barcaroller <> wrote:
> "David Empson" <> wrote ...
>
> > Not easily. There is no mechanism to partition the internal drive in a
> > Time Capsule. This means you are limited to working with files on a
> > single file system.
>
> Ah, that's important to know. So, just to clarify, I can't just format and
> set up filesystem partitions on a Time Capsule hard-drive, regardless of
> whether I'm using Time Machine or not. Is that correct?
Correct. The only tools available in Airport Utility for manipulating
the internal drive in a Time Capsule are to erase it, verify/repair it,
and back up or restore tofrom an externally connected drive.
You can't access the Time Capsule drive using Disk Utility's volume
maniupulation tools, so there is no way to partition a Time Capsule's
internal drive.
(Some people have apparently proved you can partition a Time Capsule by
pulling it apart, removing the hard drive, connecting to a Mac to
partition it, then reassembling the Time Capsule, but the Time Capsule
is not designed to be opeend, so this will void your warranty.)
With an external drive connected to a Time Capsule or Airport Extreme,
you can connect it to a computer (temporarily) to partition it, then
move it back to the Time Capsule or Airport Extreme, where all of its
partitions are accessible.
> > To prevent Time Machine using all of the drive, the easiest solution is
> > to create one or more fixed size disk images, and use them to store any
> > incidental files you want to keep on the Time Capsule (which won't be
> > backed up by Time Machine).
>
> I don't know what you mean by fixed disk size images. Will you please
> elaborate?
You can use Disk Utility to create disk image files.
As far as the "host" file system is concerned, the disk image is just a
big file. When you mount the disk image, the operating system treats it
as a separate volume.
There are two major types of disk image: normal disk images and sparse
disk images.
Normal disk images are a fixed size. You specify the size when you
create the disk image (or it is determined from the size of a source
volume or folder if you instruct Disk Utility to create an image from
existing data rather than just creating an empty disk image). The size
of the disk image file will be a little larger than the size of the file
system it contains, due to overhead for the disk image file itself (plus
overhead within the contained file system, e.g. directories).
Sparse disk images are a variable size on the "host" file system. You
specify a maximum size when you create one, but they start out quite
small (in disk usage) and grow as you add more files to the file system
within the disk image.
A sparse disk image may be a single file (with a nominal maximum size
but only the used parts of the file actually having space allocated on
the host file system) or a "sparse bundle", which is a folder pretending
to be a single file (a general concept known as a "package") which
contains a large number of relatively small files (a few megabytes
each).
> > Another option would be to connect an external drive to the Time
> > Capsule. Use the internal drive for your Time Machine backups and the
> > external drive for incidental file storage (which won't be backed up by
> > Time Machine).
>
> Another option is to just get an Airport Extreme with an external hard-drive
> and have Time Machine backup to the internal drive. I assume Time Machine
> is smart enough not to fill up the internal system disk (I can't imagine
> Apple developers allowing that).
You assume wrong.
First, Time Machine doesn't let you back up to the same drive as the
source data, unless you override it. If you think about it, this is a
very bad idea: if your hard drive failed, you would lose all your
original data and all your backups. It doesn't matter if you are dealing
with one or multiple partitions - you should never use the same physical
drive as a backup for your source data.
Secondly, Time Machine doesn't care what drive you are using to do the
backups as far as its disk usage is concerned. If you were foolish
enough to store your Time Machine backups on your startup volume
(ignoring Time Machine's warnings about not doing that), the Time
Machine backups would eventually fill the entire volume and your system
would probably be unbootable because it wouldn't have space to store
temporary files and virtual memory swap files.
--
David Empson