Backups

[dsr-mzpnVDyJpH4k7aNtvndDlA at public.gmane.org (Dan Ritter)]

On Wed, Feb 11, 2009 at 08:49:47PM +0800, Samuel Baldwin wrote:
> 2009/2/11 Dan Ritter <dsr-mzpnVDyJpH4k7aNtvndDlA at public.gmane.org>:
> > How much do you think is a large amount? Tens of gigabytes? Tens
> > of terabytes?
> 
> Tens of gigabytes.

When you can buy a 1.5TB disk on the commercial market, tens of
gigs is not a large amount. 

> > How many machines are being backed up?
> 
> Just one, I believe. It's a fileserver for a bunch of other machines.
> And only one linux server.
> 
> > Do you want to restore the whole machine or just have the data
> > available?
> 
> For the "large" amounts, just have the data available. For the linux
> server, probably the whole machine.

Given this scale, I would buy three external 1TB disks and use
rsnapshot on all filesystems.

For a month, run rsnapshot nightly on disk 1. Unplug it at the
beginning of the workday.

For month 2, run rsnapshot nightly on disk 2. Unplug it at the
beginning of the workday.
Bring disk 1 home (or give it to an officer of the company to
take home).

For month 3, run rsnapshot nightly on disk 3. Unplug it at the
beginning of the workday.
Bring disk 1 back to the office. Put disk 2 offsite.

>From then on, each month you keep one disk active at night and
unplugged during the workday. The next most recent disk is
on-site but completely detached. The disk of last resort is
offsite.

> > What is your maximum allowable period between the primary
> > machine failing and your new machine being available?
> 
> Unknown as well.
> 
> > And how much is this all worth to you?
> 
> As little as possible, given the circumstances.

No, think about it this way: how much does it cost the company
per hour or day of unavailability? When does it stop being an
annoyance and start being an impediment? When will it affect
customers?

That's how much it's worth to you.

Also, it's not a backup system. It's a restore system. Nobody
cares about whether you did the backups -- they only care about
how much and how fast you can restore their data.

-dsr-

-- 
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