Real World Computing
A tale of two Linuxes
I like my network appliances - to my mind, there's little point wasting resources on a full-blown server operating system just to perform some simple repetitive little task, and I'm sure I can't lose any more friends by admitting that I think the best OS for your network appliance is Linux. For a long time I've lived happily with a stack of devices that present themselves to me solely through a configuration page in a tiny website. Such solutions are nowadays becoming ubiquitous. You buy a small box, plug it into your network and watch your DHCP server dispense a fresh lease, then hop to that address in your browser: it's become almost a habit. Print servers, firewalls, routers, home controllers, all of them pop up web pages, and the less you know about what lies behind them the better.
Perhaps the most popular and noticeable of these - the small NAS box - has recently got too big for its boots, though. These days, it's common to find a terabyte or two of disk supervised by a tiny CPU running a minimal Linux ruthlessly cut-down from some larger distro. This month, I mostly seem to have been tripping over Buffaloes: not the animals, but the appliances. One especially angst-ridden call came from a client who was doing something I expect is exceedingly common now: running a Buffalo NAS box in his network with Acronis Echo (www.acronis.com) installed on all the workstations.
Echo, and indeed preceding Acronis versions, mix and match their technology platform. You get a group of Windows utilities that snapshot your entire partition or partitions according to a schedule you define, and then stash them on some network resource that you identify via a UNC path. Usefully, Acronis runs in the background as a system service and if it finds a pre-existing backup file for the machine you've scheduled, it only adds a little daily changes file (commonly referred to as a "delta" or a "differential") to the set. With most PCs this file is of manageable size, and you're not supposed to ask how things are stored inside it - just have faith that, for example, your huge multigigabyte .PST file isn't entirely re-copied each day whenever you get an email, but is represented by a base block in the backup set plus a set of pointers to sectors containing successive differences.
So far, so good. My client had his nightly backup set to scoop up the whole of his machine's contents, which was terrific, until his high-performance striped set fell victim to an insidious leak in his water-cooling system. Savour that image for a while: it's as good as insurance claim excuses get. What happens to water-cooled PCs when they're moved around or knocked in the office environment is a topic for a whole other column, and what I'm focusing on here is the restore process. Acronis handles the restore problem by supplying a separate utility with the product, which lets you write a custom bootable CD for the express purpose of doing standalone backups and restores.
This is a pretty handy approach to take. Many competing products used to flounder around trying to create a bootable restore CD by "borrowing" your original installation discs and bodging a mixture of device drivers and bootable configurations, but Acronis' solution of a CD running a custom version of Linux, and loaded to the gunwales with device drivers, is becoming the predominant model these days. Pretty well every box on the planet - big-iron servers included - can be booted off this CD, then backed up (and restored) using it. This is because Acronis has assembled a huge collection of device drivers for every piece of hardware around, taking advantage of the broadly agreed standards for network file storage.
