[linux-lvm] Reserve space for specific thin logical volumes

[Eric Ren]

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.

I know all core developer are working for RedHat. But, I guess you 
experts will also be happy
to see any real contributions from other engineers. For me, some big 
issues in LVM I can see by now:

- 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).
- pvmove is slow. I know it's not fault of LVM. The time is almost spent 
in DM (the IO dispatch/copy).
- snapshot cannot be used in cluster environment. There is a usecase: 
user has a central backup system
   running on a node. They want to make snapshot and backup some LUNs 
attached to other nodes, on this
   backup system node.

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 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!".

[1] https://sourceware.org/lvm2/
[2] https://trello.com/

Regards,
Eric