The Nx Witness Server application detects and analyzes available storage during the setup process. Nx Witness will utilize all drives in a system which fit special conditions. Drive will be considered as suitable for recording in case if it at not less than 10 times smaller than the largest drive attached to server.
So for example if user has 10 TB NAS registered at some server all other drives with total space less than 1 TB will automatically become unavailable for recording at this particular server. Server does it for the sake of correct write ratio calculation and overall system stability.
External storage drives can also be assigned via the Nx Witness client. Storage options include local storage to the HDDs available on the server computer, Direct-Attached Storage (DAS), and Network-Attached Storage (NAS).
The Nx Witness recording process goes a little something like this:
- IP Video camera streams are detected and captured by the Nx Witness Media Server and stored in RAM.
- The Nx Witness Server writes captured IP video in RAM to available storage (internal hard drives, DAS, or NAS) once per minute..
- All suitable drives are written concurrently and according to a ratio the system calculates for their size. So, for example, if a single server has multiple sized hard drives Nx Witness will fill up each hard drive at the same rate to ensure that no single drive's system bus gets overloaded.
- Nx Witness keeps some free space at every drive so that performance is not affected. You can find details about Nx reserved space here: https://support.networkoptix.com/hc/en-us/articles/229345767
- When a drive is full Nx Witness will then begin to overwrite non-locked video starting with the earliest (oldest) video on the server across all drives. Thus solid timeline is guaranteed.
- Since 2.6 version Nx Witness keeps system drive blocked for recording if there's any other drive at server which fits minimal requirements and at least 5 times larger than system disk.
- User can not manually modify the archive(delete/add/etc.) using Nx Software
How is hard disk failure managed?
If a single drive in a multiple drive system fails the Nx Witness system will do the following:
- continue writing to all available drives
- create a notification in the notifications panel that a hard drive failure has occurred
- rebuild the archive index after the Media Server is restarted