Good disk cloner (linux or windows) that can do track-by-track copy

Hi Team,

  I have a dedicated TACACS appliance server (linux based) which I have to do a major version upgrade on.  Unfortunately, there is no way for me to reverse the change if it fails, so I want to create "cloned" images of these disks so I don't really have  to touch them.  I have identical model disks of this appliance and I want to clone the 2 x 250GB SATA disks to this new set, and upgrade those, so that if my upgrade fails, I can re-clone again.

  What utility (windows or linux) have you guys tried that can do track by track (or sector by sector) copy of disks and will play well with USB to SATA cables?   Ideally, I would like to avoid opening up some chassis of some PC and connect SATA disks there, just to do a clone.  I have these $40 USB to SATA gizmos that I use when I have to read the stack of SATA disks on my shelf.

Thanks and regards.
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first >>   I would like to avoid opening up some chassis of some PC and connect SATA disks there, just to do a clone.  <<   you can do it that way - but it will take at least 10x more time to clone, so i suggest OPENING the PC's, and connect the drive directly.
i have used Casper with good result :
but there are others, like Paragon :
pick what you like!

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Gary CaseRetiredCommented:
While it WILL take appreciably longer to do this via USB bridge devices, it certainly won't be "... 10x more time " :-)    If you're using USB3 it won't even take ANY more time ... and with USB2 it will take 3-4 times as long as a direct SATA connection.

Note that many imaging utilities do NOT provide for an actual sector-by-sector duplication of the disk when making a "copy"  ... virtually ALL modern imagers only copy sectors containing data.    Be sure what you're using allows a true sector-sector copy of the disk.    I'd use the excellent Image for DOS product [ ].   If you select "Copy", you can simply choose your source and destination drives; then on the options screen check the "Copy Unused Sectors"  option and UNCHECK all other options.   This will create a true sector-sector copy of the disk.

Another alternative that will produce much faster copies is to use a hardware disk duplicator ... e.g.
rleyba828Author Commented:
Thanks everyone...  I am downloading a trial of the image-for-dos software.   I'll report here with my findings.
Gary CaseRetiredCommented:
It's very simple -- just run the included MakeDisk utility to create a bootable CD;  then just boot the CD to make your copy.    It works with both internal and USB-connected drives, so you can make the copies to your external docks, as you noted you'd prefer to do.
well -it's your choice
Semper PhiSystems IntegratorCommented:
Acronis Drive Image is linux based and it does sector by sector images. works for both windows and linux systems. very reliable.
Fred MarshallPrincipalCommented:
I've had lots of positive experience with Acronis Drive Image - run from a live CD boot.
Thomas RushCommented:
How much data are you cloning?  The USB interface is designed so that it allows one undetected error for every 9TB or so -- and USB cables may be far worse than this.

The SATA interface and drives are better than 10^12 bits, and SAS better yet.  

The point is, you may copy things faster or easier by hooking up a drive via USB connection, but you won't be as certain that your copied data is good.
Gary CaseRetiredCommented:
"... but you won't be as certain that your copied data is good. " ==> ANY good copying utility has a validation option ... simply selecting that will ensure you always have good copies.
Thomas RushCommented:
> ANY good copying utility has a validation option ...

Sure, they do.  Do most people do a compare after the copy to make sure it's good?  
Would someone who wants to get the copy done as soon as possible be likely to use the verify flag?
Perhaps for those people who would not ordinarily verify, it's useful to point out that a copy over a USB bus is much more likely to lead to lead to undetected corruption (what's your spreadsheet look like when a key '+' becomes a '-'?) than a copy over a SATA or SAS bus.

This issue of undetected corruption or mis-copies is one that most people haven't woken up to.  It was a minor issue when disk sizes were an order of magnitude or two smaller than they are today; it will become more and more of an issue as disks continue to grow larger, and we work with larger and larger data sets.  We who give advice to others should be aware of the dangers ourselves, and make sure we help those who depend on us understand what it means to them.
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