Long Term Storage / Digital Tape (Soleratec)By John Honovich, Published Jun 26, 2011, 08:00pm EDT
Long term retention requirements and large camera counts can result in expensive storage systems. Users look to a variety of techniques and options for minimizing storage costs and size. In this note, we examine one approach - Soleratec's RSM [link no longer available] offering combined with digital tape storage. We then contrast its strengths and weaknesses to network based storage and storage optimization techniques (such as frame pruning, transcoding, etc.).
First, Soleratec's general approach is uncommon for video surveillance so understanding the differences are important to start:
- Soleratec is neither a VMS/NVR nor storage manufacturer. Rather, it is a middleware software application that integrates with VMS/NVRs and separate storage appliances.
- The two key functional differentiations of Soleratec are: (1) it manages off-line storage such as digital tape and (2) it creates and provides a reduced quality online video stream (called companion files) for users conducting searches on a VMS application.
- The key financial / business drivers are that: (1) off line storage such as digital tape is dramatically less expensive than online NAS or SAN devices and (2) that the reduced quality companion files minimize the need to access the offline recordings. Review Soleratec's cost advantage brochure to see their pitch.
- Pricing: Soleratec charges for on-line storage ($1,495 MSRP for 4TBs) and data tape storage management ($595 for 4TBs). Soleratec does not charge for offline storage. This approach may be confusing to surveillance buyers as it does not follow the common per channel or simple storage model. The assumption with Soleratec is that most of one's storage will be kept offline. Users would only pay for the minority of storage that is kept online.
- Integration: Soleratec reports integration with Milestone and OnSSI [Note: an earlier version erroneously cited integration with Exacq and Genetec]. The integration allows transparently transferring recorded video from the VMS to Soleratec's video management system. Once video is transferred to Soleratec, operators need to use Soleratec's application rather than the VMS.
Soleratec Operational Aspects
The biggest operational difference is the presence of off-line storage. In today's video surveillance, almost all storage is online (whether in a hard drive inside the recorder, in a NAS, SAN or in a SD card on a camera, etc.). With Soleratec, the assumption / value is that most of the storage is copied on to digital tapes and then archived.
The offline digital tape approach raises some of the same concerns surveillance users traditionally had with VHS tapes. Periodically, an administrator needs to remove, archive and replace digital tapes from the digital tape library. Additionally, if a user or investigator wants to access the original full quality recordings, just like a VHS, they will have to find and insert the tape (rather than simply press play with a traditional VMS). On the other hand, Soleratec's online low resolution companion files are designed to minimize the need to retrieve the offline video. Nonetheless, despite the likely lower infrastructure cost, some increase in operational expenditures and coordination are inevitable with the Soleratec approach.
Strengths and Weaknesses
Let's review key strengths and weaknesses that should be considered:
- Per TB storage pricing will be significantly lower. Not only is digital tape less expensive than hard drives, offline digital tapes require no additional infrastructure unlike hard drives that need to be managed by servers, NAS or SAN appliances.
- Power and HVAC costs will be lower as the tapes are offline and essentially powered off. That noted, we expect the bulk of the potential savings to come from eliminating servers, NAS or SANs rather than power and HVAC.
The strengths are essentially lower cost. We do not see any potential for improved investigations outside of the lower costs allows for longer storages which might solve cases otherwise lost.
On the weaknesses:
- Searching of video: All video managed by Soleratec needs to be searched from the Soleratec user interface. This requires the operator to switch from the Milestone or OnSSI clients to the Soleratec client, increasing the complexity and requiring learning of a second application.
- Accessibility of video: The additional step of needing to physically find and load offline video may reduce the desire or ability of investigators to conduct investigations (e.g., an investigator may need to find a tech admin to locate and load the video they need, this person or storage could be at a different site, etc.).
- Greater complexity: This solution requires integrating a VMS with a new application and often hardware types that an organization has not used previously.
- Start up costs: For smaller systems, the greater complexity and the need to have a additional hardware component (the offline media recorder/player, e.g., the digital tape library) adds a non trivial start up cost.
The other major issue is that alternative techniques that might be easier to implement and provide similar value:
- Frame pruning: The frame rate of older video can be dropped. For example, new video can be recorded at 30fps and old video only at 3fps, saving 50% or more in storage while keeping it online. This depends on the vendor's support, CODEC used, etc.
- Multi-streaming recording: The VMS can receive two streams - a higher and lower quality one. The higher quality one can be used for short term storage and the lower one for longer term storage. Same issues apply as for frame pruning.
- Transcoding: A few VMS systems, such as TimeSight, will periodically re-encode video to reduce its storage consumption. This requires the use of a single VMS.
This noted, as we have not tested the software, a number of unknowns exist that should be considered:
- How easy is the integration with a VMS?
- How tightly integrated is Soleratec with a VMS?
- What is the actual quality and usability of the companion files? The better, the less need there is to access offline storage.
Given that Soleratec adds complexity, some start up cost and potential concerns of easy video access, we believe the solution is best for organizations wanting very long term storage yet is unlikely to need the video. For organizations with industry or government regulations for quarters or years of video storage, this may be a good fit. In those cases, the video is more an 'insurance' against unknown risks and the practical concern of retrieving offline video is low. By contrast, organizations only keeping video for a short term (like one or two months) who are likely to access older video repeatedly might be better off with traditional offerings and optimizations. Finally, an organization who traditionally stored only short to mid term but wants to explore much longer term storage may see Soleratec as a low cost option to enable longer term recording.
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