The TeraStation Comparison Chart summarizes the Tera III's feature set, most of which (aside from RAID) is shared by the LinkStation Pro XHL. Consult the Pro XHL review and slideshow if you want more detail on the common features. The Tera III slideshow has screenshots and descriptions of its unique features.
Figure 4: TeraStation Comparison Chart (partial view)
The high level summary is that you can think of the Tera III as a four-drive RAID 0 / 1 / 5 / 10 version of the LinkStation Pro XHL that supports joining NT domains and Active Directories for user account information.
This means that the Tera III includes UPnP AV / DLNA and iTunes media serving as well as BitTorrent downloading—a bit odd for a product aimed at small businesses. But given that the competition has taken the approach of offering similar consumer features and more across their entire product lines, this is a move in the right direction for Buffalo.
Also shared with the Pro XHL are the Tera III's backup features. So it can do immediate or scheduled back up to an attached USB drive or another networked LinkStation or TeraStation. Also like the XHL (and other Buffalo NASes) backups can be encrypted, compressed or both. The III can format USB drives in FAT32, EXT3 or its native XFS and supports read and write to all three. It will also mount an NTFS-formatted drive for sharing, but not write to it.
As with other Buffalo NASes, you get one license for Memeo Backup, which is rather stingy, given the multiple (and sometimes, unlimited) backup client licenses offered with other products.
The Tera III's user interface is the new AJAX-based one used by the LinkStation Pro XHL, vs. the older style used in the TeraStation Pro II. Unfortunately, the III's interface shares the shortcomings of the Pro XHL's, i.e. no logging and meager status information. This time, however, I was able to get email alerts working, which is probably due to my enabling the III's TLS option, even though my SMTP server supposedly doesn't use it.
The III's unique features (vs. the LinkStation Pro XHL) include:
- Support for eight Distributed File System (DFS) links for SAN-like storage expansion
- Port trunking options for the dual Gigabit Ethernet ports including independent, redundant, auto-failover and multiple aggregation modes
- NFS support
- JBOD, RAID 0, 1, 5 and 10 support with hot spare for RAID 1 and 5. Two arrays are supported, but with only four drives, options are limited. RAID 0 is supported only for four drives and only RAID 1 can be configured for two drive use. You can have a three-drive RAID 5 array, however.
- Drives and RAID arrrays can be optionally be 128 bit AES encrypted
- TeraSearch function that creates an index of files in selected folders to support a filename search function.
RAID Fail Test
I performed a pull-a-drive test on a three-drive RAID 5 array configured with a hot spare. After starting a large folder transfer to the Tera III, I pulled the #2 drive. Within 5 seconds of pulling the drive the LCD panel flashed red and the internal beeper sounded for around 10 seconds. When I checked my email about 30 seconds later, I had received 15 messages telling me about various drive and volume errors. I then logged into the NAS and was taken taken to a page that told me that a volume rebuild was in progress (Figure 5).
Figure 5: Login landing page after hot spare swap-in
I should note that the file copy was temporarily interrupted about 30 seconds after the drive was pulled. But when I checked to see if my data was still there, I found that it was and that I could again read and write files to the Tera III's share.
The main negatives in the process were that I did not receive an email notice that the hot spare had been swapped in and the rebuild started. The LCD panel also doesn't automatically switch to show that a rebuild has started, nor does it display % completion of the rebuild. I did get an email, however, when the rebuild finished, around four hours later.
After the rebuild completed, I then pulled the #4 drive on the new three-drive RAID 5 array, which now had no hot spare. Once again the LCD panel flashed red and the beeper sounded and multiple email error notices were sent. But this time when I logged into the Tera III, I landed at the normal Shared Folders page, with no indication that anything was amiss. I had to navigate to the System > Storage page and open the RAID Array section to find an Error status.
When there is no hot spare set up to swap in, you must inititate a RAID rebuild manually. So I reinserted the #2 drive (the one pulled in the initial test) and immediately saw the LCD panel turn red and display a Press FuncSW New disk2 ready message. My first button press had no effect, so I consulted the manual and found that I needed to press the Function button until I heard a beep to release it.
At this point you need to be patient, since the panel switches back to the default Link Speed screen (but remains red) and you won't see any rebuild indication on the System > Storage > RAID Array page if you check it right away. But about three minutes later, while I was wondering what to do next, I heard the Tera III's drives start to chatter.
When I then checked the RAID Array status, it showed that the rebuild had started. But the LCD screen took another minute to catch up and turn back to its normal blue color. Finally, I received three pair of emails saying that rebuild had started then completed, plus one additional rebuild start email. I then finally received a rebuild finished email about four hours later.
So the RAID rebuild process seems straightforward enough. But, as noted, you do need to be patient since it takes a few minutes for the LCD panel, web admin interface and email status to all get updated.