Backup Size Continuously Growing
Good Day,
I am having an issue with Acronis Backup 12 where the backup size on my Acronis Management Server is continuously growing by 6.5GB on every backup even after the backup retention policy is being applied. I have contacted Acronis Technical Support, and they have answered; however, I am not satisfied with the answer. In order to fully explain in the easiest possible manner, I am just going to copy the email correspondenace between myself the the Acrnois Technical Rep (only the relevant parts to this question). Hope someone here can help.
--Beginning of Email Correspondence--
Myself: Scenario: I setup two different servers to run a full backup (Entire Machine). The backup scheme was “Always Incremental (Single File)” which was the only scheme I could select by the way. The cleanup was set to delete after 2 backups. One server was the Acronis Management Server, the other a file server.
The backups on the Acronis Management server increased by about 6.5GB every time even though no new data was added to the server. What is causing this increase in size? Once again, even though only 2 backups were saved, the backup file increased by about 6.5GB every time. I would imagine the size should remain the same after the 2nd backup as only 2 backups were being saved.
Acronis Rep: When we perform backup of disk, the backups are taken in block-level. Each data block will have its own hash value (signature). So any machine which contains databases while being backed up, the data is constantly being changed at block-level. Hence the backup size differs from other machines which do not have databases.
Myself:
I'm still not satisfied with the answer to my question. If I understand correctly, because of how databases work, any change to a database would change the hash value for each data block the database is located on. I’m okay with that reasoning ; however, that should mean that the new data being backed up should be the entire database, and as a result, the backup size increase should be the size of the database. Is this correct? If so, is the Acronis Backup Manager database 6.5GB’s in size? I was not able to locate any Acronis data that large (perhaps I am looking in the wrong place). Furthermore, even if the database was 6.5GB in size, the backup archive should not increase by this size after the backup plan’s retention period has been reached. Please see excerpt from the link you provided to me.
When a certain backup expires due to the pre-defined retention rules, the backup algorithm just marks these outdated backup blocks as “free” ones. The blocks of expired backups with dependencies (which are needed to restore the newer backups) are not marked as “free” to ensure the archive consistency. The always incremental archive total size includes the size of the “used” blocks and the size of the “free” blocks: the initial archive still occupies the same space on the storage as before, however all newer backups will be written to the “free” blocks first, and only if all the “free” blocks are filled, the total size of the archive will be increased.
Therefore, if the database really is 6.5GB’s (which I don’t think it is), then after the retention period has been met, 6.5GB’s of space should be marked as “free space” in the archive. The next time a backup is run, the backup of the database should simply fill in the free space as the database size is relatively the same size.
Can you please explain to me why this is not happening, or correct me if I am misunderstanding something
--End of Email Correspondence--
So this is where I am currently at with the tech support rep. I wanted to also post the question here to the forums because I figured it's always good to ask around. I hope someone here can help me with the issue I am experiecing or explain what is happening.
Thanks,
Ryan.

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Good Day Vasily,
I've attached the pictures. Can you please explain to me how to generate the report you requested? I was able to collect some system information called sysinfo.zip but it was too big to upload. If this is what you require, I will find another way to get it to you. When you look at the pictures, you will notice that the backup TIB file increases by about 6.25GB on average after every backup (The size increase actually increases a little bit with every backup). If you look at the backup plan, you will see that the retention period is 2 backups. There has been NO new data added to the server between these backups. Therefore, I would have expected that the TIB file size would remain about the same size after the third backup. This is because as the rentention period is met, the database file should be marked as "free space" in the TIB file, and the new backup should occupy the free space. Also, I'm still not sure if this is really the result of backing up the Acronis management database as I think 6.5GB is too large.
Please note that this is a test environment. We are testing on this server before implementing in our production enviornment. I can make any changes that you recommend or request.
Thanks,
Ryan
Attachment | Size |
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400848-135748.zip | 590.68 KB |
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Hi Ryan,
There is definitely something wrong in your case - the sizes are unexpectedly large. With your settings the backup size should increase incrementally until 3rd backup (when retention rules come in play) and after that change insignificanly. I've also tried reproducing the issue in our QA lab, but was unable to - in my case all backups were incremental and added less than 1% to the total backup size. Therefore the problem in your case should be investigated through the log files.
Since you've captured system report already and it's too big to be attached, you can extract only \ServiceProcess\ folder from it and re-pack it into .zip. This folder contains logs from the actual backup process - history of executed backups. If you can send it to me for analysis - that would help.
TIP: this folder can also be found on the backed up machine (if you backed it up via Agent for Windows installed inside) under c:\ProgramData\Acronis\ServiceProcess\ path - you can get it right from there.
Thank you.
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Hi,
Is it possible that one of the servers you are backing up is also used to store the backups for both servers? What I mean is are you sure you are not backing up the backup location in one of your plans by mistake?
If yes I would suggest to not include the disk/partition where the backups are stored in the backup plan as it may be the cause of the unexpected size growth.
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Good point - indeed in this scenario the size would grow exponentially :)
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Hi TP,
This was exactly the problem!! The backup drive was located on the Acronis Management Server as Drive E:\ and the "Entire Machine" was selected as "what to backup". This resulted in the server backing up the backup as you stated. I did not think about this, as Windows Server Backup does not allow you to do this. When you select a drive to backup that is the storage area for your backup, it automatically removes it from the backup job. I thought that Acronis would have had the same logic as well. I resolved the issue by adding drive E:\ in the file filters exclusion list.
Thanks TP and Vasily for helping me resolve this issue! Really appreciate it.
Regards,
Ryan
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