[Info-vax] OT: server farm backups

[johnwallace4 at yahoo.co.uk]

On Monday, 29 September 2014 15:02:14 UTC+1, Shadow  wrote:
> On 2014-09-29, CRNG <noemail at atthisdomain.gov> wrote:
> 
> > I retired about 15 years ago from being a system manager of a (then
> 
> > old) VAX/VMS system.  I did backups to a tape cartridge system daily,
> 
> > weekly, etc.
> 
> >
> 
> > I noticed a photo the other day of a modern server farm and got to
> 
> > wondering what in the world does a company like Amazon use to backup
> 
> > the gargantuan amount of data on their systems?  Surely it can't be
> 
> > something like tape cartridges.  Does anyone have any idea?
> 
> >
> 
> > Just curious about it.
> 
> 
> 
> I have no idea but I suspect they just replicate all their data with RAID
> 
> and replace disks that die and never really back anything up.
> 
> 
> 
> They leave that to the National Basketball Association and their 50 zillion
> 
> square mile colo in Utah.
> 
> 
> 
> --
> 
> NBA email. No signup required! We save all your emails, contacts, phone
> 
> calls, disk files and medical info forever. No bandwidth limitations and no
> 
> storage quotas!

[till a better answer comes along]

tldr: Repeat after me ten zillion times: RAID is not backup.

You may well be right that cloud vendors offer no guarantees
re backups (buyer beware) but RAID isn't backup anyway.

Put simply:

RAID makes it easier to survive hardware failures and still
have an accessible set of data.

RAID offers no resilience against finger trouble, application
misbehaviour, OS misbehaviour, and the like. In those cases
RAID just makes sure that your now-incorrect data is resilient
against (some) hardware failures.

A separate copy of your important data, perhaps a scheme 
involving multiple copies in some kind of suitable backup
routine, may give you the ability to restore data. But
unless you test the restore, you won't know for sure. It's
the restores that matter, not the backups.

Amazon used to have writeups on what you needed to do to
backup your data when using their cloud. Note carefully:
what YOU need to do to backup YOUR data. Maybe things have
changed.

Here endeth today's oversimplified lesson.