Re: Guide(s?) to backup philosophies
- Date: Mon, 13 Mar 2017 10:12:31 -0400
- From: Dan Ritter <dsr@xxxxxxxxxxxxxxxx>
- Subject: Re: Guide(s?) to backup philosophies
On Sat, Mar 11, 2017 at 09:10:54AM -0600, Richard Owlett wrote:
> I have one partition that might be called a "production" environment, i.e.
> fairly stable and has the most valuable content.
> A second partition hosts my experiments - I've a project to create an
> optimal install. The third is the target of those experimental installs
> whose content doesn't rate explicit backups. The scripts for creating those
> installs being on the second partition.
> I've vague ideas of what backup pattern(s) I might follow.
> I'm looking for reading materials that might trigger "I hadn't thought of
> that" moments.
A quick overview:
Nobody wants backups. Everybody wants restores.
The questions are:
- what sort of disaster are you trying to recover from
- how often do you expect each to happen
- how much time are you willing to take recovering
- how much are you willing to spend
Let's take a few common scenarios.
First: a house full of personal use machines, plus a server. We
expect files to go missing or be accidentally deleted fairly
often, and we want it to be easy and cheap to recover from that.
The general answer for that is to store files on a networked
filesystem of some sort - NFS, SMB, sshfs, whatever - which
resides on the server and is snapshotted every so often. Tools
for snapshotting include LVM (not recommended), rsnapshot, and
btrfs and zfs. Anything with a user-accessible snapshot method
is good here - sysadmins don't need to be involved in every
Second: we have the same setup, but we would also like to make
it reasonably easy to restore a whole machine when we have an
accident with the hard disk.
For that, we need image backups over the network to the server.
We won't want to snapshot these, just keep the most recent good
image. Testing these every so often is necessary.
Third scenario: running a service that makes you money. For
this, we want to be up all the time. We can spend a lot more
money on this, because we expect to make money from it.
The solutions here involve high availability: multiple machines,
possibly in multiple locations, handling the same service in a
coordinated fashion. Users need to be automatically directed to
a working instance, and we need a monitoring system to tell us
when a machine is down, because if the HA system is working we
will not get user complaints.