Installing 2.11BSD: Part II

With the root filesystem up and running, the rest of the system could be installed. The distribution splits this into three tar files, the first being the binaries and utility files of the /usr filesystem, the other two being the source code subdirectories. I wasn't planning on transfering 45MB of sources over the serial port, so the first file would be fine for now. The problem is that the freshly installed BSD system of course doesn't support the virtual tape set-up. Niether does VTServer provide any means to extract a tar file straight to a new filesystem - remember that root was in dump format. Extracting /usr would therefore have to be done a little differently...

I looked into the vct External link program, a client for VTServer that can pull files over to the PDP-11's filesystem. The problem here is that you also need some way to transfer vtc to the PDP-11 in the first place. The current version is also apparently limited to 9600 bps, meaning it'd take about half a day to get just this one tar file transfered.

So, I thought, how about using VTServer to dump a tar file straight onto a raw disk? After all, I had 70MB of space which was currently just sitting there and could be put to good use a temporary storage. Unfortunately, BSD's tar didn't really like working on raw disks, complaining about bad checksums. Also, the VTServer copy went a bit weird after spending 3 hours writing to disk. I suspect some counter rolled over as the periodic status reports went back to "100K sent" after 32700K had been pumped over.

I ended up making a couple of special disk images in the SIMH PDP-11 emulator (on which I'd done a full 2.11 installation) which I could then transfer over to the PDP-11 using VTServer's stand-alone copy program. Each contained one partition with a filesystem just big enough for the files I wanted to transfer. As long as you don't write past the partition, the resulting disk image will also stay small. The first image contained the compress program from /usr/ucb. The other had a compressed tar archive of the /usr fileystsem I'd extracted to a disk on the emulator thus:

# mt rew
# mt fsf 6
# dd if=/dev/rmt12 of=usr.tar bs=10240
# compress usr.tar

You could probably do this more efficiently with a pipe, but I wasn't in any hurry. With the combination of compress and the archive on disk, I could get the contents of /usr onto the PDP-11 whilst only transfering about 20MB of data over the serial line. The trade-off is of course that the extraction process takes that little bit longer, but at least I was confident I wasn't going to hit any limits transfering the disk image. Extracting the actual contents is simplicity itself:

# cd /usr
# uncompress -c /mnt/usr.tar.Z | tar xpf - &

Putting the command in the background means you can keep track of the progress with ls and df, which is handy as it does take a while. The same procedure was repeated for the kernel sources and header files but, seeing as this is a relatively small tar archive, this wasn't compressed.

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