Backups seem like such
straightforward things: You take all the files that exist on a computer,
and you make copies of them somewhere else. In the case of Windows Home
Server backups, however, there’s a lot more going on under the hood.
This section provides you with a few notes that give you some idea of
the efficiencies and power that Windows Home Server implements.
Single Instance Storage
Unlike almost every other backup system, Windows Home Server does not back up at the file level (by, say, storing copies of files on the server). Instead, it backs up data at the cluster
level. (A cluster, you’ll recall, is the fundamental unit of storage in
the file system. That is, every file is really a series of clusters,
each of which is usually 4KB.) When Windows Home Server backs up a file,
it performs a cluster-by-cluster check to see if the same data has
already been backed up. If it finds an identical cluster already on the
system, it doesn’t include the redundant cluster in the backup. Instead,
it leaves the existing cluster on the system and makes a note about
which files that cluster belongs to. This technology is new to Windows
Home Server, and it’s called Single Instance Storage.
Note that this applies not just to the backups for a single computer, but for every
machine on the network. For example, suppose that a popular song
resides on your computer and on two other computers on your home
network. If your computer is the first to be backed up, Windows Home
Server will include the song in that backup. When it backs up the other
two computers, it will see that song on each one, but it won’t add the
redundant data to the backup.
You might think the space savings generated by
cluster-level backups will be minimal because, after all, how many songs
(or whatever) do multiple computers have in common? However, remember
that Windows Home Server doesn’t just back up your data. It also backs
up the %SystemRoot% folder, which contains the Windows system
files, many of which are identical across multiple machines (depending
on the versions of Windows each is running). It also backs up the %ProgramFiles%
folder, so popular applications such as Microsoft Office and Internet
Explorer also have lots of common files across the network. As a result,
the storage space used by the backups on Windows Home Server is a mere
fraction of the size of all the original files put together.
No Backup Types
Other
backup systems muddy the waters by offering numerous backup types:
Full, Incremental, Differential, Daily, and so on. Part of the
reluctance many people have to setting up a backup regimen is trying to
figure out the differences between these various types.
Windows Home Server does away with all that by having
no backup types. Instead, Windows Home Server’s backups use a simple
two-stage system:
For a computer’s first backup, Windows Home
Server backs up everything on the machine (with a few exceptions, as
you’ll see a bit later).
On subsequent
backups for the same machine, Windows Home Server only backs up data
that has been added or that has been changed since the last backup.
This sounds like an incremental (or is it differential?) backup, but that’s not the case. Instead, Windows Home Server treats every
backup as a full backup. So even if Windows Home Server only had to
back up a single file last night, if you look at that backup, you see
all your files. In other words, with Windows Home Server, you never run
into the situation where you need to restore one file from yesterday’s
backup, a second file from last week’s backup, and so on.
The other (not insignificant) advantage to this
backup strategy is that, although a computer’s initial backup may take
several hours, subsequent backups for that machine may take just a few
minutes.
Caution
To avoid an extremely long initial backup for a
computer, make sure that the machine has a wired connection to the
network. Even a 100Mbps wired connection is twice as fast as the typical
54Mbps wireless connection, and gigabit wired connections are closer to
20 times faster. Of course, that’s assuming your wireless connection
can even achieve 54Mbps, which is rare due to interference, shared
bandwidth, and so on.
Smarter Backups
Single Instance Storage is a pretty smart technology,
but Windows Home Server also implements a few other features for
intelligent backups:
To avoid conflicts, Windows Home Server never
backs up more than one computer at a time. When the backup time comes
around (the default time is midnight), Windows Home Server puts the
network clients in a queue and backs them up one at a time. Even if you
initiate a manual backup during that time, Windows Home Server still
puts that machine in the queue.
Windows
Home Server backs up the entire computer by default, but it doesn’t back
up every last file. Intelligently, it avoids unnecessary files, such as
the paging file (used by Windows to swap oft-used data to disk rather
than having to retrieve it from
its original location); the Recycle Bin (where Windows stores your
deleted files); the hibernation file (where Windows stores the current
contents of memory when the system goes into hibernation mode); and file
system shadow copies (the previous versions of files and folders
maintained by Windows).
If a computer is
in Sleep or Hibernate mode when the scheduled backup time occurs,
Windows Home Server pings the computer to let it know that it’s time for
backup, and the server puts the machine into the queue. When the backup
completes, Windows Home Server tells the computer to put itself back
into Sleep or Hibernate mode. For notebooks, this only happens if the
computer is running on AC; if it’s on batteries, the machine skips the
“wakeup call” to avoid using too much battery life during the backup.
Tip
Windows Home Server only wakes up the computer if you
enabled that option during the Windows Home Server Connector setup
process.
If you want to change whatever option you chose during setup, open
Launchpad, click Backup to open the Backup Properties dialog box, and
then use the Automatically Wake This Computer check box to set the state
you prefer.
Client Computer Backup Retention
Some backup systems accumulate backups until there’s
no space left for new ones! Windows Home Server’s Single Instance
Storage technology means that this is less likely to happen. However,
storage is always finite, so even Windows Home Server’s backups can’t
accumulate indefinitely. Fortunately, as part of Windows Home Server’s
commitment to a fully automated backup system, even the process of
removing old backups happens behind the scenes. This is called Client Computer Backup Retention,
(it was called Automated Backup Management in previous versions of
Windows Home Server), and it means that Windows Home Server deletes old
backups after a preset time has elapsed.
For dedicated tinkerers, you can customize the frequency with which Windows Home Server removes old backups.
Improvements to Client Backups in Windows Home Server 2011
The client backup system in previous versions of
Windows Home Server was excellent, but not perfect. For example, you
couldn’t protect client PC backups by including them with the server
backup, and the wizards used to exclude folders (as well as choose files
and folders for recovery) were a bit clunky to use. In Windows Home
Server 2011, Microsoft has addressed these and a few other issues to
improve client backups:
Backup backups— Windows
Home Server introduced backups of the server in Power Pack 3, but those
backups didn’t include the database of backups associated with each
network computer. That shortcoming has been rectified in Windows Home
Server 2011, which now gives you the option of including the client
computer backups in the server backup.
Easier folder exclusions—
In previous versions of Windows Home Server, excluding a folder from a
client’s backup was a bit of a chore, particularly if you had multiple
folders to exclude. Windows Home Server 2011 makes this much easier by
providing standard check boxes for each folder, so you exclude a folder
simply by deactivating its check box.
Backup resume—
In previous versions of Windows Home Server, if a backup was
interrupted, it just failed, and a completely new backup wouldn’t start
until the next scheduled backup time. Windows Home Server 2011 now
tracks the client backup process, and if the backup is interrupted for
any reason (for example, losing the network connection), Windows Home
Server 2011 resumes the backup from where the interruption occurred.
Support for Mac clients— Windows Home Server 2011 adds support for Time Machine backups, so you can back up your Mac computers to Windows Home Server.
Easier file and folder recovery—
Windows Home Server 2011 comes with a new restore wizard that makes it
much easier to choose individual files and folders to restore from a
backup.
USB client recovery key—
You can now use a USB flash drive to create a bootable computer
recovery key. If you can no longer boot a client PC, you can boot to its
recovery key and then restore the client from a Windows Home Server
backup.
