Drive Detection & Use:
- The Nx Witness Server application, once installed upon a computing device, detects and analyzes available storage during the setup process.
- Nx Witness will utilize all drives in a Server and writes concurrently to all enabled drives, so the more drives you have in a Server the less throughput you'll see on any individual drive.
- Nx Witness will not allow recording to drives that are less than 10% of the largest of all other drives in the system (e.g. an SD Card or USB Flash drive). For example, if a user has 10 TB NAS registered at some server all other drives with total space less than 1 TB will be disabled for recording at this particular server. This is done to ensure a correct write-ratio calculation and to improve 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).
General Nx Witness Write-to-Archive Process:
- 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 more details by reading our article about adjusting reserved disk space.
- 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 a solid timeline is guaranteed.
- Since 2.6 version Nx Witness prevents recording onto the system drive if there's any other storage drive installed on the server which meets the minimum requirements and is 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
- If Failover-on-Hard-Drive-Failure is enabled the cameras writing to this drive will be moved to a designated Failover server (starting in v4.0).