Windows Delayed write error when backing up to network share

I'm running SQLServer2000 SP4 on two separate servers. The problem I'm 
running into is that when I schedule a database backup either through 
Maintenance Plans or manually through Enterprise Manager the backup fails 
with the error:
 "Windows-Delayed Write Error. Windows was unable to save all the data for 
the file \Device\LanmanRedirector\<unc path>. The data has been lost. This 
error may be caused by a failure of your computer hardware or network 
connection. Please try to save this file elsewhere". 

I'm backing up to a NAS and using a UNC path to get there. I can copy a file 
of the same size through explorer with no problem, it's only when SQL tries 
to backup to the network that the error comes up.

In researching this, I've found several articles pointing to various causes. 
What I've checked so far includes turning off the write cache setting for the 
drives in Device Manager|Disks and changing the registry entry 
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Lanmanworkstation\Parameters\enablesecuritysignature 
from 1 to 0 to shut off SMB signing. Nothing has resolved the issue as yet.

This problem us also accompanied by System event log error MrxSmb 50 and 
several MSSQLServer errors in the application log that all point to write 
errors on the destination drive or losing connection with the destination, 
but the network connection is fine.

Any ideas would be appreciated.

TIA
Ken

Not recommended backing up to a network drive or share.

can you backup locally and then copy the file up ?

This is what I had to do at a previous job in Orlando.


Greg Jackson
Portland, OR 

I need to be able to backup to a network device as the local disks that are 
of enough size are clustered and inaccessible to anything except the active 
node. Backing up to a network share cuts the entire time it takes to restore 
from tape out of the loop. This is critical for DR purposes. 

Besides the issue isn't whether it's recommended, but what is causing the 
problem.

Hi

In good hardware, with good available bandwidth, I have never had any
problems.
As an exercise, copy a big (10Gb+) file over the network from your server to
the destination server. Use Explorer or XCOPY. See it this works. now try
copying 2 versions of the file at the same time to the destination. If both
are successful, you should not have a problem.

Networks are un-reliable.

If it is so critical to DR, any reason you are running in a configuration
that is not fully supported?

Have a look at
 http://www.**--****.com/ ;en-us;304261 to see what
MS thinks how you need to do it.

Regards
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Zurich, Switzerland

IM:  XXXX@XXXXX.COM 

MVP Program:  http://www.**--****.com/ 

Blog:  http://www.**--****.com/ 





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