Offsite backup for Linux using hard disk drive dock and SATA laptop disks

Many years ago, I wrote about why tapes are still the most efficient backup method. I also wrote about using tape backup on Linux for a home network.

That was then, when all the server's data fit in on 10 GB tape cartridge. Since then, digital cameras have gotten more pixels, with individual pictures jumping from 350 KB, to 950 KM, and then to 2 MB. Cameras acquired video, first VGA resolution, and now High Definition 720p. All this means that the data is growing exponentially.

Current tape technology have suffered from many issues for small business and home networks:

• Capacity: the current tape capacity has not kept up with the ever increasing size of disks and the growth of data on them.
• Availability: It is not easy to find the cartridges at a good price. Too often they are special order at shops.
• Cost: The tape drives are expensive, several hundred dollars to a few thousand. The cartridges can also be expensive.

For example, DLT tape drives are $825 at NCIX ($773 at Amazon Canada). This is for only 160GB native capacity. The cartridge for it is $52 (at NCIX).

And 160GB is not a lot. My current server backup is approaching 100GB, and such a drive will only last a couple of years at that rate. That does not justify the investment in an expensive tape.

LTO tapes offer higher capacities, e.g. 400GB or 800GB native, but at a higher cost for drives, and limited availability for media.

For example, an 800GB cartridge LTO 4 is $50 NCIX, which is reasonable. But the drive is a whopping $2,252 at NCIX, and has a Serial Attached SCSI (SAS) interface, meaning it will not fit in servers used in homes or small business.

Therefore, for all the above reasons, I was on a quest to find another way to backup a home network.

Of course, using Ubuntu Linux backup and a USB enclosure with the dump utility has proven to be successful, once you find a stable USB disk (e.g. LaCIE 1TB disk). Also see: setting up a hard disk USB 2.0 enclosure for backup under Linux.

All the above work well, except for two issues:

• USB tends to be slow, and spike the CPU usage. Since backups run in the wee hours of the morning, this is not a big deal. And whether the backup takes 30 minutes or 90 minutes is not a big issue.
• Lack of offsite capability: the powered USB disks are clumsy to transport around, and bulky too.

So, the solution lied in the Vantec NexStar hard drive dock NST-100SU, costing only $32.99, with SATA laptop 2.5" disk drives (Seagate, 500GB at a cost of $69.99).

This dock has both USB and eSATA connections. They provide an eSATA bracket and 6 ft SATA cable as well. I was hoping to use SATA because it is faster than USB. However, I was unable to get the disk to be hotpluggable. The server did not see the disk when connected with SATA unless it was plugged in when the server booted. Perhaps this was because the server did not have the port multiplier feature for SATA. I am not sure.

The server is running Ubuntu Server Edition 8.04 LTS, so it has a 2.6 Linux kernel.

If you are reading this, and found a solution to making eSATA work, please post a comment below.

Once I connected the dock using USB, it worked well though.

To mount a disk, plug it in the dock, power up the dock, wait for about 10 seconds, and then issue the command:

mount /dev/sdc1 /backup/1

Then do the dump backup as described above.

When you want to take the disk out, you do the following:

umount /dev/sdc1

Then power off the dock, and eject the disk.

You can now remove a disk once a week, and take it to your work, or give to a friend for safe keeping. This takes care of the offsite backup part.

Every week, get back the other disk, and send the latest one offsite.