[Gllug] re: qmail file-system syncing

[Peter Childs]

itsbruce at uklinux.net wrote:

>On Mon, Nov 10, 2003 at 05:50:30PM +0000, Richard Cohen wrote:
>  
>
>>On Mon, 10 Nov 2003 itsbruce at uklinux.net wrote:
>>
>>    
>>
>>>On Mon, Nov 10, 2003 at 05:35:01PM +0000, Richard Cottrill wrote:
>>>      
>>>
>>>>That said, synchronizing the whole filesystem does seem a bit of a
>>>>kludge at first blush.
>>>>        
>>>>
>>>Syncing the filesystem simply means flushing any cached writes for the
>>>filesystem.  There's no such thing as syncing *part* of the filesystem
>>>(unless you are using "filesystem" to mean "everything under /", as
>>>opposed to the individual mounted filesystems).
>>>      
>>>
>>Really?
>>
>>What's fsync then?
>>    
>>
>
>On Linux, fsync doesn't do a proper job (not according to the POSIX
>spec, anyway).  To achieve a consistent filesystem using fsync on Linux
>you would have to check all the inode's filenames and then fsync all the
>containing directories.  But yes, you're right, you can use fsync to
>sync specific files to disk, if you tread carefully.
>
>  
>
If the discussion on the postgres mailing list is anything to go by 
fsync on an ide disk is a waste of time anyway. ide apparently lies. 
General surgestion is to use SCSI if it matters.

Peter Childs


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