[CentOS] Re: Linux backup help

Warren Young warren at etr-usa.com
Sat Nov 15 01:43:58 UTC 2008


Amos Shapira wrote:
> Assuming I take the approach you suggest and have to restore the cache
> (with the tested versions) after it's lost in a disaster, is there a
> way to do that (short of backing it up)? 

I don't see why this is a big deal.

First off, even way out at the end of a RHEL/CentOS release's lifetime, 
the full set of patched packages will be just a few gigs of data.  (It 
almost *has* to be smaller than a single-layer DVD...the patch set can't 
practically be bigger than the original OS it's patching.)  Today, a 
couple of gigs costs nearly nothing to store, and 3 years from now when 
the last CentOS 5 patches come out, storage and bandwidth costs will be 
1/4 what they are now.

Second, this scheme replicates the cache to multiple machines.  Most of 
the time, only a single machine will get killed at a time, so you can 
get the cache copy from one of its neighbors.  If you're worried about a 
disaster that can take out a whole building's worth of machines at once, 
surely the cost of a few gigs of professional off-site storage isn't out 
of the question?

I keep the most precious 4 GB of my home data backed up on Amazon S3. 
This costs me about 75 cents a month.  The solution I'm proposing would 
take maybe half that out at the end of its useful life, and more like 
1/10 that today.  Total cost over three years is maybe the cost of lunch 
for you and a few friends.  You'll spend more than that of your 
company's time writing the script to pull the data from a public 
repository, and on top of that it's a waste of someone else's bandwidth 
to treat them as your company's backup system.

> move around entire cache backups across continents.

Continents??  What, now we're worried about protecting against total 
continental destruction?  Maybe you're thinking you'll need those 
backups to help reboot civilization on another continent?

Sheesh, talk about overengineering...  I would have thought that sending 
backups to another time zone would be more than sufficient.


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