Backup OS X Server with Retrospect

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Backup OS X Server with Retrospect

Andrea Govoni
Hi,
let's see if this list is still alive! :)

We are considering to backup an OS X Server with Retrospect using a
Windows machine with a lot of NTFS storage as the Retrospect server.
Does anyone have any experiences to share?
Of course we would use the latest versions of Retrospect, 9.5 for
Windows and 11.5 for Mac.

They say that OS X Server, including Mavericks, is fully supported but I
cannot find any specific information about how the unique needs of OS X
Server backups and restorations have been addressed.
Are all the OS X Services supported? Does the Retrospect client stop the
running service, backup the relevant database and restart the service?
If so, does it save the service state at each backup execution or does
it save only daily backups? How about full restorations?

Thanks in advance,


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Re: Backup OS X Server with Retrospect

The Mac OS X Server Mailing List mailing list

On 22 Sep 2014, at 1:26am, Andrea Govoni <[hidden email]> wrote:

> We are considering to backup an OS X Server with Retrospect [snip]

> They say that OS X Server, including Mavericks, is fully supported

Sorry, but I suspect this won't work correctly if a backup is taken while the server is running.  I'm going to go over the reasons which you understand (from your message) but some readers of this list won't.

While a service is running it keeps its state -- its configuration and latest data -- in two places: disk and memory.  If you backup just the stuff that's on disk, you will miss changes which haven't been written to disk yet: recent changes in configuration, and changes in data.  If you take a copy of just what's on disk you might get an old state (which would be okay, though not the best) but you also might get a state half way through changes (which might be inconsistent or scrambled and lead to later problems).

When you shut down the server you shut down all the services it's running.  When you do that it flushes all the stuff it's keeping internally to disk, because it won't have any memory when its shutdown.  It puts everything in a nice neat state suitable for use when it starts up again.

When you use Time Machine to back up an OS X Server computer, it sends a signal to each of its services just before they get backup: "Flush your changes to disk as if you're going to quit.".  (Or maybe it actually shuts them down as they're being backed up.  I don't know.)  This is special code written into Time Machine and it was introduced recently, which is why the first two versions of OS X which did Time Machine hosting had an explicit note in that Time Machine was not suitable for backing up a running OS X Server computer.

I don't know that the company behind Retrospect hasn't figured out how to do this properly, but I think if they had they'd be boasting about it more clearly.  My theory is that their text about backing up servers is about backing up a file server using access to the files its serving.  Which is fine and should work well.  But isn't anything like backing up a multi-service server by accessing its hard disk.  And what worries me is that they were talking about safe backup of OS X Sever when even Time Machine couldn't do it properly.

Simon

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Re: Backup OS X Server with Retrospect

The Mac OS X Server Mailing List mailing list
On 27/09/14 18:46, For administrators of Mac OS X Server and related
technologies wrote:
> Sorry, but I suspect this won't work correctly if a backup is taken while the server is running.

Thank you Simon for replying and sorry for this very late reply.
You were right, it turned out[1] that Retrospect doesn't stop services
and/or perform any special operation prior to backing up the files on
the disk.

> I'm going to go over the reasons which you understand (from your message) but some readers of this list won't.

It seems that this guy[2] should be educated as well… ;)


[1]
<http://forums.retrospect.com/index.php?/topic/151366-backup-os-x-server-with-retrospect/>
[2]
<http://forums.retrospect.com/index.php?/topic/151366-backup-os-x-server-with-retrospect/#entry258936>

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Re: Backup OS X Server with Retrospect

The Mac OS X Server Mailing List mailing list
> Thank you Simon for replying and sorry for this very late reply.
> You were right, it turned out[1] that Retrospect doesn't stop services and/or perform any special operation prior to backing up the files on the disk.


Thanks for the information. Good to know. Perhaps they will offer support for this in a future version? Good to know.

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