How does the differential Backup take in virtual incremental backups?
I have created one base backup and 9 differential backups.
To recover the partition, I copied two files, the base file and the 9th file, from external disk to a partition in internal disk drive.
(It's not necessary but I did for some reason.)
I extend the 9th image file (9xx.tib) on Windows Explorer and I was surprised.
I could see all steps from 2nd to 9th backups and even opened a text file from the 3rd step.
But there wasn't 3rd differential backup file there.
In YouTube
"Incremental and Differential Backups. Background. Part2 "
http://www.youtube.com/watch?v=DvwJsUbuNC0
It says that the differential backup file size adds up to the all incremental backup files size.
If the differential backup file includes all incremental backup files, what I experienced wasn't so strange.
To recover the 7th image, I don't need the 7th file but I need only 9th file.
So if I have 9th differential backup I may delete from 2nd to 8th differential files.
But there is a question for creating the new differential backup.
If I had only base file and the last backup, I mean the other files are all deleted, I think the 10th differential backup cannot take in all virtual incremental history to the image.
When I'm going to create the 10th differential backup, which files are necessary to create 10th differential backup?
Does TrueImage need base backup and all differential, from 2nd to 9th all differential backups, to take all other virtual incremental backup into the 10th backup?
If I create the new backup, shouldn't I delete any other previous differential backups, from 2nd to 9th?
Thank you in advance,
Ken (Japan)
I'm not a native English speaker.
Version : Acronis True Image Home 2010
Hello, Fedor Larin!
I really appreciate your support.
It was very useful advice for me because it seems I can delete many needless differential files.
Before deleting the files, I would like to confirm one thing.
When I’ve deleted all differential backups and then I create a new differential backup as the task run number 9 with the base full backup, I can recover the partition from the base full backup and the task run number 9 differential backup.
In that case, for example, can I recover the partition which I created when the task run number was 5?
In other words, even in this case, may I think that the base full backup and the task run number 9 differential backup also include the complete partition images of any other younger task run numbers?
I saw all differential backups in only two files, the base full backup and the last task run number 9 differential backup, so I’m confused.
Thank you in advance,
Ken (Japan)
Version : Acronis True Image Home 2010
Ken,
Any specific differential backup represents your computer as it was at time the backup was created. It is the accumulation of all changes from full to date of differential.
A differential backup will include all changes made on your computer from the time of full until the time of the diff creation.
If you want to put your computer back to the same condition it was on a specific day, you will need to restore the differential backup for that specific date.
When doing a restore, while you only need the full or a full plus a single diff backup, you really need to keep each and every diff if you want the capability to restore your compuer to what is was on a specific date.
If you were to validate your backup uisng only the full plus the last one with all the others deleted, the validation has always failed in the past but still capable of being successfully restored.
A little more info here.
http://forum.acronis.com/forum/38799#comment-122496
> In that case, for example, can I recover the partition which I created when the task run number was 5?
No. The differential backup created at some point of time carries only the disk state at that point. The content of 'backup explorer' - i.e. what you see by doubleclicking the .tib files - is misleading in this case, as it shows items corresponding to deleted differential backups.
Hello, GroverH,
Thank you for your help.
I could put my thoughts clearly in order by your detailed explanation.
Hello, Fedor Larin.
> The content of 'backup explorer' - i.e. what you see by doubleclicking the .tib files - is misleading in this case, as it shows items corresponding to deleted differential backups.
By your information, I think that
In my case, the older task run number differential backup just had a kind of file index of younger task run number differential backups, but there isn't substantial files there.
The reason I could recover a file from the younger task run number in older task differential file set was just the same file existed when I run each task run number.
I understood clearly.
I couldn't solve the problem without your help.
I really appreciate it.
Ken (Japan)
Version : Acronis True Image Home 2010