Re: any way to disable fsync?

[Hans Reiser <reiser@namesys.com>]

Valdis.Kletnieks@vt.edu wrote:

>On Tue, 11 Jul 2006 17:04:56 PDT, Hans Reiser said:
>  
>
>>There are legitimate applications where the value of data is low enough
>>and the load is high enough, that losing the database upon crash is ok.
>>
>>I have mixed feelings about making it a mount option for reiser4 because
>>many users will not know what they do.  In the end though, I should just
>>sell the rope and advise but not control what people do with it.   If
>>someone writes it I will take a mount option patch to disable fsync iff
>>it comes with documentation that has a lot of warnings.
>>    
>>
>
>Two things to consider before writing code:
>
>1) Should it be done at the VFS level instead of in the filesystem?
>Architecturally, it might be better there, so it applies to ext3 and jfs
>and others too...
>
Yes, if the below is not done.

> 
>
>2) Alternatively, should it be done on a per-file basis (possibly
>flagged with a chattr or similar)? 
>
Once the pseudofiles interface or sys_reiser4() are debugged and
working, yes.

> It can't be done as an open()
>flag or ioctl(), because you're trying to override what the code does...
>That way, you can mitigate any fsync() load caused by one file, and
>still not leave yourself open to being screwed by some other application
>that tries to fsync() in other directories on that filesystem.  It
>would be Really Bad if /home/fred/db23.sqlite gets corrupted because
>the filesystem was mounted -nofsync because of /home/george/moby.sqlite
>overhead....
>  
>