I like to say that if you have 1 copy, you have none.  If 2, 1, if 3, you have 2 copies, the absolute minimum.  And try to decrease single points of failure, e.g. I use rsync for rsync.net and BackupPC to local disk, and tar to LTO tape after giving up on the opaque and baroque Bacula.<p><i>You need one offsite to prevent your house burns down and takes your machines and local backups.</i><p>I&#x27;m a long term fan of tape, from the first time I used UNIX(TM) in 1978 and a DECTape saved me when I was learning the power of the -rf flags to rm.<p>LTO tape systems for the home are not <i>insanely</i> expensive (then again, this is my minimum system today: <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10483361" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10483361</a> ECC is a requirement for me).  Street price for the HP LTO-4 internal SAS EH919SB I&#x27;m currently using is ~1,300 USD (and it wasn&#x27;t difficult to get it at around that price in 2011).<p>Add a LSI 2004 chip based SAS-2 controller such as the &quot;Avago&quot; LSI 9211-4i at $167 from Newegg right now to drive it, and a semi-disposable flash drive to feed it quickly so the tape doesn&#x27;t &quot;shoe shine&quot; (the tape moves very quickly, if you don&#x27;t feed it quickly enough it has to stop the tape and backup enough so that it&#x27;s at speed when it starts forward again and hits the location where it ran out).<p>I.e. at whatever speed write a 10GiB slice of your backup to the flash drive, then write that all at once to the tape.  Considering media costs, if you start from scratch today you&#x27;d probably be better off going LTO-5 now that LTO-6 is shipping, the media costs the same as for LTO-4 despite a near doubling of capacity.  I&#x27;ve got enough LTO-4 tapes that I&#x27;ll keep using them until my LTO-4 drive dies, then buy an LTO-5 drive, which per the standard can read two earlier generations, and write 1 earlier, and new LTO-5 media for it.<p>Current LTO-4 <i>and</i> LTO-5 tapes from HP or Fuji (I wouldn&#x27;t trust anyone else) go for $22-23, uncompressed capacities are 800 and 1.5 GB respectively.<p>And then store copies off-site, and copy your most important stuff at least once a day to a site like rsync.net, which saved me when a tornado trashed my apartment in 2011.