Starting from OBRM 6.3, the customer can see the information about folder size stored in the cloud.

Sometimes, when the restore procedure completes successfully, the folder sizes displayed in the cloud and recovered to the local computer are different.

For example, folder size in the cloud is 19.25 GB, but the recovered one is 15.6 GB.

In some cases, this difference (displayed size is larger than the restored one) can be significant. It depends on how many and how big are the files in the folder and how often they are changed and backed up.

Folder size in OBRM for Windows and in Dashboard

OBRM for Windows

To see the folder size in OBRM for Windows, start OBRM, and then click View/Restore in the upper right corner.

You will get the list of your protected devices. Select a device and a folder you want to restore.

You can see that the total size of the backed up data is 40.46 MB

First, lets expand the folder.

We observe three different versions of the same PST file. Two of them are 30.77 MB, and one is 40.46 MB.

Let’s see how this size is displayed in the Dashboard.


To see the data volume saved in the cloud for a specific device, click the Device Management tab on the Home page.

You can see that total size of the backed up data is 30.8 MB.

So we can see two different sizes: 40.46 MB is the folder size in View\Restore in OBRM for Windows, and 30.8 MB—in the Dashboard.

How file size is calculated

When a new file is uploaded to the cloud for the first time, it is treated as a baseline file, and its size is a baseline size.

When the next version (with changes) of the file (New1) is uploaded, the difference (Delta) between the baseline file and the new file is calculated. So, the new file is shown as follows: New1 = Baseline1 + Delta1.

The next version of the file (New2) is calculated as follows: New2 = Baseline1 + Delta2, and so on.

When the DeltaX exceeds 50% of the Baseline1 file size, a new baseline file (Baseline2) is created: NewX = Baseline2, and so on.

How file or folder size is shown

OBRM shows the size of the file as a sum of the corresponding BaselineY and DeltaZ.

The size of the file version for a specific date and time is calculated as a sum of the baseline and delta sizes, actual to that specific date and time.

The size of the latest versions of files is equal to the sum of the latest baseline file size and the latest delta.

In our case, Baseline1 = 30.77 MB, and Delta2 = 9.69 MB.

The Dashboard (and OBRM main window) shows the size of the file (or used space if the only file was backed up) as the size of its largest baseline file without any deltas.

In our case, largest Baseline = Baseline1 = 30.77 MB (rounded to 30.8 MB).

When OBRM starts the recovery process for a folder, it processes the following:

  1. Calculates and summarizes the sizes of all baseline files and all deltas of all files in the folder (and its subfolders), and shows this sum on the top of the recovery status window.

  2. Finds the latest baseline files and the latest deltas of all files in the folder (and its subfolders), and then starts to recover the latest versions of the files (in the selected folder and its subfolders).

  3. Refreshes the total amount and the total size of the restored files in the upper part of the recovery process status window.

After the recovery finishes, the size of the recovered folder may be smaller than the size of the folder in the cloud because only the latest versions of files were recovered, but the folder size in the cloud is calculated as a total of all baselines file sizes and all deltas for all files under it.

Used space calculation for account in cloud

Previously, we have calculated the used space in the cloud for a file with versions as follows: MAX Baseline + MAX Delta. Now, we calculate only MAX Baseline.

For example, consider a PST file with many versions that has the following baseline sizes and deltas in the cloud:

Baseline1 = 10 GB
Delta11 = 2 GB
Delta12 = 4 GB
Baseline2 = 15 GB
Delta21 = 1 GB
Delta22 = 3 GB

From this chain of versions:

MAX Baseline = Baseline2 = 15 GB
MAX Delta = Delta12 = 4 GB

Used space in the cloud for a file:

  • Before: MAX Baseline + MAX Delta = 19 GB
  • After: MAX Baseline = 15 GB

When the latest version (corresponding to Delta22) is restored to the file system: 15 GB + 3 GB = 18 GB.

When the folder size is calculated in View\Recovery: Total size of all baseline files and deltas is 35 GB.


The size of the recovered folder may be smaller than its size calculated in View\Recovery, but it will contain the same number of files as in this folder in the cloud.

Moreover, the size of the data (as how its calculated for billing purposes) can be significantly less than the size of the same amount of data stored in our storages.