:
dd if=/dev/zero of=/mnt/nfs/testfile bs=1k count=100000

Now the first time it finishes ok (about 3.5Mbyte/s)
But when I repeat it takes up to 5 Minutes to finish since the FreeBSD machine 
seems to be locked up.
In fact, the FreeBSD machine is still accessable via the console. Also ICMP 
(ping) is working fine (from and to the FreeBSD box)
Existing ssh connections are also locked.
But I can setablish a second ssh handshake, I get the keyshandshake and enter 
my password (while the network seemed to be locked) but then don't get any 
After some minutes when the machine relaxed every connection is fine again and 
the newly created ssh connection establishes with the shell.

I don't know how this can be, but if someone has an idea what to debug, let me 
Regrettably this box is my strongly needed production fileserver, so tommorrow 
I'll give up on 5.2 and go back to 4.9

Best regards,



> But not only that NFS is broken with linux (I can do the same from my
> 5.2-current without locking up the 5.2-rel machine), also the performence
> is even more awful than with 5.1. Max transfers are about 4.5Mbyte/s and
> with samba I can get 3.5Mbyte/s. On the same machine with 5.1 it was about
> 8Mbyte/ s for NFS and about 5.5Mbyte/s for samba.
> I think I'll have to switch back to 4.9 since I can remember having had
> more than 9Mbyte/s even for samba with much older hardware arround FreeBSD
> 4.4. Can anyone confirm that 4.9 is still performing like this?
> Does anybody know about this NFS bug and this really weak networking
> performance?
> Best regards,
> -Harry
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