Re: [HACKERS] RAW I/O device - Mailing list pgsql-hackers

From Karel Zak - Zakkr
Subject Re: [HACKERS] RAW I/O device
Date
Msg-id Pine.LNX.3.96.991207123103.2896C-100000@ara.zf.jcu.cz
Whole thread Raw
In response to Re: [HACKERS] RAW I/O device  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-hackers
On Mon, 6 Dec 1999, Bruce Momjian wrote:

> >  I raise the question, because the linux kernel opening with raw-device  
> > new way for a faster and better database engine. I know (and agree) 
> > that it not is priority for next year(s?). But it is interesting, and
> > is prabably good remember it during development, and not write (in future)
> > features which close this good way. 
> 
> I would be very surprised to see any significant change in raw vs.
> filesystem i/o on modern file systems, and I am sorry, but Linux ext2
> does not count as modern.

Yes. The ext2's limitation and unavailable is public secret and use it for
raw is crazy idea. On a raw device can be implement specific data organization
(specific for DB demand). Raw's advantage is non-universal organization.

A raw is not only about filesystem, this feature remove full control from 
OS kernel to DB (example data caching - kernel not has information 
how/why/what remove to cache but DB has this information... etc).
                    Karel     



  



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