OT: Backup Solutions

[Bill Campbell]

On Wed, Aug 26, 2009, Fairlight wrote:
>Confusious (Bill Campbell) say:
>> 
>> This works well amongst all *nix versions I have seen with the
>> caveat that there may be issues with older versions of OS X and
>> programs that use resource forks.  The Apple versions of rsync
>> handle these properly, but other *nix versions probably don't.
>
>I'm not so sure about that.  I've seen .zip archives with directory
>hierarchies that contained the OS/X data.  Notably, World of Warcraft
>addons often come with these files.  The forks sit in files in their own
>directories labelled for the OS.
>
>Rsync very well may work without issue to a mac, if regular zip does.

The issue is not rsync to a Mac, but rsync from a Mac to a
non-Mac or to another Mac using any rsync other than the one that
comes with the system which supports forks.

I read something yesterday that said that the new Snow Leopard
version of OS X drops support for the old Appletalk network
protocols.  Perhaps it finally gets entirely away from the
resource forks as well.  OS X has been gradually moving more
towards standard *nix file based administration and away from the
NeXt netinfo methods.

>The more interesting part to me regarding backups is achieving a quiescent
>state on the machine in a 24/7 environment where your backups are actually
>worth a damn.  By the time you get from point C to point F in a backup,
>there may be parts of C that are related to F that may be out of whack.

Of course this depends on the application and the level of
activity in the wee hours of the morning.  None of our clients
have 24/7 activity (other than ISPs where e-mail is continually
coming in and being read).  In most of these cases it's either
possible to shut down an application during the backup or one can
expect no activity to change the files.  It's also possible to
script things so that a rsync backup of general stuff is done,
which can take quite a while, then application specific backups
done, shutting down the application while rsync backs up its
data.

It seems to me that any truly busy, 24/7, mission critical
application should have application specific provisions for
redundancy and live replication to off-site systems.  One can't
shut down an airline reservation system to do a backup.

Sun's XFS file system has provisions to set snapshots of file
systems so one can backup the static snapshot, then merge in
changes after the backup is complete.  I think that Veritas
provides this type of functionallity as does AIX.

>Advice "back in the day" (1993-ish) used to be to only do your backups when
>the system was idle.  In this day and age, that's not actually practical in
>many installations.  You can use rsync, but unless you institute a
>maintenance period nightly where you essentially "nologin" the system -and-
>all the services and sub-services that can -write- data, you could be in
>for a world of hurt.  True, the more data you have, the better off you are.
>Better to have as much as you can get rather than less than you could have
>had.  But...it can still leave a lot to be desired.
>
>I'd love to see that part of the equation addressed in general.

I would guess that there's no general solution to this at the
Enterprise level, but that the methods differ for different
applications and database backends.  VMware is doing quite a bit
in this area for virtualizing machines, and I saw a presentation
by FalconStor, falconstor.com, who have virtualized NAS (Network
Attached Storage) allowing generallized access to different
vendor's NAS systems.

I have never looked seriously at NAS systems, but I think that
these generally have provisions for backups at the NAS level.
Netgear's ReadyNAS devices look interesting for the SMB market as
they provide a pretty good range of devices ranging from systems
that would work well in a small office to some fairly large boxes.

Bill
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