Why are my incremental backup files so large?

Hello,

Welcome to our community!

I advise you to review the following documentation:

• https://kb.acronis.com/content/60104
• https://www.acronis.com/en-us/support/documentation/ATI2024/#13778.html?Highlight=sector

Do you have the sector-by-sector option enabled? The sector-by-sector mode copies all hard disk sectors, and not only those that contain data.

Please note that, in order to have a smaller size in the backups, you should select the option: Single version scheme - https://www.acronis.com/en-us/support/documentation/ATI2024/#16515.html

Also note the incremental backups are merged in the full backup once the retention rules are applied.

I suggest you raise a ticket with our support so this can be investigated. We need to see all the parameters and check if this is expected or if there is some issue: https://kb.acronis.com/content/8153

Best regards.

Hunter, the incremental backups are each merged into the same file as the full backup so you will not see separate files created for each increment.

Also, it is recommended that instead of specifying days in your cleanup rules, you could specify number of chains. The days method can get confusing. In your case, you want 30 increments so you could say to keep no more than either 2 or 3 chains. Since a chain spans a month, you might want to keep three which would cover from 2 to 3 months back.

Jose Pedro Magalhaes wrote:

Hello,

Welcome to our community!

I advise you to review the following documentation:

• https://kb.acronis.com/content/60104
• https://www.acronis.com/en-us/support/documentation/ATI2024/#13778.html?Highlight=sector

Do you have the sector-by-sector option enabled? The sector-by-sector mode copies all hard disk sectors, and not only those that contain data.

Please note that, in order to have a smaller size in the backups, you should select the option: Single version scheme - https://www.acronis.com/en-us/support/documentation/ATI2024/#16515.html

Also note the incremental backups are merged in the full backup once the retention rules are applied.

I suggest you raise a ticket with our support so this can be investigated. We need to see all the parameters and check if this is expected or if there is some issue: https://kb.acronis.com/content/8153

Best regards.

 

Thank you for your reply.

1. sector-by-sector mode is NOT selected

2. Single version is selected.  This is a custom scheme

The answer was provided by  BrunoC below.

BrunoC wrote:

Hunter, the incremental backups are each merged into the same file as the full backup so you will not see separate files created for each increment.

Also, it is recommended that instead of specifying days in your cleanup rules, you could specify number of chains. The days method can get confusing. In your case, you want 30 increments so you could say to keep no more than either 2 or 3 chains. Since a chain spans a month, you might want to keep three which would cover from 2 to 3 months back.

BrunoC

Thank you.  I think this is the answer.  I verified that all files are actually contained in the single merged backup file by using the Windows Explorer integration to examine the backup file (this is a very cool feature I have not seen before).

My only confusion is that this does not match the picture and description of the Incremental Method shown here:

 https://www.acronis.com/en-us/support/documentation/ATI2024/#13711.html

This shows that you would have a new file 1, 2, 3.. for each backup and that each file would contain the incremental data.  Since I only have 1 file for each backup, this cannot be true.  Perhaps the documentation is out of date?

Also, I will change the scheme to keep no more than 2 full backups.

Thanks again.

My only confusion is that this does not match the picture and description of the Incremental Method shown here:

 https://www.acronis.com/en-us/support/documentation/ATI2024/#13711.html

This shows that you would have a new file 1, 2, 3.. for each backup and that each file would contain the incremental data.  Since I only have 1 file for each backup, this cannot be true.  Perhaps the documentation is out of date?

The documentation is wrong!  See KB 63516: Acronis True Image 2020: Incremental backups do not create separate files when using new backup format which correctly describes how things work for .TIBX files.

The following may be helpful for understanding how automatic cleanup works too.

Automatic cleanup

There can be lots of confusion around the topic of automatic cleanup which can be better understood if some basic concepts are known!

First:  automatic cleanup only works on complete(d) versions / version chains.  Do not expect individual elements of version chains to be cleaned up, such as incremental or differential files!

Second: automatic cleanup only runs after a new Full backup for the next version / version chain has been created successfully.  This means that there must be sufficient free space available on the storage drive / location to hold a new Full backup image file!

Third: counting of days does not start until after a new Full backup file has been created when using the option to ‘Delete versions / version chains older than X days.’  It does not start for the active backup version / version chain before that point!

Fourth: the simplest & easiest automatic cleanup option to use & understand is to ‘Store no more than X recent versions / version chains.’  The criteria here means that if you set X = 2, then when the X+1 (3rd) version / version chain is created successfully with a new Full backup file, then the oldest version / version chain will be deleted by automatic cleanup.

Example:

Incremental backup task, using Full plus 5 Incremental backups before next new Full backup.

Task scheduled to run daily with automatic cleanup set to ‘Store no more than 2 version chains.’

Day 1 – Full backup created.

Days 2 – 6 Incremental backups created.

Day 7 – Next new Full backup created. 

Days 8 – 12 Incremental backups created.

Day 13 – Next new Full backup created.  Automatic cleanup deletes files created on days 1 – 6.

If the same task used ‘Delete version chains older than 7 days’, then those 7 days wouldn’t start counting until day 7 for the first set of files (version chain 1) and not until day 13 for the second set etc.  So automatic cleanup wouldn’t delete the oldest chain until day 14 in the above example.