On Tue, Apr 15, 2014 at 11:57:51AM -0700, Russell Johnson wrote: > Which is where the question, “Have you tested your backup?” was born. > Hard drives fail. This is a fact of life.
I host http://dirvish.org on my server, though I haven't contributed much lately. Dirvish is one of many backup solutions. Dirvish works OK with my "hoard all backups forever, hard drives are inexpensive" approach to sysadmin. With 3TB Seagate USB3 external drives going for $100, and a year's worth of nightly hardlinked images fitting on one, this is cheap. Backups aren't just for saving files, but for keeping a time history of my systems, useful for diagnosing the origin of problems. For example, Real Soon Now, I will be combing through the last few months of nightly backups looking for where Network Manager changed, and why it no longer restarts wifi after a suspend. Then I will diff the files and executables, and download sources if necessary, and learn Who Screwed Up (probably me) and How To Unscrew Things. Anything you don't have two copies of, you eventually have zero copies of. Too many copies, organized and somewhat searchable, is better than none. "sum /backup/dirvish/root/*/tree/bin/foo" may take a while ( * = hundreds of images ), but it tells me the day foo changed. Automated update logs tell more. Note that two drives on one power supply is not really two copies. If Mr. Power Supply loses an output capacitor and decides to send unregulated 24 volts out the 12V wires to your drives, they will all smoke together. Not all drive failures are due to the drives themselves. That is one advantage of externals, and why RAID is often an oxymoron. Another advantage is that you can take the external drives offline with a mechanical christmas tree timer, so that even if the Bad Guys take control of your backup server, your backups themselves are inaccessable most of the time. If you don't like USB3, you can also get "drive toasters" that connect by eSATA and use bare drives. When I restore from backup, I rebuild drives in the toaster. In addition to the files dirvish saves, I also save the first megabyte of /dev/sda , so I can easily restore grub and partition tables to the toaster drive. Keith -- Keith Lofstrom [email protected] _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
