DataDirect Networks Surveillance Storage OverviewAuthor: Ethan Ace, Published on Nov 01, 2011
The question of how to handle large amounts of video data is key in the surveillance industry. Historically, integrators have stuck to general IT storage providers, such as EMC and Dell, though surveillance-focused products such as Intransa and Pivot3 have gained some traction. Best known in the IT industry for high-capacity, high-performance storage systems, DataDirect Networks is relatively unknown in surveillance. In this update, we will examine their line and see how it compares to the surveillance-focused lines, and when users would likely choose this line.
DDN essentially has three levels of product for surveillance, with feature sets and price tag both increasing as you scale up:
- S2A6600: The low end of the DDN line, the S2A660 consists of a 60-drive 4RU enclosure which scales up to 120 drives in a second enclosure for a maximum of 360TB. DDN uses 3TB drives as standard today.
- S2A9900: The S2A9900 is the mid-range of the DDN line, and scales up to 1,200 drives, a max raw capacity of 3600TB, or 3.6 Petabytes. The 9900 is also intended to be fault-tolerant. DDN reports it is capable of losing up to 20% of its drives without loss of performance.
- SFA10K: The 10K series is actually comprised of two models, the SFA10K-X and SFA10K-E. These two models are similar in capability to the S2A9900, with some additions. First, instead of being limited to 3.6PB, the SFA scales up to "dozens of PB", according to its specs. This is accomplished by aggregating multiple systems of 3.6PB each. Second, the SFA10K-E is capable of running VMS software on VMs, so no additional servers are needed.
All enclosures are capable of spinning down unused drives when they are not in use, for a claimed energy savings of up to 80%. Compared to the two commonly-cited surveillance storage providers, Pivot3 and Intransa, DDN is also much higher density. Both of these competitors provide only 12 drives in a 2U enclosure, or 24 drives in 4U, less than half the density of DDN's 60-drive enclosures.
xStreamScaler File System
One feature which the entire line shares in common is the ability to use DDN's proprietary xStreamScaler file system. xStreamScaler differs from NTFS (typically used in SANs) in a number of ways, which DDN claims results in the several performance and feature enhancements.
First, it allows for more efficient writing of files by using a variable write size. Where NTFS only writes in 4Kb increments, xStreamScaler can write in larger sizes. Upping writes to 512Kb is a 128x increase in write speed. This increase reportedly allows more cameras to write to a single storage unit without errors. We have not tested these performance gains, so we can make no claims as to their veracity.
Second, xStreamScaler allows for multiple media types and off-site storage to be used based on policy. It allows for a mixture of SATA, SAS, and solid state drives to be used, whereas SANs normally use only one type. Files may be moved by retention policy to different drive types, which allows files of a certain age to be saved to tape or stored off-site.
VMS Partners and Integration
DDN has a short list of VMS partners on their website, including DVTel, Genetec, and Milestone. These are the partners that DDN has been tested with. However, since the line can be run as standard SANs, any VMS should be capable of using it with the NTFS file system. Not every VMS is capable of utilizing their xStreamScaler file system, however. Software platforms which are only capable of writing to local drives, and not shared mount points can only use the DDN line in SAN mode, which leaves them unable to utilize the xStreamScaler file system and potential benefits.
DDN Competitive Comparison
Pricing ranges from $800 to $1,000 per terabyte presuming a fully populated system, with price per TB decreasing as system size increases. A single-enclosure (60 drives) S2A6600 has an MSRP of about $180,000, or about $1,000/TB. Extending that system to the full 120-drive limit increases the MSRP to about $313,000, or about $870/TB. A 600-drive, 1.8PB SFA10K-E system has an MSRP of approximately $1,475,000, or a cost of about $820/TB.
Based on budget and capacity, systems requiring this amount of storage are uncommon. To require petabytes or even hundreds of terabytes of storage, the deployment would have a very large camera count, likely in the thousands, very long retention periods, or quite possibly both. The most likely candidates would be large municipal or critical infrastructure systems.
Compared to other products in the surveillance industry, DDN is obviously targeting the high end. Where companies such as Pivot3 and Intransa have traditionally offered smaller drive count enclosures, such as 4-, 8-, and 12-bay units, in capacities as small as 4TB, DDN's minimum entry point is a 60-drive enclosure with a capacity of 180TB. On the high capacity end of the spectrum, Pivot3's largest storage unit has a capacity of 288TB of raw storage, which falls in the range of DDN's 6600 model. Intransa has added the VA600st storage appliance which has a maximum capacity of 1.5PB, more in the range of DDN's high-end offerings.
Intransa and Pivot3 have also pushed embedding the VMS on the same platform as storage at even the low end. In order to take advantage of this feature, users need to go to DDN's top-tier platform, with a price tag normally over $1M. Users seeking integrated storage and server would likely find a better fit in more common lines, unless the system requires petabytes of storage.
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