Incremental backup questions

Discussion in 'Acronis True Image Product Line' started by Arthurj123, Aug 28, 2007.

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  1. Arthurj123

    Arthurj123 Registered Member

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    I'm thinking of switching to ATI for my backups, and I'd like to know a few things about how incremental backups work in ATI. I hope you folks can enlighten me.

    Until now I've been using XXClone to make weekly backups of my entire system disk to a partition on a larger external drive, rotating weekly between two alternating backup partitions. Initially I did a full drive backup, but after the first full backup I have been able to stick with quicker incremental backups. XXClone Pro will do an incremental backup that changes only the modified/added/deleted files to make the backup copy the same as the source copy.

    I've had good success with XXClone, and in the past I have successfully cloned or restored WinXP systems from one drive to another. Recently though I had a problem with when I cloned my system to a larger hard drive - it broke the Microsoft Installer patch database somehow. I used Seagate DiskWizard instead to do the clone, and that worked correctly. So of course now I'm thinking of switching to ATI for my regular backups.

    Will ATI do incremental backups the way that XXClone did? That is, I have an existing backup partition that contains a complete copy of my system disk, and I want to update it with just the changes.

    Will ATI let me make multiple incremental backup sets on top of an initial full backup? That is, I make a full backup at the start of the month, and then create a weekly incremental backup set with just the changes from the last backup.
     
  2. seekforever

    seekforever Registered Member

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    I'm not sure if TI will do exactly what you ask in your first question - update the backup copy of your system disk.

    Incrementals in TI.
    Since you are dealing with bootable volumes you will want to make an image rather than doing a Files and Folders backup.

    A Full image of the partion, partitions or whole disk (as you wish) must be made first.

    The first incremental then creates an incremental image containing the changes made since the Full image.

    The second incremental then makes another incremental image which contains the changes made since the previous incremental was created.

    The third and subsequent follow this pattern.


    TI will also make differential images as well. Each differential captures all the changes made since the Full image. This allows you to restore to the latest backup by restoring only the Full and the last differential. Since they contain all the changes since the Full they tend to be larger than incrementals.
     
  3. Arthurj123

    Arthurj123 Registered Member

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    So it sounds like ATI will do one of the things I want, i.e., complete image backup followed by incremental (or differential) backups for a while.

    However it won't do the other thing that XXClone would, i.e., an incremental update of the full image backup to make it current without taking as long as making a new full image backup. Correct?
     
  4. seekforever

    seekforever Registered Member

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    I'm not sure of what you mean by "make it current". Are you referring to merging the incremental with the full to make one up-to-date full archive file? TI never modifies an existing backup file.

    If you have a Full and then make an incremental, the incremental typically takes a much shorter time since it is only capturing the changes made since the full (or the last incremental if it exists). The Full plus the incremental(s) constitute a current backup which can be restored if necessary.
     
  5. Arthurj123

    Arthurj123 Registered Member

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    Precisely. The backup model with XXClone is that you are making one single image backup copy of your drive and keeping it current by means of regular incremental backups. That way if your drive suffers a failure, you just unplug it, plug in the backup drive in its place, and you are up and running without doing any further incremental restoring. The disadvantage is that you aren't keeping any history, unless you maintain multiple separate backup drives or partitions.

    It occurs to me to wonder then if the ATI incremental and differential backups include the effect of file deletions. In other words, if I restore a full image backup made by ATI, then an incremental or differential backup on top of that, do I end up at the same final state as my current drive when last backed up? Or do the incremental/differential restores only add and change files without deleting any?
     
    Last edited: Aug 28, 2007
  6. seekforever

    seekforever Registered Member

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    File deletions are included in the diff/incrementals.
     
  7. Arthurj123

    Arthurj123 Registered Member

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    Ok, thanks for the information.

    Then I should be able to use a new backup procedure with ATI of making one full image backup and adding daily or weekly differential backups until they get too big. It would only take a 2-step restore to recover to the checkpoint of any individual backup.
     
  8. seekforever

    seekforever Registered Member

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    TI will do it all in one step. Just select the differential or incremental of interest and TI will restore the Full as well as the required diff/incrementals.

