Input/output errors on file accesses with Fedora Core 2

[Jeff Vian]

On Wed, 2004-06-30 at 06:25, David Robson wrote:
> Hi
> 
> I have two applications that simultaneously analyse a large (~750Mb) file.
> One application does a "tail -f" on the file.   The other does a "cat"
> 
> When they are both running, after a few seconds, the "cat" process fails
> with the following error
> 
> cat: <NAME OF MY FILE>: Input/output error
> 
> The file is on a NFS mounted server, but the problem occurs no matter
> how I do the mounts.  I have tried udp, tcp, increasing the number of 
> transmissions
> and changing the buffer sizes.  I am not sure if NFS is an issue.  I 
> have tried copying
> the file to a local disk, but then the "cat" is so quick, there isn't 
> enought time for
> the error to occur.
> 
> I am using the 2.6.6-1.435 kernel; the problem occurs for the SMP and the
> uniprocessor flavours.  I am running Fedora Core 2.  The applications work
> fine on RedHat 9
> 
> Has anyone seen this before, of have any ideas?
> 

"cat" starts at the beginning of the file and reads to the end.

"tail" reads a number of lines at the end of the file, and with the -f
option keeps the file open for reading as something appends to the end
of the file.

It sounds to me like you are seeing conflict between the two readers and
cat is failing since the file is actually open for reading by tail.

I tested the scenario you present on my box and did not get any errors.

The only difference is that I am not using nfs here.