backup solutions for linux

jason andrade jason at dstc.edu.au
Fri Nov 8 08:04:38 CST 2002


On Fri, 8 Nov 2002, Colm MacCarthaigh wrote:

> but has the advantage that you can store backups off-site,
> and make copies easily. It's also a potentially infinite
> backup medium, dependent only on your number of tapes.

s/tapes/disks and you can replicate that.

> With tape it's easy to have incremental and full backups
> of your entire site going back years, and important

as above.

> consideration for old data. Also off-site backups mean
> if the place goes up in flames, you don't go out of
> business.

as above.  with offsite disk and a BCP.  which you also need
with a tape backup.

> Don't forget an important function of backups is protecting
> against admin mistakes, no matter when they were, it's
> not just for full recovery.

and user mistakes - admin mistakes can be more serious, but
there are a lot more users :-)

> You backup to disk ? You do realise that using raid0 accross
> 6 disks means that you've increased the mean-time between failure
> of that volume times 6.
>
> No offence, but that's possibly one of the stupidest, least
> sane backup schemas I've ever seen. At least make it RAID5
> to give yourself some hope.

i wouldn't be quite that harsh, but i would also have recommended
a RAID5 volume for the above reasons.  unless you are doing a
multi-multi level backup which is staging from production to
a raid0 array, which is then restaged to another, more protected
volume.


the thing is that with the modern size of disk volumes people are
forgetting that "backup" and "archival" are now quite becoming
quite different things with the mechanism for achieving this no
longer meeting the same expectations.

"backup" can now mean "i need to restore files, either partially
or totally, from user error or catastrophic disk failure, in the
shortest time possible"

"archive" or "archival backup" can now mean "we are required to be
able to bring back a file from X days/weeks/months/years ago for
our business/legal reasons, optionally in the shortest time possible
but i MUST be able to do it at all"


in the past both have been able to be combined into a single mechanism
of tape, which comfortably met both requirements.  this paradigm no
longer holds true for even medium sized installations anymore :-/.  as
admins we still have been taught "tape is good, backup to tape drive"
and we need to start looking outside this concept.


please don't get me wrong - i am a believer in using tapes, it is
just that the cost variables are not in the favour of tapes, even
given their other positive characteristics, for small/medium installations.

for large organizations, they already have the gold plated jacuzzis
so i guess the shiny tape drive solution isn't an issue..


regards,

-jason




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