The A12S-G2130 is a SAS RAID array with 12 slots for SATA-II hard disks. It has two sister products, one with eight slots in a 2U chassis and the other with 16 slots in a 3U case. In the back are a pair of power supplies, along with a controller module and a slot for an optional battery backup unit. The controller unit hosts a pair of SAS connectors, plus an Ethernet connection and a pair of COM ports; the latter are perhaps the most bonkers RS-232 ports I’ve ever seen, as they’re actually 1.5mm jack connectors (think of the plug on your Walkman headphones and you’re spot on) – though in reality this isn’t a great problem as the appropriate cable and adaptor are supplied with the device.
Step one is to insert the hard disks into the unit. As you’d expect, the disks sit in trays that slide in and out of the front panel. Our review unit shipped with eight 250GB Seagate SATA-II disks and four empty trays; as with most arrays, you always have something in each slot so that the airflow inside the back of the case is preserved.
You can manage the unit in four ways. First, there’s a blue LCD panel with four selector on the front, and you can access the various parameters using this. Second, there’s a pair of RS-232 ports on the back, which allow you to point your terminal emulator at the box and manage it via a text-based menu system. Next, the on-board Ethernet adaptor gives a browser-based interface, which we found clunky but functional. Finally the accompanying CD includes RAIDWatch, a Java applet that runs on a desktop machine and provides a much richer way of managing the unit. To manage the unit via the LAN interface, you’ll need to set an IP address (or alternatively let it fetch one via DHCP), and we used the serial connection’s text-based system to bash in a static IP. For some reason the screens of text generated on the serial connection would jump up a line from time to time, so we had to keep refreshing the display in order to read stuff. This wasn’t too much of a problem since all we were doing was setting a simple address, but it would be a pain in the arse to use if we’d decided to manage the entire unit through the COM port.
The first problem we came across was that RAIDWatch wouldn’t run properly on our Windows XP client machine, which had version 1.5 of the Java runtime environment installed. When we ran it up on a second XP machine which didn’t already have a JRE, the setup process installed JRE 1.4.2_05 and then RAIDWatch, and all was well.
Once you’ve persuaded the Java applet to run, it’s very clear. The first screen presents you with a picture of the device, showing you the state of each disk and colouring the various disks so that it’s clear which disk belongs to which logical drive. The left-hand pane is split into three sections called Information (containing read-only volume/disk information and statistics), Maintenance (which lets you do some basic functions such as regenerating parity information and scans for media errors) and Configuration (full-blown control over disks, volumes and partitions). When you connect via RAIDWatch, you can log in under any of the three access levels (information, configuration or maintenance), though the Web GUI gives you only config or information levels.
Making disks into RAID entities is pretty simple, as the GUI is nicely graphical. You simply highlight the disks you want to use in your new “logical disk”, and select the RAID type from the pull-down menu (sensibly, it only gives you the RAID types permitted for that combination of disks, so you can’t do something silly like trying to create a RAID5 entity from just two disks). Creating the logical disks takes only a minute or so, though you can’t do further work such as partitioning them until the initialisation process (which can take many minutes) has finished. Logical disks can be partitioned (split into smaller sub-volumes) or made into “virtual partitions” (where you aggregate multiple logical disks into single virtual volumes). You can also map the various virtual entities into SCSI LUNs (SAS being a “virtual SCSI” protocol) for recognition by whatever host machines you’re connecting them to. Incidentally, you have a choice of write-through (changes get written straight to the disk) and write-back (changes are stored in RAM and written later), though without the optional battery-backup module the system forces itself into write-through mode (with write-back data would be lost in the event of a complete power failure).
Once we’d found our way around the device (which came with some preconfigured logical entities, so it took a minute to realise we had to unmap things before it would let us re-use drives and partitions) it was a breeze to use. Frankly you wouldn’t bother with anything but the Java-based RAIDWatch for management – aside from it not liking our main test machine, it was fine and very usable. The overview screens give a good representation of the device’s status, and if something disagreeable happens (such as a power failure in one of the inputs or a disk “failing” because I pulled something out) you’re told within a few seconds, and the on-board alarm sounds. (A nice touch, incidentally, is the “mute” button on the front panel – you can stop it screaming at you without having to connect via the management GUI!). Rebuilding a RAID5 entity after replacement of a failed disk took an hour and three minutes.
In short, then, the A12S-G2130 is a versatile SAS/SATA RAID array with a good desktop management tool, whose RS-232 and browser-based config interfaces are clunky but largely irrelevant anyway.
The EonStor is an attractive unit in the interesting (and growing) SCSI-to-SATA market; ignore the clunkiness of the serial and browser-based management interfaces, as you’ll use the Java one anyway.