Messages in this thread | | | Subject | Re: [linux-lvm] Re: [lvm-devel] [ANNOUNCE] LVM reimplementation ready for beta testing | From | "Steve Pratt" <> | Date | Thu, 31 Jan 2002 13:52:29 -0600 |
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Joe Thornber wrote: >On Wed, Jan 30, 2002 at 10:03:40PM +0000, Jim McDonald wrote: >> Also, does/where does this fit in with EVMS?
>EVMS differs from us in that they seem to be trying to move the whole >application into the kernel,
No, not really. We only put in the kernel the things that make sense to be in the kernel, discovery logic, ioctl support, I/O path. All configuration is handled in user space.
> whereas we've taken the opposite route >and stripped down the kernel side to just provide services.
Then why does snapshot.c in device mapper have a read_metadata function which populates the exception table from on disk metadata? Seems like you agree with us that having metadata knowledge in the kernel is a GOOD thing.
>This is fine, I think there's room for both projects. But it is worth >noting that EVMS could be changed to use device-mapper for it's low >level functionality. That way they could take advantage of the cool >work we're doing with snapshots and pvmove, and we could take >advantage of having more eyes on the core driver.
Since device_mapper does not support in kernel discovery, and EVMS relies on this, it would be very difficult to change EVMS to use device_mapper. Besides, EVMS already has all the capabilities provided by device mapper, including a complete LVM1 compatibility package.
>LVM2 may not seem that exciting initially, since the first release is >just concentrating on reproducing LVM1 functionality. But a lot of >the reason for this rewrite is to enable us to add in the new features >that we want (such as a transaction based disk format). It's on this >new feature list that we'll be mainly competing with EVMS.
Why compete, come on over and help us :-)
Steve
EVMS Development - http://www.sf.net/projects/evms Linux Technology Center - IBM Corporation (512) 838-9763 EMAIL: SLPratt@US.IBM.COM
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