Re: Linux does not care for data integrity

[Jeff Garzik]

Bill Davidsen wrote:
> How about anything more? The truth is that much common hardware doesn't 
> really make the cache to disk move visible, and turning off cache really 
> hurts performance. And it would appear that fsync force a lot more data 
> out of memory than just the blocks for the file in question.

Correct.  That's the tradeoff with the ATA interface:  you must be aware 
of the cache flush requirements when designing a solution such as a 
database that really cares about fsync(2), or a journalling filesystem.


> However, the point I was making is that it would be useful to be able to 
> tell when the write to non-volatile took place, not to force that to 
> happen. Not to do anything which would flush a lot of other stuff and 
> busy the drive. What I suggest is NOT fsync, just a way to assure ordering.

To make that possible, POSIX must become a transactional, async I/O 
API... :)

	Jeff


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