Wednesday, March 7, 2012

Backups causing connectivity issues

I'm maintaining a database with an automated backup process.

Periodically, it does a "BACKUP DATABASE" to a local file and then do a file copy across the network to another system. This file is 2.7GB and when it is being copied it causes network problems; specifically ADO connections to the database get broken.

Does anyone have experience with this kind of issue?A DOS Copy is causing a network problem?

I wouldn't think so.

Where's the code, and what's the specific error message.|||A DOS Copy is causing a network problem?

I wouldn't think so.

Where's the code, and what's the specific error message.

I have a C++ ADO client application that gets:

Database COM exception.
HRESULT = -2147467259 (0x80004005)
[DBNETLIB][ConnectionRead (recv()).]General network error. Check your network documentation.

This client application is running 24/7 on many different workstations. They all encounter this error and shutdown at the same time. It seems to only encounters this error during the file copy operation I mentioned. I assume that the 2.7GB file copy consumes so much bandwidth that it disrupts other network activity. CPU use on the server is low. I wouldn't have guessed this as the problem but that is certainly what the symptoms suggest.|||I still wouldn't put any money down on that...

But as check, why not copy the file over during periods of low activity...|||I still wouldn't put any money down on that...

But as check, why not copy the file over during periods of low activity...

We do. We copy it over at midnight. The C++ client app I mentioned needs to run 24/7/365 though and it can't lose network connectivity to the database (this is all on a LAN and has UPS).|||OK...out of the box thinking...is there anything else affected?

You sure it's not something to do with the way the app is constructed?

I'm no network guy, but can you put a sniffer on the network?|||DOS copy may be the same as Windows copy. As I understand things, Windows copy eats a lot of bandwidth in parity checks, and whatnot. Can you use FTP to deliver the database to an FTP server? That may be a lighter connection.|||Thanks guys. Those suggestions might work but the network guys agreed to just backup to a separate local hard drive. That will definitely spare the network.|||For files of these sizes to move over LAN people usually set up a dedicated NIC on a different subnet. If you spare a couple of bucks wisely (SQLLiteSpeed) you may shrink the size of the backup file down to around 500MB.

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