Hardware Reference
In-Depth Information
The WOL trick covered earlier generally doesn't work across the Internet because it is a Wake on
LAN
feature.
And even if your machine isn't behind a router or modem that filters out such packets, something else generally will
be. If it's vital for your home machine to be powered for as long as possible and your machine cannot be made to boot
when the power is connected, then you can employ an NSLU (hacked as shown in Chapter 2) as a bootstrap to issue
WOL commands to your various server machines.
Backups
There are only two important things to say about backups:
u
Do them.
u
Test them.
Everything else is mere details.
The first detail is whether these should be held on-site, that is, at home, or off-site in a remote location, such as
a colocated server or hired virtual machine. In an ideal world, you would adopt both. Keeping them off-site helps
minimize loss caused by local problems, while on-site backups are useful for data that you cannot possibly store
elsewhere, such as configuration scripts and network plans that you'd need to rebuild the HA system should there be
major failure.
The next detail is what data actually
needs
to be backed up. Again, in an ideal world, that would include
everything on every machine in the house. In reality, you have to consider the cost of replacing the data and the time
necessary to perform the backup. This usually boils down to anything that you've personally created, such as the
following:
u
Photographs
u
Letters
u
Program code
u
Artwork
u
Digital video
u
Music
Each member of the family will have their own list that they will be responsible for. You, as the HA administrator,
will also want to back up the server configurations.
From here you can decide on the technology needed to carry out this task. Programmers will already be aware of
source control tools, such as Subversion (
http://subversion.tigris.org/
) or Git (
http://www.git-scm.org
), and
will be advocating their use. For the uninitiated, these tools don't just keep a copy of the latest version; they keep data
to recreate copies of
all
the versions you've ever created, allowing you to go back in time to see what you wrote last
week and why that does (or doesn't) work! For the most part, it's a good choice for code and system configurations
because, as a developer, you have the mind-set necessary to perform the necessary update-merge-commit cycle at
every juncture. However, with some coaxing, most family members will become au fait with it. Accessing the files
requires a Subversion client, and there are several to choose from (such as TortoiseSVN or SmartSVN) that also have
versions for Windows, eliminating that support headache. This also gives family members the ability to access their
files from outside the home with no extra effort or software. On the downside, however, you will have to educate the
family that word processing documents are usually stored in a binary format and, as such, are next-to-impossible to
merge together if they change the same file at home and at school. Nor is it particularly efficient to use source control
for large files that change often, such as raw Adobe Photoshop images.
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