From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Date: Wed, 13 Sep 2017 10:21:00 +0200 From: Gionatan Danti In-Reply-To: <9ba4086d-db8a-da37-9f65-a0eb055e089e@redhat.com> References: <418002318.647314.1505245480415.ref@mail.yahoo.com> <418002318.647314.1505245480415@mail.yahoo.com> <4dcfc4a557e98e0f98c6a1d568538d07@assyoma.it> <41419c78-953e-cb78-ade7-c9fc611a92fb@redhat.com> <9ba4086d-db8a-da37-9f65-a0eb055e089e@redhat.com> Message-ID: <4c9bdd9acc05d1dcc8d0bd1dc34a2fb2@assyoma.it> 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: Zdenek Kabelac Cc: LVM general discussion and development Il 13-09-2017 01:31 Zdenek Kabelac ha scritto: > It's not just about 'complexity' in frame work. > You would lose all the speed as well. > You would significantly raise-up memory requirement. > > There is very good reason complex tools like 'thin_ls' are kept in > user-space outside of kernel - with 'dm' we tend to have simpler > kernel logic > and complexity should stay in user-space. > > And of course - as pointed out - the size of your 'reserve' is so > vague :) and could potentially present major portion of you whole > thin-pool size without any extra benefit (as obviously any reserve > could be too small unless you 'reach' fully provisioned state :) > > i.e. example: > 10G thinLV with 1G chunks - single byte write may require full 1G > chunk... > so do you decide to keep 10 free chunks in reserves ?? What was missing (because I thought it was implicit) is that I expect snapshot to never change - ie: they are read-only. Anyway, I was not writing about "resevers" - rather, to preassign/preallocate the required space to a specific volume. A fallocate on a otherwise thinly provisioned volume, if you like. > Supposedly: > > lvmconfig --typeconfig full --withversion > > # Available since version 2.2.89. > thin_pool_autoextend_threshold=70 > > > However there were some bugs and fixes - and validation for not > allowing to create new thins - so do not try anything below 169 and if > you can > go with 173.... > Ah! I was not thinking about thin_pool_autoextend_threshold! I tried with 166 (for now) and I don't see any major problems. However, I will surely upgrade at the first opportunity! Thanks. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8