    A couple of tips:
    Even though you only need the full and the differential to do a restore, TI will not validate the archive unless all of the intermediate differentials that were created are present. Acronis is aware of this flaw and hopefully will correct it.

    If you have a bad incremental in a chain, any incrementals later than the bad one are also useless. This suggests you don't make one full and then a long chain of incrementals rather than making another full one within a reasonable period.

    If you validate after doing an incremental, TI validates the full plus all of the incrementals already made - not just the last one.

    Don't delete all of your old backups. It is never a good idea to have only one backup just in case something goes wrong with it.

    When you first use TI create and run the recovery CD. Make sure you can validate an archive made either by it or by Windows. The recovery CD is Linux and you must ensure this environment runs on your PC since it is what you need to run to recover from a dead HD. Creating the archives in Windows and valiating in Windows is not good enough since different drivers are used.

    Experienced users on this board will tell you that to know if your backup strategy is working, it requires testing the recovery. Restoring an archive of your system to a spare HD is the best test by far.
     
  9. Arthurj123

    Arthurj123 Registered Member

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    Intermediate differentials? Surely there's no such thing? (or shouldn't be, anyway). Each differential backup should be independent of any others, requiring only the baseline full backup.
     
  10. thomasjk

    thomasjk Registered Member

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    Seekforever was referring to validating the archive. In order to do this you must have all the differentials created. A bug that has been discussed here many times.
     
  11. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello Arthurj123,

    Thank you for your interest in Acronis Disk Backup Software.

    Please be aware that there are two approaches available:

    Clone Disk - migrates/copies the entire contents of one disk drive to another;

    Backup - creates a special archive file for backup and disaster recovery purposes;

    Please take a look at this FAQ article explaining the difference between Clone Disk and Backup approaches in more detail.

    Actually, Clone Disk approach is usually used to upgrade the hard drive (e.g. install a larger disk), while Backup approach is basically dedicated for the complete data backup and disaster recovery purposes. Since you are interested in backing up your hard drive for the disaster recovery purposes, I would recommend you to follow Backup approach.

    Moreover, there are several advantages of creating an image over the disk cloning procedure such as: you can create an image without rebooting your PC, image creation can be scheduled for the particular point in time, Acronis True Image allows you to create incremental and differential images, image archive contains only the actual data and so it has a smaller size, images are ordinary files and so they can be stored on any type of the supported media, etc. However, the final choice is always up to your needs.

    Please also notice that you only need one restore procedure to restore to the state of the chosen incremental/differential. You don't need to restore the original full image, and then gradually restore incremental ones; instead, you'll get a list of possible states to restore to.

    You can find more information on how to use Acronis True Image 10.0 in the respective User's Guide.

    Thank you.
    --
    Marat Setdikov
     
  12. Arthurj123

    Arthurj123 Registered Member

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    Thanks, I understand the differences and advantages of backup vs. clone. ATI seems like a good product, although it would still be nice if Acronis added the one good feature of XXClone which is still missing from ATI: the ability to do incremental updates of a cloned drive.

    The advantage of having a cloned drive over a backup data set is that it's ready to plug and go at any time, no need for the additional step of restoring a backup, which might always fail or have some problem. The further advantage of being able to do incremental updates of the cloned drive is that you can very quickly and easily keep it up to date without having to do a full copy - increasingly important with increasingly bigger drives.

    I like being able to plug my backup drive into any system and read the files from it, or boot from it if necessary. I'm always a little bit leery of proprietary one-product backup data formats that might turn out to be a bit too fragile the one time you really need it.
     
  13. Xpilot

    Xpilot Registered Member

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    Hi Arthurj123,

    You might like to consider my method of working with TI. Full image backups run from a schedule so there is a stock of automatically managed main HDD images stored on an internal secondary drive.
    At my chosen interval (usually daily) I pull the main drive that has just been imaged and put it to one side. This drive then becomes an ultimate ready to go HDD. The next step is to insert a previous main drive and bring it up to date by restoring the latest image. Then carry on working as normal.

