Re: mtime not updated in client cache?

[Peter Staubach <staubach@redhat.com>]

Roger Heflin wrote:

> 
>
>  
>
>>-----Original Message-----
>>From: nfs-admin@lists.sourceforge.net 
>>[mailto:nfs-admin@lists.sourceforge.net] On Behalf Of Peter Staubach
>>Sent: Friday, December 09, 2005 1:20 PM
>>To: Lever, Charles
>>Cc: nfs@lists.sourceforge.net
>>Subject: Re: [NFS] mtime not updated in client cache?
>>
>>Lever, Charles wrote:
>>
>>    
>>
>>>risks understood.
>>>
>>>however, how is this different from ext3?  a close() on an ext3 file 
>>>doesn't even attempt to schedule a flush of the data to 
>>>      
>>>
>>disk.  if the 
>>    
>>
>>>system crashes or the disk dies or the file system fills up, 
>>>      
>>>
>>the data 
>>    
>>
>>>is lost, just like in the NFS case.
>>> 
>>>
>>>      
>>>
>>I think that the difference is that a system crash also 
>>terminates the application and there is just more visibility 
>>into what happened.
>>    
>>
>
>On a local machine, the application can complete successfully, 
>and the data won't be written out for up to 30 seconds, and this
>can be higher on machines that have huge amounts of ram, and can
>hold a lot more in its write cache, so data can be
>lost even after the program completes properly if the machine crashes
>before the writes are finished.
>
>If you get a hard scsi/disk error when writing data from local cache, there
>is not a process to return that error to the program that generated
>the data assuming that the program is even still running.
>

Right.  But the difference is that these things are visible on the system.
The user can know that there may be a problem.  If such a thing happens on
the NFS server, without the client's knowledge, then there is no way of
telling why the data is not there, just that it is not.

    Thanx...

       ps


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