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Do Automated Cross-Platform Network Backups The Easy Way, Part 2
June 27, 2006
In Part 1 we discussed all manner of fascinating backup tools and strategies. Today we roll up our sleeves and build a sleek, dependable cross-platform network backup server with the excellent BackupPC. We're not going to mess around with dumb old tape drives, nor CDs, nor DVDs, nor floppy diskettes, but nice, fast high-capacity hard drives.
Your backup server should be robust, and not some tired old classic Pentium recycled from a moldy basement. It needs at least an 800 megahertz processor, 256 megabytes of RAM, and enough disk space. A three-disk SATA RAID 5 array, managed with EVMS (Enterprise Volume Management System) is great for a small shop. With EVMS you can painlessly scale up as you need.
Networks with a small number of users might consider using RAID1 (mirroring), with the second drive in a removable bay for offsite storage. Rotate at least two removable drives for easy redundancy.
Unison or rsync are good programs for performing offsite network backups of your backup server. Yes, that's a whole lot of backing up. Ever since we abandoned good old reliable paper for digital media, it's just layers upon layers.
Fierce battles are waged over which is better, software or hardware RAID. Forget the cheapie built-in RAID that comes on a lot of motherboards these days, or the inexpensive PCI-IDE RAID cards for under $30--those are junky and nowhere near as good as Linux RAID. Good-quality hardware controllers cost $150- $600, and are operating-system independent. The best ones have onboard CPUs and RAM, do SATA hot-swap and hot spare, and support as many as eight disks. Linux software RAID is more flexible, as it works at the block level instead of whole disks, so you can use individual partitions in your array. It does not support hot-swap, but it does support hot spares.
The most important components are the power supply and cooling. All those drives suck up a lot of power and throw off a lot of heat. Wattage alone does not tell the tale; power supplies must deliver multiple different voltages. SATA drives need 12V. A good power supply delivers a steady, clean 12V to multiple drives; bad ones can't. Big roomy cases with nice big 120mm case fans are cooler and quieter than small crammed cases.
Modern CPUs and RAM are also significant energy users, sucking up small voltage but big wattages. (See Resources for a comparison table.)