On 2017-02-01 17:48, Duncan wrote:
Adam Borowski posted on Wed, 01 Feb 2017 12:55:30 +0100 as excerpted:
On Wed, Feb 01, 2017 at 05:23:16AM +0000, Duncan wrote:
Hans Deragon posted on Tue, 31 Jan 2017 21:51:22 -0500 as excerpted:
But the current scenario makes it difficult for me to put redundancy
back into service! How much time did I waited until I find the
mailing list, subscribe to it, post my email and get an answer?
Wouldn't it be better if the user could actually add the disk at
anytime, mostly ASAP?
And to fix this, I have to learn how to patch and compile the kernel.
I have not done this since the beginning of the century. More
delays,
more risk added to the system (what if I compile the kernel with the
wrong parameters?).
The patch fixing the problem and making return from degraded not the
one-
shot thing it tends to be now will eventually be merged
Not anything like the one I posted to this thread -- this one merely
removes a check that can't handle this particular (common) case of an
otherwise healthy RAID that lost one device then was mounted degraded
twice. We need instead a better check, one that sees whether every
block group is present.
This can be done quite easily, as as far as I know, the list of block
group is at that moment fully present in memory, but someone actually
has to code that, and I for one don't know btrfs internals (yet?).
I didn't mention it because you spared me the trouble with your hack-
patch that did the current job, but FWIW, there's actually a patch that
does per-chunk testing as you indicate, but it got merged into a longer
running feature-add project (hot-spares, IIRC), and thus isn't likely to
be mainline-merged until that project is merged.
But who knows when that might be? Could be years before it is considered
ready.
Meanwhile, perhaps it's simply because I'm not a dev and am not
appreciating the complexities of some detail or other, but as
demonstrated by the people who have local-merged that patch to get out of
just this sort of jam, as well as the continuing saga of more and more
people appearing here with the same problem, it could be an arguably high
priority fix on its own, and should have been reviewed and ultimately
mainline-merged on its own merits, instead of being stuck in someone's
feature-add project queue for potentially years, while more and more
people who could have definitely used it have to either suffer without it
or go and find and local-merge it themselves. Even if this feature is
critical to the longer term feature, merge of this little one now would
make the final patch set for the longer term feature that much smaller.
Agreed, it should have been mainlined. I have no issue with the
hot-spare patches depending on it, but it's a severe bug.
But that's a btrfs-using sysadmin's viewpoint, not a developer viewpoint,
and it's the developer's doing the work, so they get to define when and
how it gets merged, and us non-devs must either simply live with it, or
if the circumstances allow, fund some dev to have our specific interests
as their priority and take care of it for us.
I don't care in this case if I draw some flak from the developers, but
this particular developer viewpoint is wrong. If this was a commercial
software product, the person responsible would at least be facing some
serious reprimand, and depending on the company, possibly would be out
of a job. This is a severe bug that makes a not all that uncommon
(albeit bad) use case fail completely. The fix had no dependencies
itself and
Meanwhile, perhaps I should have bookmarked that patch at least as it
appeared on-list, but I didn't, so while I know it exists, I too would
have to go looking to actually find it, should I end up needing it. In
my defense, I /thought/ the immediate benefit was obvious enough that it
would be mainline-merged by now, not hoovered-up into some long-term
project with no real hint as to /when/ it might be merged. Oh, well...
I think (although I'm not sure about it) that this:
http://www.spinics.net/lists/linux-btrfs/msg47283.html
is the first posting of the patch series.
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