Celerity FC-42XS and MediaVault 4210
Fibre Channel, like many technologies we use today, has gone through the traditional evolutionary process from big and scary to just another piece of wire. It's simple and well established, and so the only perceptible change in the technology, from the user's point of view, is that it gets faster from time to time – to 4GBps for the purposes of this review.
Obviously there are two ends to any Fibre Channel connection: the adaptor at the computer and the storage array it connects to. We looked at a new product in each of these categories: the ATTO Celerity FC-42XS adaptor and the MediaVault 4210 from the modestly named Huge Systems.
The FC-42XS is a dual-channel Fibre Channel adaptor which fits in a 133MHz PCI-X slot. Drivers are available for Mac OS X (10.4 Tiger and above), Windows (XP, 2000 and WS2003) and Linux (Red Hat and SuSE). Although it's a 4GBps device, it is backward-compatible with slower implementations. Installation is no problem – install the driver and configuration software and insert the card (in our case into a G5), reboot, and you're done.
The configuration application (available for all the platforms the card works with) is used to tweak the settings of the adaptor. The application identifies whatever Celerity cards are installed when you run it, and you're given a simple window into which you can insert the various parameters required to match it with your storage device – frame size, arbitrated loop versus point-to-point, and so on. Many of the changes you make in this tool require a reboot, but this isn't an issue as it's very much the kind of thing you'll set once and then leave well alone.
Once the adaptor's installed, you go to the other end of the cable. There are two products in the MediaVault range: the 4105, a tower unit with a single PSU, two-port 4Gbps Fibre Channel interface and five parallel-ATA drives; and the 10-disk 4210, which is effectively two 4105s in a single box, which operate independently except for the shared pair of hot-plug, redundant power supplies. The internal drives (all in easy-swap trays accessible via the pull-off front panel) can be 160, 250 or 400GB units.
Both MediaVault offerings have RAID 0 (striping) and RAID 3 (striping with one disk used to hold error-checking data) capabilities. Most of the storage arrays we've come across have a little configuration application that you use to set up your choice of partitioning and RAID on the unit. Not so with this one – there's a little switch on the back of the unit (or each half of a 4210) that lets you switch it between its six standard modes.
There are three basic modes: RAID 0; RAID “[email protected]” (RAID 3 with a 2,048-byte block size); and RAID “[email protected]” (as before, but with a 512-byte block). Each mode can be used with or without “Turbo” mode (which uses the highest-throughput portions of the disk first – presumably the bits near the edge), thus giving a maximum of six alternatives. To change mode, you turn the device off, select the mode, hold in the “Mode change” button, and restart – but beware, as any data on the disks won't survive the experience of a mode change. The lights on the front panel tell you the speed of each FC link and whether you're using RAID 3, as well as showing disk activity.
Once you've configured the array as you'd like it, the volume(s) you've defined are then visible to the host operating system and you can format them appropriately with the host operating system's own disk setup tools. The documentation says to run Apple Disk Utility, but of course before you get the chance to do so, Mac OS spots the unformatted disk and runs it for you. As with other arrays, such as Apple's Xserve RAID, the two independent sub-arrays in the 4210 can be further RAIDed using software RAID in the host OS or a RAID adaptor in the host server.