disk mirroring

[Talal Itani]

I use my XP Computer to run a small business. I want to create an exact
image of my C drive. Which software do you recommend? Can the IDE drive I
mirror to reside in an external USB case?

Talal Itani

 

[Pegasus \(MVP\)]

I use my XP Computer to run a small business. I want to create an exact
image of my C drive. Which software do you recommend? Can the IDE drive I
mirror to reside in an external USB case?

Talal Itani

"Mirroring" refers to the on-line process of maintaining
a near identical copy of a disk partition. This facility is
not available under Windows XP. You can either to it
with a hardware mirror or with an off-line imaging process,
e.g. with Acronis True Image.

 

[Shenan Stanley]

I use my XP Computer to run a small business. I want to create an
exact image of my C drive. Which software do you recommend? Can
the IDE drive I mirror to reside in an external USB case?

What is your reasoning behind making an exact mirror (live mirroring I am
assuming?)

I think you would be much better off backing up the important data (you
could even do this in addition to a hardware RAID (mirror)).

You could also using an imaging software to automatically and periodically
make full images of your computer to an external piece of hardware.

However - anything you do not also take off-site on occassion may still come
back to haunt you later.

 

[Dave]

I use my XP Computer to run a small business. I want to create an exact
image of my C drive. Which software do you recommend? Can the IDE drive I
mirror to reside in an external USB case?

Talal Itani

Mirroring is described here:
http://en.wikipedia.org/wiki/Redundant_array_of_independent_disks
See RAID 0+1.

What you apparently want is an on-hand clone from your description. In your
case regarding your potential solution, I would keep an updated image (not a
clone) on the USB drive. Keep a backup drive available to restore the image
to in event of the current hard drive failing.

 

[Talal Itani]

What is your reasoning behind making an exact mirror (live mirroring I am
assuming?)

I think you would be much better off backing up the important data (you
could even do this in addition to a hardware RAID (mirror)).

You could also using an imaging software to automatically and periodically
make full images of your computer to an external piece of hardware.

However - anything you do not also take off-site on occassion may still
come back to haunt you later.

I use the PC for business purposes. I backup my data, but I always worry
that my disk drive may fail. If the drive fails, I have to rebuild the
entire system, and that can take some time. If I have an image of the
drive, I can simply remove the broken drive, and install the new drive.

Maybe RAID is a better way to go, but I do not know much about RAID. My
mother board is and Asus P4PE with Raid 0 and 1 support.

 

[Talal Itani]

Mirroring is described here:
http://en.wikipedia.org/wiki/Redundant_array_of_independent_disks
See RAID 0+1.

What you apparently want is an on-hand clone from your description. In
your case regarding your potential solution, I would keep an updated image
(not a clone) on the USB drive. Keep a backup drive available to restore
the image to in event of the current hard drive failing.

Let me make sure I understand this correctly. A clone is an identical
drive. An image contains everything the drive contains, yet it cannot be
installed and executed, but it has to be brought in. I would run restore
from floppy disk, that brings everything from the image drive, into a newly
blank installed drive. Please correct me if I am wrong. Thank you. Which
software does that?

 

[Pegasus \(MVP\)]

Let me make sure I understand this correctly. A clone is an identical
drive. An image contains everything the drive contains, yet it cannot be
installed and executed, but it has to be brought in. I would run restore
from floppy disk, that brings everything from the image drive, into a newly
blank installed drive. Please correct me if I am wrong. Thank you. Which
software does that?

Acronis TrueImage (among others). And it boots from a CD, not
a floppy disk.

 

[Timothy Daniels]

Acronis TrueImage (among others). And it boots from a CD,
not a floppy disk.

If you want to clone the entire contents of the HD, True Image
is fine. If you want to clone a single partition from among 2 or more,
and perhaps put it among 1 or more existing partitions on another
HD, True Image can't do it (according to its documentation).
Utilities that *can* clone single partitions are Symantec's Ghost and
Future Systems Solutions' CasperXP. Done as single partitions,
more than 1 clone can be stored on a large capacity HD, and if
that archiving HD is connected (or on a slide-in tray), any one of
those archived clones can be booted up in seconds as a selection
from a multi-boot menu.

*TimDaniels*

 

[Timothy Daniels]

Acronis TrueImage (among others). And it boots from a CD,
not a floppy disk.

If you want to clone the entire contents of the HD, True Image
is fine. If you want to clone a single partition from among 2 or more,
and perhaps put it among 1 or more existing partitions on another
HD, True Image can't do it (according to its documentation).
Utilities that *can* clone single partitions are Symantec's Ghost and
Future Systems Solutions' CasperXP. Done as single partitions,
more than 1 clone can be stored on a large capacity HD, and if
that archiving HD is connected (or on a slide-in tray), any one of
those archived clones can be booted up in seconds as a selection
from a multi-boot menu.

