Re: Setting up an external hard drive - partioning and sharing issues

Anna,

Thanks again for your exhaustive and instructive post. Please see some
further comments embedded in the copy of your post.

"Anna" <myname@xxxxxxxxx> wrote in message
news:eF4oeB5tJHA.4068@xxxxxxxxxxxxxxxxxxxxxxx



EM:
By & large I think you've covered the basic differences between
disk-cloning & disk-imaging as they apply to creating a comprehensive
backup system for one's PC.

Just a few comments...

With respect to the disk-imaging approach (referring to your numbered
items above)...
1. Keep in mind that while the *original* disk-image (Acronis refers to it
as an "archive") created by the user is a single file, presumably the user
will be subsequently creating *incremental* files ("archives") necessary
to maintain up-to-date backups of one's system. Both the original file
(archive) and subsequent incremental files will ordinarily be retained
until either they're used for recovery purposes or the user decides the
sheer number of them is too unwieldy to continue and simply "starts over"
by creating a new "original" disk-image backup, deleting the existing
files/archives in the process.

Thanks for the clear explanation. It's reassuring to know that it's not
necessary to create a new mammoth disk-image file at each back-up cycle.

While there's no need to create multiple partitions on the "destination"
drive to serve as the recipient of these disk-images, folders would
ordinarily be created to house the images from different "source" HDDs.

In any event, please do not attach too much importance to the issue of
creating partitions on the destination HDD either in terms of difficulty
or amount of time needed to do so. This is a very simple operation that
can be easily achieved through XP's Disk Management snap-in or using the
Casper 5 program during its disk-cloning operation.

It may be simple to do using XP's Disk Management snap-in , but I understand
that the data on the disk must be backed up beforehand because creating new
partitions using the snap-in deletes the files on the disk. Or is that no
longer the case?

2. With respect to the disk-image, there will (usually) be a certain
amount of compression provided by the program so that the resultant
file/archive will be somewhat smaller than the actual size of the contents
that are imaged. In the case of the Acronis program we have generally
found that this reduction via compression is somewhat in the order of
20% - 25%. So, taking your example, of 3 GB of contents being "imaged",
the resultant file/image would be about 2.5 GB or so.

But you've misunderstood this situation with respect to the disk-cloning
process. (Again, my comments refer specifically to the Casper 5
program)...

Again, using your example of an 80 GB HDD (or partition) that contains 3
GB of data, as I previously explained, the user could easily create a
partition on the destination drive *equal* to the size of the data being
cloned - in this case, 3 GB. Or, he or she could create a larger size to
anticipate future increases in the size of data subsequently cloned. The
choice of the size of the partition rests with the user, the *only*
limitation being that the partition must be of sufficient size to contain
the cloned contents.

This makes me wonder whether I have misunderstood what Casper does. I
thought that it creates a low level sector-by-sector copy of the source disk
on the destination disk without regard to the structure or meaning of the
data. But if we can clone a 80GB disk to a 3GB disk, this suggests that
Casper is not copying all raw data in the disk, but just the data in actual
files, since in the source disk the file data may be dispersed on sectors
that could be located anywhere on the disk (if the disk is highly
fragmented). So the low-level byte layout on the clone may be different to
that on the source. If Casper is backing up files only, this explains why
when Casper is doing an incremental back-up, it only needs to back up files
that have changed since the previous backup.

And, of course, there is no compression of data using the disk-cloning
process. A clone is a clone is a clone.

It is true that in the usual scenario - where a user has a single
day-to-day working HDD (which probably represents the overwhelming number
of cases) - that user will employ the "destination" drive (internal or
external) as the dedicated recipient of the cloned contents of their
source HDD and simply create disk-to-disk clones and not be concerned in
any way with partition manipulation. In your situation where you're
working with two different PCs and apparently desire a single USBEHD to
serve as the recipient of the data from each of those two PCs, obviously
the creation/manipulation of partitions is important.

In many cases we find that where a user is working with both a
laptop/notebook and a desktop machine they simply use two separate drives
to serve as recipients of the clones from each machine. Given the dramatic
decreases in costs for these devices over the past few years it's not a
terribly expensive proposition for many users to go that route.

