Build a Home Terabyte Backup System Using Linux
A terabyte-plus backup and storage system is now an affordable option for Linux users. This article discusses options for building and configuring an inexpensive, expandable, Linux-based backup server.
High-capacity disk drives are now widely available at prices that are incredibly cheap compared to those of only a few years ago. In addition, with so many Linux users now ripping CDs to disk, saving images from their digital cameras and recording video using digital camcorders and DVRs, such as MythTV, the need for backing up and archiving large amounts of data is becoming critical. Losing pictures and videos of your kids—or your audio music library—because of a disk crash would be a catastrophe. Fortunately, a high-capacity, Linux-based backup server can be built easily and cheaply using inexpensive disk drives and free software.
Virtually any home PC can meet the basic requirements for a backup server. If you have long backup windows or relatively small amounts of data, a slow computer is not an obstacle. Make sure your network is fast enough to transfer data within your backup window. For older equipment, the bottleneck for backups can be the disk data transfer bandwidth (30-150Mbps depending on disk technology).
Many consumer-level computers do not have cooling capacity for more than two internal hard disks. Most motherboards support a maximum of four onboard disks (often four ATA/IDE devices, but the two ATA/IDE and two SATA combination is becoming common). External USB high-capacity drives are also available. If your computer is older and has USB1, purchase an inexpensive USB2 PCI expansion card, which is ten times faster.
SCSI has fewer limitations, but it is expensive and has tended to lock purchasers in to “flavor-of-the-month” SCSI technologies. One option for disk expansion and upgrade is the Host Bus Adaptor (HBA), such as those made by Promise Technology. An HBA is a disk controller on a PCI expansion card. HBAs typically require no additional software, have their own BIOS and are not constrained by PC BIOS limits on disk size. HBAs let you put large disks (more than 120GB) into systems with legacy BIOSes, upgrade from ATA-33 to ATA-150 or mix ATA and SATA disks.
You may want to consider purchasing a dedicated fileserver. A bare-bones server capable of holding six disks (fully preassembled, no disks or OS) can cost less than $1,500 US. With this initial investment, you can expand disk space as needed for less than $0.80 per GB or grow by plugging in USB disks. Once you have decided how many disks you need, consider their space, cooling and noise requirements. Figure 1 shows an example of a backup system build from an old server. The system has well over a terabyte of storage capacity.
Even if you choose to build a server from scratch and populate it with high-capacity disks, you can expect costs for your terabyte-plus backup server still to be minimal in terms of its per-gigabyte price. This is because storage costs have decreased so dramatically. Table 1 provides a variety of different configurations for a backup server, along with estimated prices per gigabyte for each (note: prices are estimates and do not include taxes or shipping costs). As you can see from the table, costs for a new server equipped with more than two terabytes of storage can be built for a cost of less than $1.50 per gigabyte. That will back up a lot of home movies, digital pictures and music files!
Table 1. Some Backup Options, with Estimated per-GB Costs
|Type||Configuration||Capacity (TB)||Cost per GB ($)|
|ATA/SATA Disk||Internal disk||0.4||0.56|
|Linux Desktop*||Three internal disks||1.2||0.84|
|Linux Desktop*||Three internal disks plus two USB external||2.0||0.73|
|LaCie 2TB Storage||Network server appliance||2||1.15|
|Linux Server**||Six internal disks||2.4||1.21|
|Linux Server**||Six internal plus two USB external||3.2||1.08|
*Intel Celeron D 478 325 2.53GHz, 256MB of RAM. **Intel SC5275 chassis, Intel ATX Motherboard, dual-3GHz Xeon CPUs, 2GB of RAM.