Top Trend - Edge Storage TestBy: John Honovich, Published on Apr 24, 2012
The top technology trend for Spring 2012 is edge storage, as selected by your fellow IPVM readers. While edge storage has slowly evolved it had never made a big push to the 'core' of the video surveillance market. Now, with a major boost by Axis plus new support from Exacq and Aimetis joining existing offerings from Genetec and Milestone, broader acceptance is increasing.
Potential for edge storage is clearly there:
- Traditional centralized recorders could be replaced by SD cards inside cameras.
- Cameras with low bandwidth or poor relaibility network connections can make use of edge storage. A good example is wide area wireless systems.
- Locations where only a few cameras are needed yet struggle to justify the cost of a full recorder can use edge storage.
- SD cards can be used for redundancy in case the recorder or network fails.
How Well Does it Work?
Since the technology is not broadly used, questions remain about how well it will work and how suitable it will be for traditional recorder replacement. Indeed our test results and many integrators experience with Mobotix's edge storage implementation, show that edge storage can introduce usability problems and delay in video retrieval.
Inside this report, we share out test results of Axis Camera Companion and Exacq Edge to better understand the performance, usability and application of these two new edge offerings.
Key findings from our test include:
- Generally smooth playback from SD card; storage source was transparent for both Axis and Exacq implementations
- Class 4 speed worked fine on a variety of cameras / resolutions
- Storage capacity was a concern for longer term or higher quality recording
- Fairly simple setup of SD card storage for both
While both Axis and Exacq's implementations worked well, the overall solutions are positioned at opposite ends of the spectrum:
- Axis Camera Companion is free, bundling edge storage with a new VMS with limited overall features. As such, it is best for simpler, smaller applications.
- Exacq Edge, while relatively expensive ($200 per channel) integrates into Exacq's overall video management line making it a high end feature of larger and more complex systems.
When evaluating edge storage, carefully consider how the feature is packaged as part of an overall offering, as the sweet spot could significantly differ. For instance, Genetec's edge storage feature, Trickling, supports advanced options and integrations that are a better fit for very large systems that either Exacq's or ACC.
Axis Camera Companion Test
ACC provides a entire turn key system not only for edge storage but for video management. The two most important take aways we found were that (1) the system is easy to use but (2) it has limited functionalities that restrict its applicability to more demanding use cases. Watch the video to see more:
Exacq Edge Test
The Exacq approach is fairly simple and works basically like any other Exacq recorder, except that it is physically running inside of a camera rather than on a PC:
SD Card Class Speed
While SD card speed is often cited as concern, we saw no issues. Both Axis recommended at least a SD card class of 4 (see backgrounder on classes/speeds). We could not find any cards at any local stores (inlcuding Wal-Mart) with a class less than 4 so there's not much practical risk or need to go lower. Even with a 4, we never saw any problems.
SD Card Manufacturer
We primarily used SD cards from Sandisk and had no problems with them. However, we had 2 'no name' cards and both had problems being recognized. Given that SD cards even up to 32 GBs are not that expensive, we suspect it's best to stick with a major SD card supplier.
SD Card Capacity
Card capacity, as expected, was a big issue. Most IP camera manufacturers, including Axis, only support SDHC that maxes out at 32 GB. That's the equivalent of a 16 channel 500GB DVR (i.e., 16 x 32). At those levels, one can fill up the 32 GB card fairly quickly. The 32GB limit is a hard cap. The only way to get around it is to use a NAS or switch to a camera supporting the SDXC format (see backgrounder on SD format options).
Equally important, keep in mind that Axis cameras default to variable bit rate plus their bandwidth will spike in low light scenes. If you assume the low day time bit rate Axis lists in its calculator, you can hit a very unpleasant surprise when you far too quickly run out of space. For more, see our review of Axis's streaming modes and why you should use Axis CBR option.
Finally, setup was rather easy for both systems:
- With Axis, as long as you use the wizard, all you need to do is insert the SD card into the Axis camera. Axis will format, configure, etc. The firmware/software is already built into the camera (assuming it is running 5.40 or later).
- With Exacq, it is a little more complicated but not much. An application needs to be added to the camera (as mentioned in the screencast above) plus the SD card needs to be formatted in the Axis camera web interface. Once done, the VMS / edge storage can be configured like any other Exacq recorder.
While NAS devices are not technically edge storage as they can centrally record from many cameras, they are a common compliment to edge / SD implementations that allow for recording more video for longer time periods without having to use a VMS / recorder.
We are doing a separate test of NAS devices. So far, we have found performance challenges to be more significant and more complex. We will report our results in a dedicated report in the next month.