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From: Jack Benny on 1 Dec 2009 08:28
We are using a commercial product that use VDI for backing up our
databases across a network to another server. We have one relatively
large data base (3.7 TB) that, when we back it, ends up taking about
16 hours. We have other databases, not quite that big, that don't
take anywhere near that long. (3.5 hours to back up 2.5 TB). I have
observed that when the backup first starts it appears to move right
along. It'll do 100GB the first hour, then 70GB the next hour and
then it gradually and inexorably slows down to 20 or less GB per hour.

Does anybody have any idea why this might be happening?

Could it have something to do with VDI?

Any suggestions on what to monitor while the backup is running that
might give a clue as to why it starts so fast in the beginning and
then just slowly strangles to a crawl?

All DB servers are 2005 9.0.3042,.

We've put this question out to our vendor and as yet we have no
response from them.
From: Andrew J. Kelly on 1 Dec 2009 10:03
I hope this is a compressed backup right? If not I would look at another
vendor pretty quick. I doubt this has anything to do with SQL Server itself
or the VDI interface and more to do with the vendors app.

--

Andrew J. Kelly SQL MVP
Solid Quality Mentors

"Jack Benny" <pkline_no_spam(a)ltdcommodities.com> wrote in message
news:gb5ah5dhrabu035j6h1g1ic630h0rkuhda(a)4ax.com...
> We are using a commercial product that use VDI for backing up our
> databases across a network to another server. We have one relatively
> large data base (3.7 TB) that, when we back it, ends up taking about
> 16 hours. We have other databases, not quite that big, that don't
> take anywhere near that long. (3.5 hours to back up 2.5 TB). I have
> observed that when the backup first starts it appears to move right
> along. It'll do 100GB the first hour, then 70GB the next hour and
> then it gradually and inexorably slows down to 20 or less GB per hour.
>
> Does anybody have any idea why this might be happening?
>
> Could it have something to do with VDI?
>
> Any suggestions on what to monitor while the backup is running that
> might give a clue as to why it starts so fast in the beginning and
> then just slowly strangles to a crawl?
>
> All DB servers are 2005 9.0.3042,.
>
> We've put this question out to our vendor and as yet we have no
> response from them.

From: Jack Benny on 1 Dec 2009 13:46
On Tue, 1 Dec 2009 10:03:05 -0500, "Andrew J. Kelly"
<sqlmvpnooospam(a)shadhawk.com> wrote:

>I hope this is a compressed backup right? If not I would look at another
>vendor pretty quick. I doubt this has anything to do with SQL Server itself
>or the VDI interface and more to do with the vendors app.

This is defintiely compressed. The end result if the 3.7 TB is a
little over 500GB.
If it is the vendors app I'd love to know that. I just don't know
what to measure or monitor while it's running to eliminate everything
else.

�When you eliminate the impossible, whatever remains--however
improbable--must be the truth.� --Sir Arthur Conan Doyle
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