Enquiring Mind said:
Many thanks for your further clarifications. This is uncharted territory
for me, so here are some initial thoughts about the issues, which have
probably very simple answers.
You seem to be advocating a disk-orientated back-up strategy as opposed to
a file-orientated back-up strategy. The disk-orientated back-up strategy
seems to mean that the data in every sector of a source disk has to be
compared with the corresponding sector of a back-up disk - perhaps all 80
GB of them - and the sectors that are different copied. (It may, of
course, be quicker to forget about comparing the sectors and just copy all
the source sectors to the backup sectors.)
In the alternative file-orientated strategy, only file records read from
the OS's file table need to be compared, and only the files modified
since the previous back-up need to be copied, perhaps just a few hundred
MB. Which files need to be copied can be determined by comparing just the
file's size and time stamp when last modified (or, more comprehensively,
comparing the full file table record) - there's no need to read and
compare every byte of the file in order to determine whether or not the
source file has changed with respect to the corresponding file in the
back-up store.
This suggests that for daily backup purposes, the file-orientated approach
is much more efficient, even though it doesn't necessarily back-up all
system files, because only the file directories from each disk need to be
compared, and only files that have changed need to be actually copied. The
disk-orientated back-up approach seems to be more appropriate just before
installing some new software or replacing the hard drive of the computer,
or making any other major changes to the system, as it records the full
state of the disk.
Let me now return to security issues. With a disk clone, the disk clone
contains exactly the same file data as in the source disk, but there might
be a significant difference. Whilst in the source disk files are private
to the users that possess the necessary permissions, in the clone they
might become public/shared, otherwise how could the files be read when the
EHD is connected to another computer? This means that while the backup
drive is connected to a computer via the USB connection, a piece of
malware, or an ill-intentioned computer user, could read back-up copies
of files which would be inaccessible to it/him in the source disk and
steal information. To prevent this the backup copy would have to be
integrally encrypted using a non OS-dependent password. Encrypting all the
sectors on a disc slows down an already time-consuming operation, and
since there may be many empty sectors in the source disk, cracking the
encrypted disk copy would be easier than cracking individually encrypted
files.
In the file-orientated backup strategy, all files that have been modified
since the previous backup could be read from the source disk, encrypted in
memory using a password specific to the back-up (i.e. not the key
specific to the currently logged in user, thereby avoiding any NTFS
encryption issues), and then saved to the backup disk. Since the files in
the backup disk are all encrypted, it matters not that they become shared.
They can be recovered to any disk, provided that the correct backup
password is supplied. Of course, any files that in the original source
disk had NTFS encryption would not be readable after recovery, unless the
user took the care to back up the certificate as well as the file.
So the question is: do the various commercial back-up tools on offer
address these issues? And what about the back-up and synchronization
software that usually comes with the external hard drive?
Regards,
EM
EM:
Setting aside your comments & query re security/encryption issues as they
bear upon the disk (partition)-cloning & disk-imaging processes we have been
discussing, I really don't know if I have anything more substantive to offer
than I provided in my previous posts.
Working with thousands of PC users over the years it has been abundantly
clear to us that it is crucial that a substantial number of these users
would be well served by establishing & maintaining a comprehensive backup
program - a program that would not only back up their personal data, but one
that would also back up their OS and all programs & applications - in
effect, a program that would create a precise copy of their day-to-day
working HDD(s). So that if & when that day comes that their system becomes
dysfunctional because of a corrupt OS resulting in an unbootable HDD or the
HDD itself becomes defective, they would have the means to effectively &
reasonably quickly restore their system(s) to a bootable, functional state.
In our view a disk-to-disk (partition-to-partition) cloning program is an
effective tool in meeting that objective. We've continually searched for a
program that was effective (it did what it was supposed to do),
straightforward in design, and easy-to-use even for an inexperienced user.
We've used & experimented with a variety of such programs over the years and
found the Casper 5 program met those objectives. Together with its
"SmartClone" technology (of which I've already commented on in some detail)
we've found this program superior to the others we've used over the years.
When one peruses this newsgroup and similar ones dealing with users'
problems, how many times a day, a week, do we see these types of plaintive
pleas for help?...
