Re: Proposed Enhancements to MD

Kevin P. Fleming
2004-01-13T18:20:00Z

Matt Domsch wrote:

> DDF is quickly becoming important to RAID and system vendors, and I
> welcome Adaptec's work to implement DDF support on Linux.

Fully agreed, the days of vendor-specific metadata formats need to be
numbered (with a small number). Speaking a customer with a CMD
FC-to-SCSI RAID controller, which used to be dual-redundant but is now
single (because of a dead unit), we are not looking forward to the day
when the remaining controller dies and we lose all the data on the array
due to a forced metadata format change.

However, given that this will not likely be 2.6 material until after
it's built and tested in 2.7 and then backported, it doesn't seem to
make any sense to me to build any of this on top of the MD subsystem at
all (see other replies about using DM instead). Additionally, it also
does not seem to make any sense to build any of the DDF
reading/writing/management in the kernel _at all_. There is no advantage
to it being there once initramfs is a standard part of the boot process,
so all of this should be done is userspace and just communicated into
the kernel to tell it what logical devices to construct using which DM
modules.