How we use our hard disks

The concept of data striping within RAID system is key to spreading data amongst the disks so that should one of the disks fail not all the data is lost. Below is an example of striping, the data is shared equally between the disks.

Stripe2

Striping is used by Mirasys to provide a robust and reliable recording platform. Mirasys does this using Secure Data Distribution (SDD) storage. The Mirasys SDD technology distributes video frames evenly between drives (this does mean more than 1 drive is needed with a optimal amount of 3-4 disks).

A single drive failure would only decrease frames on a video clip and not leave any large blank areas during the storage interval. This can mean a well-placed, good resolution camera gives practically the same success rate with a low frame rate as a video with a higher frame rate – meaning that the risk of not being able to analyse an event due to a failed hard disk becomes close to zero.

The SDD system can be shown easily with an example using four disks D:, E:, F:, and G:. The video data would look like this:
RAIDConcepts1
If we assume drive F: has failed, the data would look like this:

RAIDConcepts2

Even with 3 out of 4 fail disks we would still have little problem viewing the footage:

RAIDConcepts3

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