"Helllllp! My hard drive apparently died. How do I get my data back?", or,
"I just installed SP3 and now my computer doesn't even boot", or,
"I made that registry change XYZ suggested and now I'm getting weird
messages from Windows", or,
"I installed the latest update from Microsoft and now my anti-spyware
program has been trashed", or,
"I installed that new Super-Duper Anti-Malware program and now all I get is
a black screen", or,
"All of a sudden I'm getting that dreaded BSOD and my system won't. How can
I save my precious photos?", or,
"After I just installed that beta copy of Windows 7 I get this funny message
from Windows that I have to close down my system and now nothing works", or,
"My hard drive was making funny noises and now nothing happens when I push
the power button on my 'puter"...
The list goes on & on, does it not? Does an hour, a day, a week pass where
we don't see the above "cries of distress" and similar pleas for help?
In so many cases the problem would have been a non-problem had the user made
a precise copy of his or her then-functional system *prior* to installing a
major program on their machine or making some major configuration change in
their otherwise perfectly-working system. This can be relatively easily
achieved through the use of a disk-cloning program such as the Casper 5
program which we prefer. So that in the event of a catastrophe - minor or
major - the system can be easily restored to its previous functional state.
When all is said & done, that is the sum & substance of the value of a
disk-cloning program.
Simply stated, a *desirable* disk-cloning program will allow the user to
restore his or her system easily & quickly when their system fails because
of a defective HDD or the system has become unbootable & dysfunctional
because of data corruption from malware, unwise configurations, or other
causes.
But as I previously indicated, the chief reason we prefer the Casper 5
disk-cloning program (aside from its simplicity of operation and general
effectiveness in carrying out the disk (partition)-cloning operation) is
because of its rather extroardinary ability to *speedily* clone the contents
of one drive (or partition) to another drive
(or partition) when the program is used on a frequent basis. As I mentioned,
Casper incorporates what it calls its "SmartClone" feature. The program has
the happy capability of detecting *incremental* changes in the source
drive's data since the *previous* disk-cloning operation. By so doing and
then taking only those incremental data changes into account, the amount of
time the program needs to complete subsequent disk-cloning operations is
significantly shortened (as compared with other disk-cloning programs). Keep
in mind that the resultant clone is a complete clone of the contents of the
source HDD - not merely an incremental "file".
As a result of this feature there is an enormous incentive for users to
backup their systems on a more-or-less current basis knowing that the
expenditure of time in doing so will be relatively slight. Heretofore this
has been a major problem with disk-cloning programs (in terms of *routinely*
using the program as a comprehensive backup system) because each time the
disk-cloning operation was undertaken it was considered by the program to be
a "fresh" operation and therefore took a considerable amount of time to
complete the cloning operation. So many, if not most, users would balk at
using the disk-cloning program on a frequent basis because of that
expenditure of time to undertake the disk-cloning operation.
Obviously there are different approaches one can take with respect to
selecting a backup program (or programs) depending on one's interests. In
many cases the user is unconcerned with backing up their OS and programs &
applications. Their only interest is backing up personal data. Or many users
prefer the disk-imaging process rather than the disk-cloning process, such
as you find in programs such as Acronis True Image or Symantec's Norton
Ghost, etc., as a comprehensive backup tool. We encourage users to
experiment with various backup programs & approaches to determine which ones
will best serve their needs. Especially when trial/demo versions of these
programs are available.
Based on our experience most of the backup programs that are provided with
commercial USB external HDDs are geared toward backing up data created by
the user. They are (by & large) not designed as comprehensive backup
programs such as the kind of disk-cloning/disk-imaging programs under
discussion. While some of them do have this latter capability we have found
them for the most part to be torturously slow in carrying out the operation
and not particularly suited as a comprehensive backup strategy that will be
used routinely & frequently by the user. On the other hand they well might
meet the needs of a certain body of users.
By & large the kind of programs we've been discussing are not geared toward
maintaining security of data. That's a completely different subject to be
explored by a user such as yourself since this is (apparently) an important
consideration in your selection of a backup program. As I'm sure you know
there are a multitude of programs available dealing with this special area.
Anna