Back-up and logboook sizes in Urbackup are really confusing me.
I hope someone is able to clarify some numbers for me.
The example log below is created incremental over Internet with a Windows ChangeBlockClient onto server BTRFS filesystem. I know BTRFS has some nice tricks like compression e.a. But then still the backup size numbers in Urbackup don’t seem to add up.
Settings:
Compressed Internet/active transfer: ON
Internet/active incremental file backup transfer mode: Block-differences Hashed
Logfile:
12-04-24 09:23
INFO
Transferred 169.383 MB - Average speed: 15.7954 MBit/s
12-04-24 09:23
INFO
(Before compression: 377.639 MB ratio: 2.2295)
12-04-24 09:23
INFO
37.8569 MB of files were already present on the server and did not need to be transferred
In Activities view and Backups:
Used Storage: 25.16 GB
So how do we get from Before compression: 377.639 MB to used storage 25.16 GB ?
And It gets even more confusing for me when you realise I live in NLD, we use the “,” and “.” different then in the US for example. We use the POINT here for thousand numbering.
Can someone please help me get answers to the following questions?
Q 1: Is in Urbackup 377.639 MB almost 378 MB, or is it 377 thousand MB?
Q 2: How much data did this incremental in MB or GB add to the server HD?
Q3: If 377.639 MB is sent and 37.8569 MB was already present; How do we get to a used storage 25.16 GB ?
Q4: The numbers 377.639 MB sent and 37.8569 MB already present suggest there is 10 times more data sent then already present?! This is impossibly if you realise this was an incremental where most data was already here. So is the . placement in one of these numbers an error?
So many different numbers, and so confusing. I would appreciate it very much if someone could clear things up a bit.
ps. I’ve read the complete manual, and many forum topics. But I was not able to find a correct answer for my questions. Sorry if this is answered already and i missed it.
Dear John,
The key to understanding your questions is BTRFS.
you cannot use typical Linux size reporting tools to get an answer.
BTRFS has it’s own commands for reporting space used.
You see BTRFS doesn’t just do compression (if you turned it on).
It does a sort of deduplication.
So that;
Assume I have a folder on my server that contains files A,B and C.
My client has modified A and created a new D in its folder that is going to be backed up.
So, the client only needs to send A and D.
The server will SHOW a new copy of the folder containing A,B,C,D
BUT the space occupied by the whole filesystem has changed very little because BTRFS has used “sub volumes”.
Pointers flying off in all directions to save space.
Plus, if you use “bees” or similar utilities, parts of files can be deduplicated by pointing them to an identical chunk SOMEWHERE within the whole filesystem.
Hence, the urbackup admin web page stats can show you have used 2.5Tb for your windows machine and yet the actual space used in the BTRFS filesystem is only 800gb. (I speak from experience).
I knew about btrfs and that it cant be calculated the “standard” way.
But why does Urbackup display info when it’s known to be incorrect? Better dont display at all, then display wrong info…
I have much knowledge about computers, but very little about btrfs.
I 'm going to read more about btrfs usage in the near future. But for now i allmost can’t believe there is no commmand to calculate real used/available disk and folder space on btrfs systems?
If there are btrfs commands available to correctly calculate folder sizes, i believe Urbackup should use that on btrfs systems.
If they dont exist i might as well put a stick in my nas to measure the hdd fill level
Personally I like to know how much my data “would cost” - via the Urbackup stats. I can easily view the used versus free in OpenMediaVault’s filesystem display or by ssh’ing to my backup server and using btrfs commands.
HOWEVER, It would be even more useful if the Urbackup stats ALSO showed “space consumed” as well.
