While I was away in the US (naturally), my house suffered a long powercut. So long that crimson forgot its electronic serial number again.The backup plan swung into action, requiring my loving family to boot the reserve server, chrome.
As usual, the backup plan was not trouble free. Apache did not
start up. I think this was because the resolv.conf file
still pointed at crimson at the time apache started. It wasn't
until a later, local script detected that crimson was not up that
the resolv.conf was munged to point at localhost. The only
clue to this was the message Alarm clock on the dmesg
output. However, as I could ssh to chrome, I could start Apache
manually.
Once back home, I decided to fix this problem by always using
chrome's DNS, that is by putting 127.0.0.1 as the first
entry in resolv.conf. However, I discovered this
change had a bad effect on the mounting of NFS volumes at boot time.
Since the DNS service was not up by the time the filesystems were
mounted, as defined in fstab, the NFS mount of the home
directory on crimson failed, with the following message printed
every 60 seconds on the console until Control-C was hit.
[udp] crimson - RPCPROG_MNT RPC: Port mapper failure - RPC : Timed out
If fact, I was puzzled as to how chrome had managed to get itself fully booted when brought up with crimson down. When I had tested chrome's ability to boot in the absence of crimson, I'd done it by unplugging the ethernet cable. The NFS mount had aborted with:
mount_nfs: crimson: hostname nor servname provided, or not known
Obviously, this was not a good test; FreeBSD behaved differently if there was no network connection as opposed to no server. Despite trying to re-create the conditions of the original problem, I could not get chrome to boot fully without manual intervention (Control-Cing the NFS mount on the console). I am baffled as to how it booted when I was in the US.
I considered not bothering with the NFS mount, as I didn't make much
use of it on chrome. Ignoring such defeatist thinking, I decided to
use the -b (background) flag, but in conjunction with the
new 'late filesystem' feature of FreeBSD 6.2. By marking a
filesystem as late in the fstab file, it would not be
mounted until after local applications (including named). By also
putting in a retry count of one, I would be able to boot whether or
not crimson was up.
The NFS mount line in the fstab file now looks as follows:
crimson:/home/stuff /mnt/crimson nfs rw,-b,-R1,late 0 0
