Disk storage is notoriously fickle. One minute your drive is humming happily, and the next it's screaming like a banshee and trying to turn into a lathe - or simply dies. Whatever the issue, at that point the unprepared probably will start swearing, invoking the gods of hardware, sacrificing chickens and, eventually, drinking heavily. We did.
A few weeks ago we were testing some software on our Apple G5 and we were running out of disk space. It was urgent we get the project wrapped up.
We remembered that we'd been sent a really cool storage subsystem that was still in its box, and we suddenly felt guilty, because the product was one of those review projects we'd planned to tackle - over a year ago.
We figured this was a good time to try the device, a Kano SureVault800-360. The SureVault is a 360GB RAID 5 storage system (priced at US$1,139) that supports Firewire 800, Firewire 400 and USB 2.0. The device works with Windows and Macintosh PCs (it is formatted by default for Macintosh).
Because the SureVault supported RAID 5 it was just what we were after; the data we needed to move off the Mac was our photo collection, which, you will remember from previous BackSpin columns, is rather large (it's now up to around 16,500 images totaling around 20GB).
RAID 5, we're sure you remember, is where data is striped across several drives at block level, with parity also being copied across the drives. In the case of a single drive failing, the complete data set can be rebuilt without data loss. Because most of our photos are irreplaceable we figured this was an excellent solution. What could go wrong?
We unpacked the SureVault, gave the manual the cursory once-over, plugged in the power, connected it to the G5 via the Firewire 800 port, switched it on and, lo and behold, the SureVault worked! Amazing. The SureVault over Firewire 800 is really fast, but the fans are a little noisy.
We moved the photos off the G5's internal drive onto the SureVault, and everything was fine - until a few days later.
The Firewire cable connected to the SureVault was pressed against the wall, and suddenly the SureVault didn't work. The pressure of the cable against the wall had stressed the connectors on the subsystem's input/output board and the Firewire connector popped off (the latest SureVault units are engineered to prevent this problem).
We tried the other ports but the subsystem wouldn't mount at all. When we ran OS X's Disk Utility it could only tell us that the volume header was invalid and couldn't be repaired. In fact, the Disk Utility error message is useless and is as unhelpful and opaque as only a *nix utility can be. Apple should be ashamed.
We got in touch with Kano - which has outstanding technical support - and it sent a new chassis. After transferring the drives, we fired the subsystem up and - nothing. Still an invalid volume. The probable cause was that as the connector popped off the board, it generated a spurious write and, blat, we got a corrupted disk.
Kano suggested we try Alsoft's DiskWarrior utility, which is priced at US$80.
To run DiskWarrior you have to boot your Mac from the Alsoft disk. Once the program loads you can see all attached drives, graph their fragmentation, and recover and rebuild directories. DiskWarrior also can install a disk monitor that loads at start-up and monitors all Advanced Technology Attachment drives that have Smart support and notify you when critical conditions occur, such as high temperature or too many errors. We let DiskWarrior do its magic and in about five minutes we were back in action.
So, even high-reliability storage subsystems can be less safe than you'd expect. You shouldn't expect the operating system tools to help and you'd better have the right third-party tools on hand if you plan to recover.
The Kano SureVault is a little pricey but it's fast and extremely reliable. DiskWarrior, for the pain it can save you, is inexpensive and absolutely vital to your happiness.