Backing up a VM - is it dangerous ?

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Backing up a VM - is it dangerous ?

4D Tech mailing list
Hi

One of my sites contracts out their server maintenance, procurement and general support to an IT contractor. The contractor is fairly adaptable and I have good professional relations with them, however I still have to work within certain “overall parameters”.

One of these is that their 5-user 4D accounts server runs on a VM (Virtual Machine). When I asked them about an external drive to hold the 4D backups, they replied “don’t worry, the whole VM gets backed up once per day and the backup is held on external drives”.

What are the implications of backing up the VM while 4D server is still running ? On the old days this would have been a complete no-no because of un-flushed caches, locked datafiles and all sorts of issues. Is anybody running this particular configuration ?

Though I hopefully won’t be visiting the dentist anytime soon, Laurence Olivier's words to Dustin Hoffman spring to mind…..”is it safe !?”  ;)

regards

Peter
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RE: Backing up a VM - is it dangerous ?

4D Tech mailing list
It will work, but it is *not* safe.

I would use a 4D backup anyway on the same drive the vm works. In this case they save with the snapshot of the vm the 4D backup files too.
Or you have to dive into the feature of volume shadow copies and the supporting of them by 4D.

Regards
Lutz


> -----Original Message-----
> From: 4D_Tech [mailto:[hidden email]] On Behalf Of Peter Jakobsson
> via 4D_Tech
> Subject: Backing up a VM - is it dangerous ?
>
> Hi
>
> One of my sites contracts out their server maintenance, procurement and general
> support to an IT contractor. The contractor is fairly adaptable and I have good
> professional relations with them, however I still have to work within certain “overall
> parameters”.
>
> One of these is that their 5-user 4D accounts server runs on a VM (Virtual Machine).
> When I asked them about an external drive to hold the 4D backups, they replied “don’t
> worry, the whole VM gets backed up once per day and the backup is held on external
> drives”.
>
> What are the implications of backing up the VM while 4D server is still running ? On the
> old days this would have been a complete no-no because of un-flushed caches, locked
> datafiles and all sorts of issues. Is anybody running this particular configuration ?
>
> Though I hopefully won’t be visiting the dentist anytime soon, Laurence Olivier's words
> to Dustin Hoffman spring to mind…..”is it safe !?”  ;)
>
> regards
>
> Peter

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Re: Backing up a VM - is it dangerous ?

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In reply to this post by 4D Tech mailing list
Peter,
In a low transaction environment it's probably not an issue. But if the
copy happens to take place during a cache flush you can wind up with a
corrupted datafile. It's easily fixed by MSC but a record or two may be
lost. I've experienced this myself by making a copy of a live datafile on a
system with maybe 10 users logged in at the moment. It works most of
the time but fails a non-trivial number of times.

I would try to convey to the vendor that the architecture of 4D is not one
that lends itself to this type of backup.

If they won't give you an external drive the backup and log file is the
final word. Client's risk, client's choice.

On Mon, Nov 5, 2018 at 3:17 AM Peter Jakobsson via 4D_Tech <
[hidden email]> wrote:

> What are the implications of backing up the VM while 4D server is still
> running ? On the old days this would have been a complete no-no because of
> un-flushed caches, locked datafiles and all sorts of issues. Is anybody
> running this particular configuration ?
>

--
Kirk Brooks
San Francisco, CA
=======================

*We go vote - they go home*
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Re: Backing up a VM - is it dangerous ?

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In reply to this post by 4D Tech mailing list
Definitely not safe prior to v17.  With v17 there's support for Volume Shadow Copy which puts the datafile in a safe state prior to VMWare taking a snapshot.


--
Jeffrey Kain
[hidden email]




> On Nov 5, 2018, at 6:17 AM, Peter Jakobsson via 4D_Tech <[hidden email]> wrote:
>
> Though I hopefully won’t be visiting the dentist anytime soon, Laurence Olivier's words to Dustin Hoffman spring to mind…..”is it safe !?”  ;)

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Re: Backing up a VM - is it dangerous ?

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Many thanks for the useful replies.

I’ve contacted the IT contractor to try to negotiate a new backup strategy.

Hopefully it will be less of a sweat than the China trade talks :-)

Peter

> On 5 Nov 2018, at 13:36, Jeffrey Kain via 4D_Tech <[hidden email]> wrote:
>
> Definitely not safe prior to v17.

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Re: Backing up a VM - is it dangerous ?

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On Nov 5, 2018, at 2:00 PM, Peter Jakobsson wrote:

> Many thanks for the useful replies.
>
> I’ve contacted the IT contractor to try to negotiate a new backup strategy.
>
> Hopefully it will be less of a sweat than the China trade talks :-)

Peter,

If you just enable 4D Backup you should be find as long as you have an idea when IT is doing the backup of your 4D Server machine.

As you know, 4D Backup will make a guaranteed good copy of your live, running 4D Server data file. So when IT does a backup of the machine they will backup the 4D Backup file. Only issue is if at the exact time 4D Backup is running they run the backup the copy of the backup file may corrupted. But if you know when they are doing the backup, just schedule 4D Backup to not run near that time.

I had been doing this with one of my clients for many years. They are running a VM that 4D Server runs on. IT told me they are doing a snapshot every night on that machine at 3am. So I just set 4D Backup to run at 2am. Been working great.

Now that client has moved to v17 and I’ve got Volume Shadow Support running on 4D Server. So any snapshots they do will now guarantee the data file is valid if the snapshot is restored. Still running 4D Backup, but now IT thinks 4D is a real, first class VM citizen since it has VSS.

Tim

*****************************************
Tim Nevels
Innovative Solutions
785-749-3444
[hidden email]
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