21.5. Tracking for Multiple Machines
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## 21.5. Tracking for Multiple Machines

Contributed by Mike Meyer.

If you have multiple machines that you want to track the same source tree, then having all of them download sources and rebuild everything seems like a waste of resources: disk space, network bandwidth, and CPU cycles. It is, and the solution is to have one machine do most of the work, while the rest of the machines mount that work via NFS. This section outlines a method of doing so.

### 21.5.1. Preliminaries

First, identify a set of machines that is going to run the same set of binaries, which we will call a build set. Each machine can have a custom kernel, but they will be running the same userland binaries. From that set, choose a machine to be the build machine. It is going to be the machine that the world and kernel are built on. Ideally, it should be a fast machine that has sufficient spare CPU to run `make buildworld` and `make buildkernel`. You will also want to choose a machine to be the test machine, which will test software updates before they are put into production. This must be a machine that you can afford to have down for an extended period of time. It can be the build machine, but need not be.

All the machines in this build set need to mount `/usr/obj` and `/usr/src` from the same machine, and at the same point. Ideally, those are on two different drives on the build machine, but they can be NFS mounted on that machine as well. If you have multiple build sets, `/usr/src` should be on one build machine, and NFS mounted on the rest.

Finally make sure that `/etc/make.conf` on all the machines in the build set agrees with the build machine. That means that the build machine must build all the parts of the base system that any machine in the build set is going to install. Also, each build machine should have its kernel name set with `KERNCONF` in `/etc/make.conf`, and the build machine should list them all in `KERNCONF`, listing its own kernel first. The build machine must have the kernel configuration files for each machine in `/usr/src/sys/arch/conf` if it is going to build their kernels.

### 21.5.2. The Base System

Now that all that is done, you are ready to build everything. Build the kernel and world as described in Sekcja 21.4.7.2, "Compile the Base System" on the build machine, but do not install anything. After the build has finished, go to the test machine, and install the kernel you just built. If this machine mounts `/usr/src` and `/usr/obj` via NFS, when you reboot to single user you will need to enable the network and mount them. The easiest way to do this is to boot to multi-user, then run `shutdown now` to go to single user mode. Once there, you can install the new kernel and world and run `mergemaster` just as you normally would. When done, reboot to return to normal multi-user operations for this machine.

After you are certain that everything on the test machine is working properly, use the same procedure to install the new software on each of the other machines in the build set.

### 21.5.3. Ports

The same ideas can be used for the ports tree. The first critical step is mounting `/usr/ports` from the same machine to all the machines in the build set. You can then set up `/etc/make.conf` properly to share distfiles. You should set `DISTDIR` to a common shared directory that is writable by whichever user `root` is mapped to by your NFS mounts. Each machine should set `WRKDIRPREFIX` to a local build directory. Finally, if you are going to be building and distributing packages, you should set `PACKAGES` to a directory similar to `DISTDIR`.

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21.4. Rebuilding "world" | Spis treści | Część IV. Komunikacja sieciowa

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