Re: AZFS file system proposal

[Maxim Shchetynin]

On Tue, 17 Jun 2008 12:53:00 +0200
JÃrn Engel <joern@xxxxxxxxx> wrote:

> On Tue, 17 June 2008 11:35:10 +0200, Jan Engelhardt wrote:
> > On Tuesday 2008-06-17 11:06, Maxim Shchetynin wrote:
> > 
> > >I would say you can either mmap it or place a file system on it.
> > 
> > The help text implies that I *need* azfs to mmap it - and that sounds
> > like a Rube Goldberg machine.
> 
> Some people actually prefer filesystems over raw devices for a variety
> of reasons:
> - each file brings its own address space, which offers memory protection
>   from other processes,
> - files can have owners and permission bits,
> - files hide the fragmentation of the underlying device from users,
> - a file system provides a common and well-understood api for devices
>   with less common or well-understood apis,
> - etc.
> 
> Those reasons are as valid for azfs as for any other filesystem.  I have
> no doubt that azfs is useful.  It probably wouldn't hurt to express the
> merits of the filesystem and the problems it is supposed to solve a
> little better.  So far most criticism was based on the fact that noone
> understood what the hell it was all about.
> 
> My personal question when looking at this is: Why not use ext2?  It

Same reason we don't use ext2 for file system in RAM - we don't need any expensive caching and readahead mechanisms for devices which are as fast as main memory (or almost as fast).

> appears to me that an ext2 mounted with '-o xip' would solve the same
> problems.

-- 
Mit freundlichen GrÃÃen / met vriendelijke groeten / avec regards

    Maxim V. Shchetynin
    Linux Kernel Entwicklung
    IBM Deutschland Entwicklung GmbH
    Linux fÃr Cell, Abteilung 3250
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