I have a SmartStor DS4600 DAS. It contains 4x1.5TB and it runs as Raid5, so I have about 4.5TB to use. It works well with USB/eSATA on my Ubuntu 10.10 (and now with my 11.04) Desktop PC, and it also works well on the GuruPlug with USB/eSATA. To make the DAS work with my GuruPlug, a few Steps were needed.
Setting up the DAS was made with the software (called SmartNAVI) that comes with the device, of course only for Windows and Mac OS X. It gives the possibility to set up a Raid-system with Raid 0, 1, or 5 and provides some other system settings. However, it is important to know that a storage device > 2TB can not be formatted using Windows XP, since Windows XP can not handle drives > 2TB. Thus, some other operating system which supports larger (GPT) partition tables has to be used, like Windows Vista, Windows 2003/2008, or Windows 7 (thus any Windows newer than Windows XP). I'm not sure about Max OS X, but newer versions should definitely work.
The SmartNAVI software then makes it easy setting up and formatting the required Raid-system. After the setup is finished, the Raid-system is ready but it is formatted with NTFS. Since it will be used only on a Linux system (Ubuntu), I prefer ext4 as file system. Just connect the DAS to your computer runnning Linux and use a tool like GParted to format the system with your preferred file system. All the Raid-functionality is handled within the DS4600, so it appears as a regular hard drive to your computer and formatting works like with any other hard drive.
Connecting the DAS with USB was no problem at all. Plug it in and mount it to your desired mount-point.
When I tried to connect the DAS to the GuruPlug with eSATA, I ran into some problems (which were easily solved with the second scenario).
The GuruPlug is off and the DAS is in stand-by mode (it turns into stand-by mode automatically if USB or eSATA is unplugged). After plugging the GuruPlug in, the boot process starts. Once during the boot process, the eSATA power goes up which triggers the DAS to wake up from the stand-by mode. The problem which occurred here is that the DAS needs quite a while to be ready. The following messages appear a few times while the DAS is getting ready, but it gives up trying before the DAS is ready
ata1: link is slow to respond, please be patient (ready=0) ata1: SRST failed (errno=-16) ata1: limiting SATA link speed to 1.5 Gbps ata1: SRST failed (errno=-16) ata1: reset failed, giving up
At the end of the boot process, when it tries to mount the devices which are listed in /etc/fstab (I already added the DAS per UUID, so it does not need any changes compared to when connected over USB), the following messages appear:
uncorrectable error : end_request: I/O error, dev mtdblock0, sector 216 uncorrectable error : end_request: I/O error, dev mtdblock0, sector 224
and it continues with many more messages which have a different sector number, ending with the message that the device which it tried to mount is not available.
The solution I see here would be to either add a timeout somewhere during the boot process, so that the DAS has enough time to get ready, or to increase the number of attempts to do the reset.
The GuruPlug is already running and I start the DAS manually. The god thing: eSATA is hot-swappable and it acts like plugging in a USB-device. After starting the DAS manually, some messages appear on the serial console and as soon as the DAS is finished with the start-up, it can be mounted easily.