Updated: May 5, 2020
Every client has a questionnaire ready for their surveillance system designers and installers. But one common query that replicates across all those different question sets would be, "Why do we need to invest on a surveillance hard disk?" A very valid concern unless answered, to the satisfaction of the client. We would like to discuss the basic differentiations that make surveillance hard disks suitable and irreplaceable for your security solutions. For explanation purpose, we would take the example of Seagate SkyHawk Series Hard disk and compare that with a normal PC hard disk.
Understanding the Usage:
Before getting into the technicalities, one need to understand the changes in the usage pattern between PC hard disk and surveillance hard disk. A PC hard disk would be used nominally for 8 hours per day, with work and sleep modes alternating. Surveillance disks would be running all around the day across the year non stop 24 X 7 X 365. Similarly the data access from a PC hard disk is usually read and write alternating frequently during work time. But data access from a Surveillance hard disk is predominantly write only. Reading from the hard disk happens only when we try to view the recordings or backup recordings to any other storage media. Since we would like to roam around the basics revolving around the choice of hard disk for a commercial use, we are not getting into RAID like concepts and NAS like options. We shall discuss them as a separate blog in details. So quickly in layman terms,
Before getting to seeing the technical aspects one by one, we shall summarise the features available in SEAGATE SKYHAWK surveillance hard disk, which would eventually help us in explaining the differences.
Heavy writing (90% write and 10% read)
Capabilities upto 8 TB, with 16 drives with RAID and 64 HD camera support
Image Perfect / Skyhawk Health management / Optional Rescue data Recovery service
Rotational Vibration Sensors (RV) and AcuTrac technology - minimises the effect of multi-bay environment
Organic Solder Protectant (OSP)
Upto 1.5M hours Mean time between failures (MTBF)
Tarnish resistant components
As discussed in the usage section, surveillance hard disks predominantly are designed for more of writing than reading responses. In case of Seagate, it is designed for 90 % write and 10% read, A heavy write literally means more details are captured
Workload factor is the total amount of data written to or read from a hard disk. It is often related to daily load of data access know by 'operating duty' of a hard disk. PC hard disks with their daily operating duty of 8 hours account to a 55 TB per year work load. But in the case of surveillance hard disks, it is a round the clock operation and hence, it should be thrice the work load at least. Reputed brands like Seagate, Toshiba and Western Digital (WD) offer surveillance hard disks that have a normal work load of around 180 TB per year, which are efficient enough to stand the rigorous life cycle of Surveillance.
Firmwares and Softwares:
Surveillance hard disks come with dedicated firmwares and softwares to handle to different operational challenges. ImagePerfect is one such firmware with its features, ensures enhanced surveillance streaming and playback, with upgraded data protection. This is a proprietary feature of Seagate SKYHAWK Series. Then there is the Skyhawk Health Management (SHM) feature that leverages its operations around the prevention, intervention and recovery of data hazards involved with a hard disk. This software uses the host system processor like the NVR module processor for operation and is compatible with most reputed brand NVRs available.
MTTF or MTBF:
MTTF - 'Minimum Time to Failure’ or MTBF - 'Minimum Time between Failure' is the factor used to measure the longevity off any hard disk based on the time taken to record first failure of any hard disk. Normal hard disks are designed to have this factor at around 0.3M which means there is a possibility of one hard disk failures among 300,000 hard disk population. In the case of Surveillance hard disk the possibility becomes very less comparatively. For example a Toshiba V300 Video Surveillance hard disk comes up with a MTTF of 1 Million hours and a Seagate Skyhawk Surveillance disk comes up with a MTBF of 1.5 Million hours
Apart from these there are additional factors like sensors that protect from vibrational and physical challenges. High graded components and OSP that provides an additional layer of physical protection assurance.
Here is an hard disk selection guide that give more data specific to your requirement:
Author: Antony Kavin B, Certified Surveillance Expert from Seagate Champions Program