Missing HD Storage

[TorKnutzen]

Hi,

First of all, I have only very basic knowledge of NAS setups, so I'm assuming below problem is entirely linked to me not understanding how to properly configure my NAS.
I have a Synology DS718+ 24TB 2 Bay with 2 x 12TB Seagate IrownWolf . I didn't really configure anything, just used it like it came delivered (via Amazon).

Somehow I don't understand how the storage works.
So, these are 12TB disk in Raid1 setup, so I get 12 TB storage, and via Storage Manager I learned that this is actually 10.91TB, and with the Btrfs file system the total capacity comes down to 10.47TB.
Screenshot (I don't know what Multiple volume means. I did not enable this. I myself did also not define this 'Storage Pool 1' setup) :

Fine. All good I guess.

Now, the system tells me that I'm using 10.15TB, meaning storage is running low. Not so good.

However, when I made a report with Storage Analyzer, the total capacity of all files adds up to only 8.15TB (as you can see in below screenshot).
So, I'm missing 2TB somewhere...

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Extra info:
The different shared folders are mapped as network drives in my Windows10 pc and I copy paste and delete files just like 'normal' Windows folders.
Today I deteled the '#recycle' subfolder which contained a high volume of large files, via Windows. This was at least 1TB but it did not give extra 1TB free capacity...
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What am I missing here? Where is the 2TB missing capacity? Why has emptying the recycle bin no impact on freeing up capacity?

Thank you in advance for your help and advice.

 

[Lewis]

Not sure did i understood your issue correctly (apology if I didn't) but in case you didn't know HDD manufacturers are "stealing" GBs since they count 1kb is 1000 bytes instead 1024 so on larger HDD drives after formatting the drive you lose real disk space.
So as the drive is larger in TB the more space you will "miss" if you count them as 12+12=24 but in reality it's 21.8x.

 

[TorKnutzen]

Not sure did i understood your issue correctly (apology if I didn't) but in case you didn't know HDD manufacturers are "stealing" GBs since they count 1kb is 1000 bytes instead 1024 so on larger HDD drives after formatting the drive you lose real disk space.
So as the drive is larger in TB the more space you will "miss" if you count them as 12+12=24 but in reality it's 21.8x.

thank you for your time to reply.
Apologies that I was not able to explain my question better, but yes I know about the difference between the 12TB of the manufacturer and the real volume which is usable space.

I'm referring to the difference between the summation of all the files I'm storing on the NAS (which comes down to a total of 8.15TB) and the capacity the system tells me which is already used (namely, 10.15TB).
So, I don't understand the gap beween those numbers: I'm literally missing 2TB of volume.

 

[Telos]

SSH in to your NAS with the “root” or "admin" account and password, then run the following commands:

1.

sudo -i

[Press Enter] (enter the admin password again)
2.

cd /volume1

[Press Enter] (change directory to /volume1 or any folder you wish)
3.

du -h -d1

[Press Enter] (list out the disk usage in each 1st-level sub-folder)

This should help locate the discrepancy.

 

[TorKnutzen]

Thank you Telos.
By looking at the disk usage via SSH as you indicated, I saw /@synologydrive which indicated 20T volume (I don't understand why this indicated a staggering 20T and not a simpel 2.35T which was the volume I was missing).
Then I found a post about this: Synology Community

I don't fully understand what I did wrong, but apparently by installing the Synology Drive application I probably (?) activated also the versioning of the shared Home folder, creating a full history of the files in a version DB located at /@synologydrive.

Anyway, uninstalling the Drive application resulted in deleting the version DB and as such giving back the 'missing' space of 2.35T !

A side note: I still don't understand why this is not simply 'visible' & 'controlable' in the Synology DSM environment, this would have saved my time and that of others...

 

[fredbert]

Synology Drive Admin Console has settings for how many historical versions are kept. It uses a database to that's not in a shared folder to hold and track these versions. Luckily you're using Btrfs file system as it is a lot more economical in this task than if your NAS had been built with a Ext4 file system.

You can change the values, and have different ones for user 'Mty Drive' and other Team folders (DSM shared folders). If you reduce the maximum versions then this will also purge the space that is being used by the database. Doing this will enable you to keep using Synology Drive, just dial down the versions and use Hyper Backup to make off-NAS backups.

The false 20TB size is likely due to something like image files that claim to be the size of the space they map, rather than the currently used space of their contents.