ReadyNas 2304 Backup to ReadyNas2304 - Disk Consumption Differences
I have had a RR2304 in service for over two years, configured with 4x8TB WD Red drives with a single volume configured in RAID6, and two shares. Both shares are configured to snapshot daily. This is the production NAS.
I purchased a second RR2304 recently, and commissioned it with an identical hardware and volume configuration to serve as a backup to the production NAS and to function as a test-bed NAS and for semi-disposable data. It has three shares, two of which are not yet in use, and the third share is to hold the backups from the production NAS. No snapshots are scheduled.
I used the Backup config in GUI on the production NAS to migrate the data for the initial backup, then scheduled those backups to make them recurrent.
Here's the problem: The exact same data is consuming 6.97TB on the production NAS, but is consuming 8.72TB on the new backup NAS. I expected this to be the opposite considering the production NAS has scheduled snapshots. When I use the GUI to calculate the individual share sizes, the two shares on the production NAS total 8.7TB, but the NAS is calculating the consumption at 6.97TB. However, the consumption is being reported to windows as 6.97TB.
Re: ReadyNas 2304 Backup to ReadyNas2304 - Disk Consumption Differences
Do you have any links to files across shares? If so, your copy is likely actually copying the file to both places, not the file and link.
If the production NAS were old enough, I'd say it was due to a different sector size, but I don't think that's been updated in the past two years.
However, I have seen similar discrepancies, though not as severe as yours. I totally re-configured a NAS and restored from backup, and the resulting used space was larger. Like you, I calculated the actual use and found the newly reported volume use to be more accurate. I did not pursue the issue any farther, but I can see how an incorrectly reported use on you production NAS (assumning that's the case) could lead to running out of space before you expected to.
That I shared your experience doesn't really help you, but I hope it lets the Netgear mods know it's probably not unique to you.
Re: ReadyNas 2304 Backup to ReadyNas2304 - Disk Consumption Differences
That is helpful to hear, and I agree. It needs to get out there. There are no links to data across shares on the production NAS. There is repeated data, as I had originally scheduled a backup (using a different machine to calculate the sync) from one share to the other for "anti-user" redundancy in the event that individual files needed to be recovered. But to be clear, it is not linked, and it is a very small portion of the data. It sure looks like the first NAS is calculating usage incorrectly, at a very alarming disparity.
When I use the GUI to calculate the individual share sizes, the two shares on the production NAS total 8.7TB, but the NAS is calculating the consumption at 6.97TB. However, the consumption is being reported to windows as 6.97TB.
This is on the backup NAS?
I suggest doing a balance, and see if that resolves it. Space usage is a complicated subject with BTRFS, and it is possible that 8.7TB is somehow allocated, but only 6.97TB is actually used. A balance should take care of that.
