data and settings missed after one month from NVR

dear all
i have IP camera system currently installed in our office
i have 6 IP camera from D-link connected to our network
and managed by D-view cam program , all data stored in
 D-link  NVR model DNS-722 , the system worked fine
for 20 days after that we found all data missed from NVR unit
 , this problem happened with us twice till now
so could you please advise ?
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David Johnson, CD, MVPOwnerCommented:
perhaps someone deleted the files? check who has access to other than view and restrict the access to 1 user ONLY

Do daily checks, you may want to use forensic tools to see if the files are still on the hard drive
David Johnson, CD, MVPOwnerCommented:
or are you saying anything older than 1 month is deleted?
nettech1998Author Commented:
all recorded files inside NVR suddenly disappeared after 20 days  , i think the problem happened when the Hard disks reach it is full capacity so the NVR overwrite features does not work correctly at this time so the data lost  is that logic reason please advise ?
David Johnson, CD, MVPOwnerCommented:
If the hard drives run out of space then it is logical that files will disappear.. if you need to keep them for posterity you need to archive them

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