[Info-vax] Databases versus RMS

[Arne Vajhøj]

On 4/21/2012 12:44 PM, Paul Sture wrote:
> On Wed, 18 Apr 2012 08:40:50 -0500, Bob Koehler wrote:
>>     But I still find it a PITA to have to sprinkle fsynch calls all
>>     through my UNIX code when I want to decrease the buffering.
>
> You might enjoy these discussions where Linus Torvalds got upset over
> Ext3 and Ext4 behaviour:
>
> http://bit.ly/JcDKvX
>
> "if you write your metadata earlier (say, every 5 sec) and the real data
> later (say, every 30 sec), you're actually more likely to see corrupt
> files than if you try to write them together... This is why I absolutely
> detest the idiotic ext3 writeback behavior. It literally does everything
> the wrong way around -- writing data later than the metadata that points
> to it. Whoever came up with that solution was a moron. No ifs, buts, or
> maybes about it."
>
> And one comment I particularly like:
>
> http://bit.ly/JcDGMK
>
> --- start quote ---
>
> Difficult to have an ACID-compliant db when you don't have an ACID-
> compliant fs.
>
>
> I read Ted T'so's response pointed to by Charlie, above. This bit of
> reasoning has me laughing:
>
>> This sounds like a good thing, right? It is, except for badly written
>> applications that don’t use fsync() or fdatasync(). Application writers
>> had gotten lazy, because ext3 by default has a commit interval of 5
>> seconds, and and uses a ...
>
> Those damn application writers! The nerve of them to assume that the file
> system might actually store their data in reasonable time! What will they
> expect next? A database that stores data? An operating system that run
> the computer?
> /sarcasm

I believe that you can disable the writeback caching at mount time.

Arne