You are correct in you assumptions about it being different. It took me
a great deal of time to look over wht is in Linux before coming to these
conclusions.
Jeff
Gerard Roudier wrote:
>
> On Mon, 1 Nov 1999, Jeff V. Merkey wrote:
>
> > Pavel,
> >
> > The architecture of the RAID drivers is extremely primitive, and
> > limiting, and does not handle hotixing or distributed cases. There are
> > dependencies on NWFS for controlling th mirroring. At present, the
> > buffer cache does not support a logical semantic. It's true we could
> > "stand on our heads" and map something very unnatural to what's there,
> > but there are still issues and problems with the buffer cache and how it
> > acts. There are also config issues. NWFS style allows end users to
> > configure and use mirroring on Linux without needing a degree in
> > astro-physics to understand how to set it up.
> >
> > We basically need a smarter cache than what's there. Eventually, Linux
> > will evolve there (Since the page cache already resembles what's in NT).
>
> Your statements look a bit unclear to me.
>
> 1) You seem to state that NWFS is controlling mirroring from the FS. If
> true, this is different from the way Linux handles RAID.
>
> 2) On the other hand you claimed that handling some list of physical
> devices to mirror a logical device at buffer cache level (NT) is far
> superior than the way Linux handles RAID.
>
> I can understand that (1) perhaps allows to implement some features not
> possible with the layering used in Linux, at the price of increasing FS
> complexity probably.
>
> About point (2) I donnot see differences in essence, given your
> description of the way NT handle caching.
>
> I am always amazed by "logical .vs. physical" considerations that
> generally just mean that some layer or abstraction has been added
> somewhere, and nothing more.
> A single invention of the wheel has been enough for the real physical
> level, but this process seems to be recursive in information technology.
> ;-)
>
> Gérard.
>
> > Jeff
> >
> >
> > Pavel Machek wrote:
> > >
> > > Hi!
> > >
> > > > Which is exactly what we have concluded. We probably should provide
> > > > some input into 2.5 for our needs. We would be happy to put in the
> > > > subsystems we require. The benefit to Linux would be a built in fault
> > > > tolerant redirector within the cache (which is useful for this and
> > > > distributed support -- time to start thinking about this). This would
> > > > allow all of the Linux file systems to support multi-segmented
> > > > mirroring and fault tolerant failover without the RAID drivers.
> > >
> > > What is problem with the RAID drivers?
> > > Pavel
> > > --
> > > I'm really pavel@ucw.cz. Look at http://195.113.31.123/~pavel. Pavel
> > > Hi! I'm a .signature virus! Copy me into your ~/.signature, please!
> > >
> > > -
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