From mboxrd@z Thu Jan 1 00:00:00 1970 References: <76b114ca-404b-d7e5-8f59-26336acaadcf@assyoma.it> <0c6c96790329aec2e75505eaf544bade@assyoma.it> <8fee43a1-dd57-f0a5-c9de-8bf74f16afb0@gmail.com> <7d0d218c420d7c687d1a17342da5ca00@xenhideout.nl> <6e9535b6-218c-3f66-2048-88e1fcd21329@redhat.com> <2cea88d3e483b3db671cc8dd446d66d0@xenhideout.nl> From: Zdenek Kabelac Message-ID: Date: Mon, 11 Sep 2017 17:52:31 +0200 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] Reserve space for specific thin logical volumes Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Eric Ren Cc: LVM general discussion and development 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