    As all imaging and restore procedures are done internal to internal drive both imaging and restores are far quicker compared to using external drives. Restores are faster than clones and are about 4~6 time quicker than from the standard TI rescue CD.
    Apart from raw speed there is no need to run validations which is another time saver. There is never any doubt as to the validity of the backup drive because it was the one that was working a few minutes ago! I actually use three main drives in the mix for extra redundancy.

    To make the operation smooth and sweet the main drives are held in removable drawers and their rack is in a spare 5.25 bay in the front of the PC tower. Change over time is how long it takes to shutdown and reboot to the refreshed drive plus the few seconds to do the actual swap.

    Xpilot
     
  14. Arthurj123

    Arthurj123 Registered Member

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    It's nice to have a guaranteed working ready-to-go drive as your backup, but I see two problems with your procedure, Xpilot:

    1. You still have to take the time to do full drive imaging for each updated backup with this method. With my old method of rotating backups using XXClone, I always had two backup drives (most recent and 2nd most recent) ready to go, and each incremental update only took a few minutes.

    2. Your method works well if you have swappable drives, but like most people I'm using an external drive for backup.
     
  15. Xpilot

    Xpilot Registered Member

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    1.The computer takes the time to do the backup imaging not me. It is scheduled to happen when it would otherwise be idle eg. lunchtime.

    2 I was using external drives but I found them slow and cumbersome compared with internal drives. I cannablised one of them so the drive is now in one of the swap drawers. My other remaining USB drive has found other uses.

    3. Does one external drive give sufficient protection against all likely failure modes ? I used to use two myself.

    Xpilot
     
  16. seekforever

    seekforever Registered Member

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    No, and I know you know this :) , it certainly doesn't. I can easily recall a couple of posts describing how their externals were rendered useless by some catastrophe.


    I have posted at various times saying I consider Xpilots method to be a very good one and putting the backup into immediate service is probably the best way of ensuring you have made a good backup. However, I doubt if it is perfect since you could have some obscure file that is corrupted and never notice until you need it.

    On a more philosophical note, I think you have to approach your backup strategy like you approach everything else in the computer world. Namely, what is it that you are trying to achieve and what are the real requirements.

    I personally couldn't give a rat's butt if it took 30 minutes or more to restore a machine because of a HD failure. First, they are very rare and secondly I don't do anything like a business or super-important that requires very high computer up-time. I also have more than one computer.
     
  17. Xpilot

    Xpilot Registered Member

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    Well if an obscure file were corrupted I have a series of ten previous backups to search for a pristine version.
    However I think it is an unlikely event to ever occur because TI's normal controls would pick this up.
    I know very little of TI's inner workings but I believe that check sums are generated as part of the imaging process and they are again checked when a restore is carried out.
    I base this on the fact that, very rarely, a restore will actually fail. The reason given is that the archive is corrupt. Sure enough if I then run a validation, a thing I never normally do, the archive is confirmed as corrupt. I presume that this failure is due to a discrepancy in one of the check sums.
    As you appreciate a failed restore under my way of working is really a non-event and is soon corrected .

    Xpilot
     
  18. Arthurj123

    Arthurj123 Registered Member

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    As I understand it, ATI's full backups, incremental backups, and differential backups are all sector-based rather than file-based. There is a separate file-based backup capability, but it's a later add-on not connected to the basic sector-based backup functionality.

    Advantage: faster full backups
    Disadvantage: bigger incremental/differential backups
     
  19. fredthejerk

    fredthejerk Registered Member

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    TI 10 latest build

    a few things about so called incremental/differential backups. Firstly the system sometimes overrides any choice & u end up with a full backup so it seems? This is normal I think. However unlike, say Ghost 10, which is honest about this & gives a new name to the file, TrueImage doesn't ( cannot?) ; what is presented as an incremental/differential backup is really a complete one & has the same size as the original ( more or less) This is something I dont like as it leaves doubt whether u can delete the earlier states?
     
  20. Arthurj123

    Arthurj123 Registered Member

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    No, that's no so.
    When I tested this, my original full backup file was 32 Gbytes, the first differential backup a day later was 1.5 Gbytes, and the second differential backup a week later was 2.2 Gbytes. Looks like there's a high overhead initially on differential backups compared to the number of files that actually changed, but it's still very worthwhile.
     
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