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SubjectRe: (reiserfs) Re: LVM / Filesystems / High availability

how about the following division of responsibility.

needs to know how to grow/shrink on command in the device it is on

presents a single device to the filesystem and handles the details of
allocating/dealocating sections of lower level devices (similar to the md append
mode, but dynamicly adjustable)

raid drivers/low level drivers
handles the raid specifics (striping, etc) and physical device access.

This sort of seperation would keep the raid details out of the LVM (where they
are not needed if you have a hardware raid system) and lets the filesystem work
on stuff as if it is all on one device (for the cases where the LVM puts
todeather chunks from several devices)

David Lang

On Tue, 30 Jun 1998, Shawn Leas wrote:

> Date: Tue, 30 Jun 1998 16:28:35 -0500 (CDT)
> From: Shawn Leas <>
> To: "Theodore Y. Ts'o" <tytso@MIT.EDU>
> Cc: "Craig I. Hagan" <>,
> Heinz Mauelshagen <>,
> Subject: Re: (reiserfs) Re: LVM / Filesystems / High availability
> On Tue, 30 Jun 1998, Theodore Y. Ts'o wrote:
> > From: "Craig I. Hagan" <>
> > Date: 30 Jun 1998 13:10:43 -0400
> >
> > let me propose the following to you: i have a very large (read > 100g)
> > raid array (hitachi). when i carve a chunk out for a specific system,
> > it looks like one honkin huge spindle. i DON'T want to allocate/deallocate
> > based upon entire spindles.
> >
> > OK, great. You have a RAID unit. Is it RAID 0/1/4/5? Presumably the
> > RAID unit is doing the striping, et. al, right? In this configuration,
> > how often do you need to resize the amount of disk space allocated for a
> > particular filesystem, and in what size chunks? Is it usually only to
> > grow the filesystem, or are you sometimes shrinking it? (And in what
> > units do you typically do the growing and shrinking --- and why?)
> You speak like there's a significant performance hit with the LVM! With
> the benifit of being able to tune your device and implement striping,
> mirroring, etc... The performance gain of having all that with NO IMPACT
> to the complexity of an FS is more than a justification for it.
> Your not spliting up the disk device, per say, you're only handling
> address remapping in 4 meg units. You can choose bigger, or smaller. I
> don't see you complaining about disk blocks...
> -Shawn
> > If you don't mind the questions, I'd like to better understand your
> > application, and what's driving your requirements. Thanks....
> >
> > - Ted
> >
> -
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