*TimDaniels*

 

[Pegasus \(MVP\)]

If you want to clone the entire contents of the HD, True Image
is fine. If you want to clone a single partition from among 2 or more,
and perhaps put it among 1 or more existing partitions on another
HD, True Image can't do it (according to its documentation).

Only partly true. The OP can create an image file of the source
partition, the restore this image to the destination partition. It would,
of course, be nicer if the OP did not have to take this detour . . .

 

[Talal Itani]

Only partly true. The OP can create an image file of the source
partition, the restore this image to the destination partition. It would,
of course, be nicer if the OP did not have to take this detour . . .

What OP stands for?

 

[Pegasus \(MVP\)]

What OP stands for?

OP=Original Poster, i.e. YOU.

 

[Talal Itani]

OP=Original Poster, i.e. YOU.

Thanks. When I first posted my question, I was unaware of the two
techniques: 'cloning' and 'mirroring'. Now I know. I think mirroring is
the way to go for my case, since I can store multiple mirrors on the same
backup drive.

 

[Timothy Daniels]

When I first posted my question, I was unaware of the two
techniques: 'cloning' and 'mirroring'. Now I know. I think
mirroring is the way to go for my case, since I can store
multiple mirrors on the same backup drive.

"Image" is the term used for a copy of a partition that is stored
as a FILE on a medium that does not have to be a HD and which
may be compressed. An "image" must be "restored" to its original
form by reversing any compression and by copying it back to a
HD partition before it can be used..

"Clone" is a byte-for-byte copy that is stored on another
HD that may also contain a copy of the boot sector of the
partition and a copy of the Master Boot Record. A "clone"
can thus be directly bootable without any intermediate step.
Many clones may reside on a large capacity HD and any one
of them may be selected by the boot manager and immediately
booted after just a restart. In my system, I have a HD on a
removable tray that contains from 3 to 5 clones of my main
OS.

"Mirror" is an exact copy of a HD that is maintained in
REAL TIME and which contains all the data AND ERRORS
which exist on the main HD. It is usually used to provide
immediate (perhaps automatic) and transparent changeover
from the main HD in case the main HD fails. "Mirroring" is
not considered an archiving technique since it will be just as
corrupt as the main medium.

*TimDaniels*

 

[Timothy Daniels]

Only partly true. The OP can create an image file of the source
partition, the restore this image to the destination partition. It would,
of course, be nicer if the OP did not have to take this detour . . .

Yes, if you're have the extra time to do a "restore" to a new
HD in case the main HD fails, or to do a "restore" to your OS's
partition in case of file corruption, Acronis's True Image will
do that. If you're doing something like day trading with just one
PC, though, you'd probably want to use cloning rather than imaging
for quick recovery in case of HD failure or suspected file corruption.

*TimDaniels*

 

[Talal Itani]

"Image" is the term used for a copy of a partition that is stored
as a FILE on a medium that does not have to be a HD and which
may be compressed. An "image" must be "restored" to its original
form by reversing any compression and by copying it back to a
HD partition before it can be used..

"Clone" is a byte-for-byte copy that is stored on another
HD that may also contain a copy of the boot sector of the
partition and a copy of the Master Boot Record. A "clone"
can thus be directly bootable without any intermediate step.
Many clones may reside on a large capacity HD and any one
of them may be selected by the boot manager and immediately
booted after just a restart. In my system, I have a HD on a
removable tray that contains from 3 to 5 clones of my main
OS.

"Mirror" is an exact copy of a HD that is maintained in
REAL TIME and which contains all the data AND ERRORS
which exist on the main HD. It is usually used to provide
immediate (perhaps automatic) and transparent changeover
from the main HD in case the main HD fails. "Mirroring" is
not considered an archiving technique since it will be just as
corrupt as the main medium.

*TimDaniels*

But what about cloning? Cloning is also as corrupt as the main medium,
right?

 

[Talal Itani]

Yes, if you're have the extra time to do a "restore" to a new
HD in case the main HD fails, or to do a "restore" to your OS's
partition in case of file corruption, Acronis's True Image will
do that. If you're doing something like day trading with just one
PC, though, you'd probably want to use cloning rather than imaging
for quick recovery in case of HD failure or suspected file corruption.

*TimDaniels*

ok, now I understand it very well, thanks.

 

[Timothy Daniels]

Cloning is also as corrupt as the main medium,
right?

