On Saturday 01 October 2016 12:39:58 Clive Menzies wrote:
Quick question. Are your backups incremental or complete every night?
This is probably better explained in the manpages. Amanda has the concept
of doing a full backup of everything in its disklist according to the
days you give it. Amanda will then shuffle the schedule such that those
full backups are done at random in that cycle, with an eye toward
equalizing, as much as possible, the amount of data saved during each
run. It does this by advanceing the the level 0's as it will not let a
given file go beyond that cycle before a full copy is made again.
Level 0 is a full copy of a file, level 1 is whats been changed in that
file since the last level 0. Level 2 is whats been changed since level
1, ad infinitum but most useage never gets past level 2. I have the
drive I use for amanda setup as 30 virtual tapes, using one a day, then
recycle. With 4 machines feeding amanda, that 1Tb drive stays at around
46% used:
gene@coyote:~$ df /amandatapes
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdc2 960798056 410555684 501429932 46% /amandatapes
I stayed on the devel branch of amanda, playing the part of the canary in
the coal mine for years while it was being heavily developed, but
apparently that grant ran out so not a lot has changed in around 5
years. So while I have a self made, slightly newer version on this
machine as master, v3.3.7p1, the slaves are all running 3.3.1 clients
from the wheezy repo. And it Just Works(TM).
I would be the first to point out that my way is NOT for archival storage
due to this 30 day and recycle setup. I could extend it to 60 days on
this drive I suppose, but this is not a business.
For a business, I would include the price of the drive as a CODB, fill it
up and put it on the shelf at a remote location so it doesn't all go up
in smoke when the place burns, thereby giving me the ability to recover
something 5+ years old, or for however long one has had that setup
running.
That $100 or less a month for a new commodity drive is far less of a CODB
than the archival storage of tapes would be over a 10 year period. And
you would have to add in that the tape drive(s) would be out of service
for about a month each annually while they spend the holidays in
Oklahoma City getting fresh heads and rubber at about a kilobuck each
for the rebuild. Thats been the track record here in my usage of tapes.
The hard drives all have been 10x (or) more dependable.
And all it takes is getting rid of the idea that one must do a full
backup on Friday nights. Yes, amanda can do that, but do it as a
separate configuration else you will drive the poor girl out of her mind
when she finds out all her carefully worked out plans have all gone
aglay.
And don't forget that in ones long term business plans, the technology
changes with time and there will come a time when you will have nothing
in the house that can read todays 1Tb sata hard drive. So having a
storage location to save the old tech that can read those drives should
be part of that long term plan also. And be damned hard headed about
it.