Open Stack

On Wed, Feb 3, 2016 at 6:32 AM, Sam Yaple <samuel at yaple.net> wrote:

> [snip]
>
Full backups are costly in terms of IO, storage, bandwidth and time. A full
> backup being required in a backup plan is a big problem for backups when we
> talk about volumes that are terabytes large.
>

As an incidental note...

You have to collect full backups, periodically. To do otherwise
assumes *absolutely
no failures* anywhere in the entire software/hardware stack -- ever -- and
no failures in storage over time. (Which collectively is a tad optimistic,
at scale.) Whether due to a rare software bug, a marginal piece of
hardware, or a stray cosmic ray - an occasional bad block will slip through.

More exactly, you need some means of doing occasional full end-to-end
verification of stored backups. Periodic full backups are one
safeguard. How you go about performing full verification, and how often is
a subject for design and optimization. This is where things get a *bit*
more complex. :)

Or you just accept a higher error rate. (How high depends on the
implementation.)

And "Yes", multi-terabyte volumes *are* a challenge.
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