Forum Discussion

AnandhaKannan_D's avatar
AnandhaKannan_D
Level 4
3 years ago

How Overwrite option in restore works

Hi,

Just want to know how overwrite option in backup technologies works during the restore.

In my scenario I have restored the full backup (which has file named A, B, C, D) later I restored incremental backup with overwrite option enabled, on the same folder to where I restored the full backup. I know very well incremental backed up A, B, C as it was modified after the full backup. So incremental backup will definitely replace the A, B, C. Here I want to know whether D will get overwritten or not, though i restore incremental it also take full backup to restore first then followed by incremental, in this case D will get overwritten(though i have enabled overwrite option.) or will be skipped ? 

Windows Server 2016
  • davidmoline's avatar
    davidmoline
    3 years ago

    HI AnandhaKannan_D 

    Let's try one more time. The behaviour will depend on what backup sets are included in your restore session.

    If the backup sets used for the restore does not include the full backup and only the incrementals, then selecting the folder that contains the four files (A,B,C&D) will not restore file D (as that was only included in the full backup). In the GUI that is controlled by changing the start and end date/time when searching for files to recover. In fact if you change the time frame to exclude the full backup file D will not be available to select.

    When you initiate the restore from the GUI, what happens then is sequentially, starting from the oldest backup, the required file(s) from each backup to cover your selection will be restored. Each file selected will be restored once only (from all available backups covered by the session) from the latest backup available of that file (unless of course you specify a specific version when selecting the files).

    Cheers
    David

  • Azhar4's avatar
    Azhar4
    3 years ago

    for the first part..No is the answer

    for second part, by default, restore window select the latest Full backups and subsequent Incr backup images for the data  and present it you in the window. you can either go with this default selection and restore with overwrite option , it will restore all the latest version of data, starting from the full image.

  • davidmoline's avatar
    davidmoline
    Level 6
    3 years ago

    Hi AnandhaKannan_D 

    The file D will be skipped on the assumption it was not included in the incremental backup. If you are using the BAR GUI, you can slect the specific backup and see what files are available - that will confirm which files will be restored from a particular backup. 

    David

    • DPeaco's avatar
      DPeaco
      Moderator
      3 years ago

      If you are restoring from the FULL backup with the overwrite option selected, then every file you have selected in the restore will be written to the location you specified (original location is the default). D file will get skipped during the incremental part of the restore since D was not updated after the Full backup. You can choose exactly what you want to do but you must put in the effort to select exactly what you want, when you want and where to land it with each part of the data recovery process.

      In short, if the D file wasn't backed up on the incremental backup (after the full), then NetBackup will not try to restore D again since it wasn't part of the Incremental backup file list.

  • AnandhaKannan_D's avatar
    AnandhaKannan_D
    Level 4
    3 years ago

    Yes file D was not in the incremental but in full backup it was there and I had already restored the full backup before restoring incremental. Now when I select incremental to restore, it also restore full backup first followed by incremental. D file already exists and now If I start incremental (full+incr) restore with overwrite option enabled, (full backup as first part in the incremental restore) will it overwrite D file or not?

     

  • AnandhaKannan_D's avatar
    AnandhaKannan_D
    Level 4
    3 years ago

    Rephrasing....

    Full Backup ( A file, B file, C file, D file )
    Incremental Backup ( A file, B file, C file )

    First I restored Full backup in folder named Test (A file, B file, C file, D file)

    Now I have a requirement to restore incremental to have the latest updated files in test folder.

    I have started the Incremental(Full+Inc) restore with overwrite option enabled to the test folder.

    D file in the test folder will be overwritten or not?, though i have enabled overwrite option and in incremental restore first it try to restore full backup (which has D file) followed by incremental backup in the test folder.

    • Azhar4's avatar
      Azhar4
      Level 4
      3 years ago

      if you have already performed full restore , why are you selecting Full again with Incremental image?

      you just need to select the Incr image and restore . only abc will be there  per ur given info

    • davidmoline's avatar
      davidmoline
      Level 6
      3 years ago

      Hi AnandhaKannan_D 

      For step 2 since you are selecting the backup set that includes the full backup, all 4 files (A,B,C & D) will be restored and overwritten which includes D

      David

  • Michal_Mikulik1's avatar
    Michal_Mikulik1
    Moderator
    3 years ago

    Hello,

    Well, it looks like a quizz question rather than a practical problem..

    Agreed, the file D will be overwritten. But it has nothing to do with the previous D file origin, e.g. that it was previously restored from 1st full. It would be overwritten in any case, regardless of how the D file appeared in restore folder and what it contains.

    Regards

    Michal

  • AnandhaKannan_D's avatar
    AnandhaKannan_D
    Level 4
    3 years ago

    I need more clarity on Azhar4  reply. 

    Someone correct me If I am wrong. Even if we select incremental(4-Dec, incr) in the backup set it also perform the restore of full backup along with the other incremental in the chain. Right?

    In this case I had only 4 files so i can select any of the modified file individually from incremental to get the latest modified file which I require from the backup. But what in case if i have 10000 modified files in incremental and I want specifically 5000 in that. Selecting 5000 files is not possible practically. right. So i should go for the complete backup set with overwrite option enabled though I have already restored the full backup alone from the backup set.

    • davidmoline's avatar
      davidmoline
      Level 6
      3 years ago

      HI AnandhaKannan_D 

      Let's try one more time. The behaviour will depend on what backup sets are included in your restore session.

      If the backup sets used for the restore does not include the full backup and only the incrementals, then selecting the folder that contains the four files (A,B,C&D) will not restore file D (as that was only included in the full backup). In the GUI that is controlled by changing the start and end date/time when searching for files to recover. In fact if you change the time frame to exclude the full backup file D will not be available to select.

      When you initiate the restore from the GUI, what happens then is sequentially, starting from the oldest backup, the required file(s) from each backup to cover your selection will be restored. Each file selected will be restored once only (from all available backups covered by the session) from the latest backup available of that file (unless of course you specify a specific version when selecting the files).

      Cheers
      David

    • Azhar4's avatar
      Azhar4
      Level 4
      3 years ago

      for the first part..No is the answer

      for second part, by default, restore window select the latest Full backups and subsequent Incr backup images for the data  and present it you in the window. you can either go with this default selection and restore with overwrite option , it will restore all the latest version of data, starting from the full image.

  • Nicolai's avatar
    Nicolai
    Moderator
    3 years ago

    If D is selected in a backup and exist on disk AND overwrite is enabled - D will be overwritten.

    If D is selected in a backup and exist in disk AND overwrite is DISABLED - D will not be overwritten.

    The "devil detail" is the overwrite option.