[Dirvish] Offsite Disks

Brian P. Martin Brian at MartinConsulting.com
Thu Aug 23 17:12:01 UTC 2007


> I've actually been backing up all my data currently to my Linux box,
> that has one hard drive with all my images. I've been giving some
> thought to complimenting this with offsite disks but I'm debating on
> the
> exact procedure on how to do this. 

I take the easy way out and just run dirvish twice.  I have two banks
defined (one on an installed disk and one on a local disk).  Each has a
vault for each machine in question with different names (i.e. "svr3" and
"svr3-offsite"), but the default.conf files in each pair point to the same
machine.  This is inefficient, but it was easy and quick and meets my needs.
It does has some small advantages over cloning one copy to another:

1) If a file is busy during one back-up, it might be available when the
second one runs
2) If the first back-up gets written badly (bad spot on disk or other
anomaly), the second one will probably still be OK since it's not just a
copy of the first.

People with longer retention periods may want to consider rotating the
offsite disks significantly faster than the images expire.  For example, I
commonly rotate disks weekly but have a retention period of a month or more.
In this way, offsite disk #1 has back-ups from weeks 1 and 3, and disk #2
has back-ups from weeks 2 and 4.  This way, if I have to reach for an
offsite disk and it turns out to be defective, I can still to the other
offsite disk and have something more current than if I rotated them monthly.
I do this because if a file doesn't change often, Dirvish may only have one
copy of it on a disk.  If a media failure occurs in that file, all of the
back-ups of it on the disk are lost.  By rotating frequently, I keep two
relatively recent copies of everything.

          -Brian Martin





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