The server can run many applications at the same time. In fact there's no limit to how many it can handle, but, like any computer, the more you have it run, the slower it'll get. For that reason, the server comes with few built-in apps. These apps as well as others can be removed or installed via the Package Center. Since I can't review all these apps, I'm only discussing here those that I feel most users would appreciate, which are the Download Station, Cloud Station, Surveillance Station, and Photo Station.
The Download Station enables the server to download files from the Internet by itself, from any FTP and HTTP sites, including sites that require authentication, such as RapidShare. It's also the best BitTorrent application I've seen that lets you search for what you need and and download it with a click. There's no need to download the torrent file from a separate Web page and load it, even though you can also do that with the Download Station. You can tailor the Download Station to use a certain amount of bandwidth and to avoid certain types of content, such as those that could pose a copyright infringement violation. There are also many other ways to customize the way it works.
The Cloud Station works similarly to the Dropbox service but much better. Once the application is run, you'll be given an EzCloud ID (you can choose your own as long as it's still available). This ID needs to be unique for each server. After that, you can download and install the Synology Cloud Station for your PC (running Windows XP or later) or Mac (running Mac OS 10.6.8 or later), run it, and enter the EzCloud ID and the user name and password for your account on the DS412+ server. After that you can sync data from the computer, no matter where it is, as long as it's connected to the Internet and to your DS412+ server.
There's no limit to how many computers you can use for syncing and how much data can be synced, as long as it doesn't take up more than the available space on the server or the quota of the account. The only limit of the Cloud Station is the fact that it won't sync files that are larger than 1GB. However, this, in a way, is a good thing; 1GB is very large for a single file, and we're talking about moving data in real time over the Internet here.
Note that each user has his or her own folder for the Cloud feature, meaning that multiple users can sync their own data without affecting one another. The DS412+'s Cloud Station supports up to 32 accounts. If you have a fast Internet connection, you can even start a small online storage service this way. The Cloud Station feature alone makes the DS412+ worth the investment. In fact, it's about as easy to set up as Dropbox, but it offers more online storage space and better control over your data, and doesn't carry a monthly cost.
The Surveillance Station supports 20 IP cameras. This means you can use the NAS server as a video recorder and management station of a very comprehensive surveillance system, again, possibly the best I've seen. I tried the server with multiple IP cameras from Canon, Vivotek, Y-cam, and Trendnet, and they all worked very well, individually or together. I could record images based on scheduling or motion detection. When multiple cameras were used, I could even synchronize the playback to see what happened at different cameras at a given time. The Surveillance Station supports all features of the camera, such as night vision, pan, tilt zoom, and audio. The server doesn't support every IP camera on the market, however, so make sure you check the supported list before getting yours. There's also a free DS Cam mobile app for iOS and Android devices that people can use to monitor and manage their Surveillance Station while on the go. The mobile app worked excellently in my trials.
Unfortunately, most users can't make multiple cameras work together out of the box. This is not because the Surveillance Station is hard to set up -- it's actually very easy and automatically finds and adds supported cameras to the network for you -- but because there's only one camera license included with the server. To use more than one camera, you'll need to buy additional camera licenses that cost about $50 each. This potentially makes the DS412+ a lot more expensive if you wish to use it as a surveillance system.
The Photo Station lets you easily organize photos into albums. Once activated, a share folder called "Photo" will be created. Photos stored in this share folder will be automatically placed in well-organized, customizable albums, one for each subfolder. You can then browse the album via a Web browser, like a Google Picasa Web album, and very easily add captions and comments to each photo or album. The Photo Station also offers a complete blogging engine for those who want to chronicle their lives with photos and text. And like the Surveillance Station, the Photo Station comes with a mobile app called DS Photo for both iPhone and Android platforms. In my testing, the Photo Station took a rather long time to generate photo thumbnails, which would be a problem if you wanted to add a large number of photos at a time. If you want to add fewer than 100 photos at a time, you won't notice the slow thumbnail-building time.
Other than these, there are many other useful and effective applications for the DS412+, such as Time Backup, which makes backups of data on an external hard drive; a VPN server; an Audio Station; a DLNA/UPnP Media Server; and so on. The server can also run applications developed by third parties and comes with mobile apps for both iOS and Android devices.
All in all, I believe there's virtually nothing you could want from a NAS server that the DS412+ doesn't offer.
I tested the DS412+ both with Hybrid RAID and RAID 0 and it offered stellar data rates. In Hybrid RAID, the server scored 105MBps and 104MBps for writing and reading, respectively. In RAID 0, it did slightly better with 110MBps and 107MBps for writing and reading respectively. Note that the server was tested using a single Gigabit Ethernet connection. It potentially can offer higher performance when both of its network ports are used at the same time.
All in all, the DS412+ offered one of the best, if not the best, data rates among NAS servers I've tested. It's in fact faster than many USB 3.0 external hard drives and even comparable to some Thunderbolt drives. The server also performed very quietly; the only mild noise I could hear from it was that of the internal hard drives.
(Longer bars indicate better performance)
Service and support
Synology backs the DS412+ with a two-year warranty from the date of purchase, which is the same warranty the DS410 gets. Phone tech support is available Monday through Friday, 9 a.m. to 5 p.m. PT. Synology's customer support is generally very responsive and helpful. At its Web site, you can find its forum, download software and the latest firmware, and get more information about its products from its wiki page.
Those with advanced network and storage needs will find the DS412+ the best four-bay NAS server on the market to date, both for small-business and home environments.