[linux-cifs-client] Corrupted data on write to Windows 2003 Server

Danny Sung dsung at lantronix.com
Mon Dec 11 21:10:06 GMT 2006


Thanks so much!  That solved the problem.  Curiously, I also seem to get 
better performance!  7 MB/sec rather than 5 MB/s.  Perhaps I should run 
the test again... it's possible the system was loaded with backups the 
first time.


Shirish S Pargaonkar wrote:
> linux-cifs-client-bounces+shirishp=us.ibm.com at lists.samba.org wrote on 
> 12/08/2006 01:24:24 PM:
> 
>  > When copying a file from linux to windows, I noticed corrupted data
>  > whenever my data size is larger than about 100-200MB.  I ran a few
>  > tests, using 'dd', writing a 1GB file with varying block sizes (1, 10,
>  > 50, 100, and 200 megs).   Each one reported a different md5 when reading
>  > back.  Only the 200 MB block size was successful, but it may have been a
>  > fluke... I need to run the test a few more times.
>  >
>  > The actual number of bytes in the destination file is correct.  But
>  > running 'cmp' afterwards, I discovered that the destination ends up
>  > being 0 padded after a certain point.  The exact spot seems to wander,
>  > but it appears to be around the 800-900MB mark for these files.
>  >
>  > I don't get any error messages or anything from the actual 'dd' command.
>  >   The only message I get is a kernel message saying: "CIFS VFS: No
>  > writable handles for inode", which I suppose explains it all.  But it'd
>  > be nice if the user commands reported some sort of failure.
>  >
>  > I don't suppose there are any mount options I can give to cifs to make
>  > it do more checking or retries or anything?  Or how do I actually
>  > prevent the "no writable handles" problem?
>  >
>  > Of course, if I use rsync, that seems to get around the problem.  But it
>  > seems kind dumb to have to do that for mounted filesystems. =P
>  >
>  >
>  >
>  > Linux system: Fedora Core 5
>  > Linux aeolus.eng.lantronix.com 2.6.18-1.2200.fc5smp #1 SMP Sat Oct 14
>  > 17:15:35 EDT 2006 i686 i686 i386 GNU/Linux
>  >
>  >
>  > Windows System: Windows Server 2003 R2 Standard w/ SP1
>  >
>  > mount options:  cifs (rw,mand)
>  >
>  > I don't think this uses samba since cifs is a kernel module, but just in
>  > case, my samba version is: 3.0.23c
>  >
>  > Thanks for any assistance,
>  > Danny
>  >
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> 
> Danny,
> 
> We have seen this problem and are working on it.  Sizes of the source 
> and destination files are same but
> md5sum would report different values.  I have seen this problem with 
> large files like 500MB+.
> I have seen some (page) ranges in destination file filled with NUL bytes.
> But we have observed this problem only with copying files to Windows 
> server and not with Samba server.
> 
> As a work-around, you may want to use option forcedirectio during mounts.
> 
> Regards,
> 
> Shirish S. Pargaonkar
> 



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