Neil Brown wrote:
On Saturday February 10, davidsen@xxxxxxx wrote:
Iustin Pop wrote:
On Sat, Jan 27, 2007 at 02:59:48AM +0100, Iustin Pop wrote:
From: Iustin Pop <iusty@xxxxxxxxx>
This patch exposes the uuid and the degraded status of an assembled
array through sysfs.
[...]
Sorry to ask, this was my first patch and I'm not sure what is the
procedure to get it considered for merging... I was under the impression
that just sending it to this list is enough. What do I have to do?
Normally I would expect Neil to pick it up and forward it, but I would
have expected an ack from him. He's been busy with other problems, NFS
as I recall, and may have missed it, so I cc'd him this time.
Neil, I would think this is 2.6.21 material unless you see a problem I
missed.
yeh - sorry about that. mail is somewhat of a lossy protocol for me.
I usually try to reply, but sometimes it just doesn't happen.
Resending after a suitable pause (1-2 weeks) is never a bad idea.
Exposing the 'degraded' status is probably a good idea. I'll take
that.
Exposing the UUID isn't - and if it were it should be in
"md_default_attrs" rather than "md_redundancy_attrs".
I don't think moving it would get much argument, but having it visible
has advantages as noted in the original post, and opens the door to
someone writing code to allow the uuid to be changed with a write to a
sys file. We had a discussion of setting uuid a few months ago, I think
you agreed it was a reasonable thing to do.
The UUID isn't an intrinsic aspect of the array. It is simply part of
the metadata that is used to match up different devices from the same
array.
I plan to add support for the 'DDF' metadata format (an 'industry
standard') and that will be managed entirely in user-space. The
kernel won't know the uuid at all.
Outside of forcing changes for all of us using uuid, what does this
standard compliance buy us as users? Or you as a maintainer? Does this
let Linux get run on a million computers which can't now because of lack
or standard compliance? I'm always worried when things change without a
visible benefit, so feel free to make the benefits visible. Managed in
user space is not a big item for me, it means there will be more more
places for errors to creep in.
So any solution for easy access to uuids should be done in user-space.
Maybe mdadm could create a link
/dev/md/by-uuid/xxxxxxxx -> /dev/whatever.
??
Which would be kept in sync how when the uuid is changed?
I'm not trying to argue with you, just trying to cover the benefits and
possible exposures from the change.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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