Dne 11.9.2017 v 17:31 Eric Ren napsal(a):
Hi Zdenek,
On 09/11/2017 09:11 PM, Zdenek Kabelac wrote:
[..snip...]
So don't expect lvm2 team will be solving this - there are more prio work....
Sorry for interrupting your discussion. But, I just cannot help to ask:
It's not the first time I see "there are more prio work". So I'm wondering:
can upstream
consider to have these high priority works available on homepage [1] or trello
tool [1]?
I really hope upstream can do so. Thus,
1. Users can expect what changes will likely happen for lvm.
2. It helps developer reach agreements on what problems/features should be on
high
priority and avoid overlap efforts.
lvm2 is using upstream community BZ located here:
https://bugzilla.redhat.com/enter_bug.cgi?product=LVM%20and%20device-mapper
You can check RHBZ easily for all lvm2 bZ
(mixes RHEL/Fedora/Upstream)
We usually want to have upstream BZ being linked with Community BZ,
but sometimes it's driven through other channel - not ideal - but still easily
search-able.
- lvmetad slows down activation much if there are a lot of PVs on system (say
256 PVs, it takes >10s to pvscan
in my testing).
It's should be opposite case - unless something regressed recently...
Easiest is to write out lvm2 test suite some test.
And eventually bisect which commit broke it...
- pvmove is slow. I know it's not fault of LVM. The time is almost spent in DM
(the IO dispatch/copy).
Yeah - this is more or less design issue inside kernel - there are
some workarounds - but since primary motivation was not to overload
system - it's been left a sleep a bit - since focus gained 'raid' target
and these pvmove fixes are working with old dm mirror target...
(i.e. try to use bigger region_size for mirror in lvm.conf (over 512K)
and evaluate performance - there is something wrong - but core mirror
developer is busy with raid features ATM....
- snapshot cannot be used in cluster environment. There is a usecase: user has
a central backup system
Well, snapshot CANNOT work in cluster.
What you can do is to split snapshot and attach it different volume,
but exclusive assess is simply required - there is no synchronization of
changes like with cmirrord for old mirror....
If our upstream have a place to put and discuss what the prio works are, I
think it will encourage me to do
more contributions - because I'm not 100% sure if it's a real issue and if
You are always welcome to open Community BZ (instead of trello/github/.... )
Provide justification, present patches.
Of course I cannot hide :) RH has some sort of influence which bugs are more
important then the others...
it's a work that upstream hopes
to see, every engineer wants their work to be accepted by upstream :) I can
try to go forward to do meaningful
work (research, testing...) as far as I can, if you experts can confirm that
"that's a real problem. Go ahead!".
We do our best....
Regards
Zdenek
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