The clone you make now is as corrupt as the
main medium is now. But the clone you made
yesterday or last week may not be. The point
is that by the time you realize a file corruption
problem in the mirroring situation, the mirror will
have the same problem. Mirrors are good only
for fallbacks in the case of physical failures, not
data failures. For instance, RAID Level 1 uses
mirroring, wherein:

"100% redundancy of data means no rebuild is
necessary in case of a disk failure, just a copy to
the replacement disk" - from:
http://www.acnc.com/04_01_01.html

But the data on the mirror (perhaps containing the
results of just-completed sales transactions) is no
better than the data that is on the failed disk. The
"up-to-the-minuteness" is both the advantage and
the disadvantage of mirroring.

*TimDaniels*

 

[Shenan Stanley]

But what about cloning? Cloning is also as corrupt as the main
medium, right?

Only if you made a clone of the corrupt system.

Simple explanation:

RAID mirroring - this is when one hard drive (or more) replicate to another
hard drive (or more) in real time - would leave you with a corrupt system on
both hard disk drives if a software issue was to blame. Why? Because as
soon as the main system becomes corrupted - it has replicated to it's twin.

In non-computer terms... Let's say you were filling out a form and they put
a sheet of carbon paper under it and another form under that. You are
essentially filling out two forms at one time then... So any mistake you
make on the top form will be immediately replicated to the form under the
carbon paper.

To do RAID mirroring effectively you need proper hardware. It also will
ONLY save you from hardware corruption - and then - not every time. In my
opinion - this should only be used if all you are afraid of is hardware
failure - and even then - I just don't see it working well. I would use
another method to backup my data/system.


Imaging - or making a full copy, to a file, of a partition or drive using
imaging software (such as Ghost/TrueImage, BootItNG, etc) - will be a
point-in-time backup. If the image you took (file you made) of the system
was before any corruption - then you can restore said image and have a
working system again - making sure not to repeat the same mistake.

In non-computer terms... You are taking a picture with a camera of a glass
of pure ice water as the ice melts (one per minute)... Each picture you
take is slightly different because more of the ice has melted than the time
before. Whatever happens to the ice water - you capture. So if someone
dropped a clump of dirt into it while you were taking your periodic
pictures - all pictures after the clump of dirt shows the now tainted
drinking water. However - you can go back to the picture you took right
before the clump of dirt was dropped and you will have a picture of a
clean/pure glass of ice water.

To do imaging effectively - you need someplace to store multiple images.
Since it is a full system image, you may not need more than one - but you
may want to keep several. This means having some storage space several
times larger than how much space you take up on your current system. In
that way you can store a few exact images of your working system in case you
'automate' this and overwrite one good image with a bad one. I think, done
correctly and supplemented with periodic 'important' file backups - this
method is one of the best. There is an initial cost involved for the
softwware and necessary hardware - but i think it provides the best coverage
when planned and executed properly.


Cloning - making a full copy, to another drive/parition, of a partition or
drive using imaging software (such as Ghost/TrueImage, BootItNG, etc) is
also a point in time backup. You have to initialte the replication. If the
clone you make was before there was any corruption, then the clone drive
should work just fine. If you clone AFTER there is corruption, then your
clone is likely corrupt as well. I only say likely because there is a
possibility (if it is a hardware issue) that your clone will work where the
original does not.

In non-computer terms, consider someopne gives you a full filing cabinet of
forms and documents and then gives you another filing cabinet of the same
(or larger) size - but empty. You could either move everything from the old
to the new filing cabinet - but they want to keep the old filing cabinet in
building A and the new one in building B. So you photocopy ALL documents
and forms and you place them into the new filing cabinet in the same exact
way they were in the old filing cabinet. You have 'cloned' the original
filing cabinet now.

To clone effectively - you need a drive that has at least as much space as
you are currently using on your current drive. It can be the same size
drive or larger. In my opinion - cloning is not a good backup method as it
is time consuming and to have more than one backup of your system - you have
to have more than one hard drive to clone to. Otherwise - it's not really
cloning. I recommend NOT cloning unless you are trying to replace a current
drive with a newer/larger drive for some reason.


Overall - I think a good automated imaging system combined with a decent
periodic 'important' file backup would give you the best recovery for yout
time/effort/money.

 

[Talal Itani]

The clone you make now is as corrupt as the
main medium is now. But the clone you made
yesterday or last week may not be. The point
is that by the time you realize a file corruption
problem in the mirroring situation, the mirror will
have the same problem. Mirrors are good only
for fallbacks in the case of physical failures, not
data failures. For instance, RAID Level 1 uses
mirroring, wherein:

"100% redundancy of data means no rebuild is
necessary in case of a disk failure, just a copy to
the replacement disk" - from:
http://www.acnc.com/04_01_01.html

But the data on the mirror (perhaps containing the
results of just-completed sales transactions) is no
better than the data that is on the failed disk. The
"up-to-the-minuteness" is both the advantage and
the disadvantage of mirroring.

*TimDaniels*

I agree, I understand, thanks.