3. See above re the compression issue.

4. Yes, you have it right. There's a "recovery" process that is necessary,
but it's not particularly onerous or too terribly time-demanding. In any
event, what is important is that the process be *effective*, not the
amount of time it takes to return the system to a bootable, functional
state. As I have tried to point out in my previous posts, it is the
routine *backup* operation that's important from an expenditure of (user)
time point-of-view. Presumably, in the vast bulk of cases, the user will
be performing scores, if not hundreds, of backup operations before a
recovery of the system will become necessary. It's this extroardinary
speed of the backup operation (cloning) that makes the Casper 5 program so
superior in my view. But as I have emphasized the program must be used
with reasonable frequency to achieve this advantage.

The rationale for backing up the whole system rather than just the user
settings and data seems to be that by so doing in the event of a disk
failure one can reboot directly from the backup disk and one is spared the
task of reinstalling all one's software and system settings. However, will
this really work? Some software programs use the serial number of the disk
as part of a license control system. So even though the restored files are
the same as on the original disk, the disk serial number has changed, so
some programs may not work without being reinstalled afresh.

5. Yes, I'm assuming you're referring to incremental disk-image files
(archives) here.

With respect to your observations re the disk-cloning process...

Yes, as I've previously indicated, should a user be primarily interested
in maintaining "generational" copies of his/her system at various
points-in-time, a disk-imaging program lends itself better to that goal.
While relatively few home PC users are interested in that objective, in
that they are exclusively interested in maintaining an up-to-date backup
of their system(s), many commercial entities require that capability for
obvious reasons.

While a disk-cloning program could be used to some extent for that
purpose, it would depend upon the volume of data to be cloned together
with the size (disk-space) of the destination drive(s). For example, we
know of a number of Casper 5 users who are interested in retaining 2, 3,
or 4 previous clones of their systems and in many cases this can be easily
accommodated given the enormous capacity of today's HDDs - both internal &
external.

May I again suggest, as I've done throughout this entire thread, the only
*real* way to determine which program best meets your needs is to
experiment with them. In the final analysis, only a "hands-on" approach
will determine what's best for you. Fortunately, many of these programs
have demo or trial versions available so you can gain at least some
understanding as to whether this one or that one will best serve you. And,
as you have discovered, there are a number of freely available programs
you can test out as well.

What I'm trying to impress upon you (and others) is simply this...

Don't rely on theoretical explanations (from me or anyone else) of what
this program or that program or this approach or that approach can do or
not do for you. Work with these different programs as best you can so that
you - and only you - will determine the appropriate approach/program
needed in your unique situation.
Anna
Good advice, but it is nevertheless prudent to understand what you are doing
before doing too much experimentation!

May I add another back up option to the disk-imaging and disk-cloning
options discussed so far? The third option is to simply maintain a parallel
copy of the source folder and file structure on the back-up disk (like
offline files between a laptop and a desktop).

This option offers the following advantages and disadvantages:
1) If the synchronization between the source and back-up folders is
performed by a specialised application, the files in the back-up folder may
be password protected and/or individually compressed, thus guaranteeing the
privacy of the content of a medium which gets no privacy protection
whatsoever from the computer, being an external device connectable to any
computer.
2) The synchronization application can minimise the number of files that
have to be copied during the backup operation by using the file's Archive
flag or Time Last Modified to determine whether or not it needs to be backed
up. This means that the time needed to complete a backup cycle may be no
longer than a couple of minutes even for a large number of files.
3) There's no need for partitioning the back-up drive. Partitions are in
principle a great aid, but limit flexibility to change source drives in the
future. The folders on the back-up device can grow in size without causing a
lot of disk activity. The same can't be said for the disk imaging option.
4) The owner of the back-up data can browse the file names in Windows
Explorer.
5) The files can be restored on folder or file basis.
6) Because the backup process never needs to delete mammoth archive files,
but only relatively small individual files, the disk should not become too
fragmented, and it may be defragmented relatively infrequently.
7) There is less wear and tear of the disk drives.
8) The disadvantage is that somebody could accidentally delete or modify
some of the files in the back-up folder, thereby rendering the back-up
folder no longer a true image of the source folder.

When I recently used the Windows XP Pro Backup utility to make a copy of
"All information on the computer", I was horrified to see that not only did
it back up all the files on the internal drives of the computer, but also
all the files on the external hard drive to which I was backing up (except
the back-up file I was creating, of course)! This meant that the monolithic
back up file also contained copies of all the previous back-up files on the
EHD, making it MUCH larger and more cumbersome than necessary! I suppose
this is the sort of thing that creates a market for third party tools like
Casper and Acronis True Image.

Regards,

EM


.

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