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Really slow DFS replication

Posted on 2013-05-15
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Last Modified: 2013-06-03
Hi

I have two Server 2008 servers connected via a VPN.

I have DFSR setup to replicate one folder.

The replication seems to be extremely slow, so much so that its not catching up with itself so is constantly out of date.

I have already tried resetting it all up and it seemed to start replicating ok bt then slowed again.

I have noticed that on the 2nd server the size of the DFSR private folder in system volume information is large (17GB) but im not sure if i should worry about it.

Thanks in advance.

Tim
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Question by:timb551
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LVL 23

Expert Comment

by:Nagendra Pratap Singh
ID: 39170308
how fast is your VPN?

If it is VPN, it can be slow.
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LVL 76

Expert Comment

by:arnold
ID: 39170372
Use oocla's mini (speedtest.net) after you test the available bandwidth at each location.

Set it up on each server and then test the transfer speed via the VPN.

DFS-R has a bandwidth setting, depending on what else is going through the VPN, you may have other higher priority traffic going through the VPN.
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LVL 23

Expert Comment

by:Nagendra Pratap Singh
ID: 39170431
In a simple VPN you have 4 speeds.

Point A download
Point A upload
Point B download
Point B upload

Your VPN will work at the slowest speed of the above.  Often there would be some numbers but it is the CIR that is guaranteed by your ISP.
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Author Comment

by:timb551
ID: 39170616
The lines at each site are

Site A (Main Site): 17MB down, 1.5MB up
Site B (DR Site): 200MB down, 200MB up

I have run DFSR on slower networks than this and been ok.

DFSR is set to do unlimited on the bandwidth settings.

Whats the best way to test the speed between the two servers?
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LVL 76

Expert Comment

by:arnold
ID: 39170959
Ookla's mini from speedtest.net

It uses flash based testing.  Once unzipped, in IIS use the asp, aspx.

From Main site to DR the 1.5MBs is the limit on the speed, you should make sure that differential compression is selected.
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Author Comment

by:timb551
ID: 39170990
Differential compression is set.  I will try the mini software now
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Author Comment

by:timb551
ID: 39171087
Site A download from Site B : 9MB
Site B download from Site A : 1MB

That seems to make sense.
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LVL 76

Expert Comment

by:arnold
ID: 39171722
Your replication flow is from site A to site B.  Main site sees most of the changes and pushes it to DR. (Upstream bandwidth is the limit on replication)
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Author Comment

by:timb551
ID: 39171730
That's correct.
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LVL 76

Expert Comment

by:arnold
ID: 39171914
How large are the hourly changes?
What files do you have are these documents or are these larger CAD type files, where each file can be in the >100MB file?
Presumably the DFS does not include backup files.

Increasing the connection at sitea is the only possible solution given reducing the daily file addition/change is impractical.
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Author Comment

by:timb551
ID: 39171953
There is 1 x 300mb file daily and the rest are just word excel etc. Nothing major.

But at the moment its so far behind it could be approx. 50gb behind.

Should I get a full copy of site a copied directly to site b so that its up to date and then see what happens?
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LVL 76

Assisted Solution

by:arnold
arnold earned 500 total points
ID: 39172383
300MB should take abou 2/3 hours to replicate by itself if it was the only data stream.
Des this file have to replicate?

Try the following, exclude the larger file from replication by adding its extention to the do not replicate rule.
Then see whether the other files that are created changed can maintain synchronization by themselves.

What else is accessing the DR?
Double check your DFS setting to make sure users primarily access the local DFS share and not trying to use the VM bandwidth to the DR.

Is the DR bandwidth metered manning you pay extra for consumed bandwidth?
Consideration trying to use the DR DFS as primary in Oder to see whether there will be mouser impact in terms of slower access to files, and then whether the b to a replication can be synchronized in a more timely fashion.


Just to make sure dFS replication is not really a backup plan.  A mistaken deletion one side will replicate to the other.
One should have a backup of the data.
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Author Comment

by:timb551
ID: 39174088
Thanks Arnold.

How do you force the users to only use the local dfs share?

The dr bandwidth is unlimited and un capped.

The DR is part of a multi backup system so no worries there.

I will make the other changes you mentioned and see if it helps.
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Accepted Solution

by:
arnold earned 500 total points
ID: 39174868
within the DFS share's properties/topologies you can control what type of DSF distribution to use, round robin, etc.  You can designate one target as preferred versus the other.
DFS management.  navigate to the name space and get properties. There is a referral tab.
Which Option do you have selected?

Alternatively, once you look at the namespace servers, select one and properties, there is an advanced tab and a referral override where you can select the DR to be first.

See if that alters/affects the synchronization.

You may need to manually get them closer to synchronized.
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