Hello, I agree to Matthew, here at croit we work a lot with containers all day long. No problem with that and enough knowledge to say for sure it's not about getting used to it. For us and our decisions here, Storage is the most valuable piece of IT equipment in a company. If you have problems with your storage, most likely you have a huge pain, costs, problems, downtime, whatever. Therefore, your storage solution must be damn simple, you switch it on, it has to work.
If you take a short look into Ceph documentation about how to deploy a cephadm cluster vs croit. We strongly believe it's much easier as we take away all the pain from OS up to Ceph while keeping it simple behind the scene. You still can always login to a node, kill a process, attach some strace or whatever you like as you know it from years of linux administration without any complexity layers like docker/podman/... It's just friction less. In the end, what do you need? A kernel, an initramfs, some systemd, a bit of libs and tooling, and the Ceph packages. In addition, we help lot's of Ceph users on a regular basis with their hand made setups, but we don't really wanna touch the cephadm ones, as they are often harder to debug. But of course we do it anyways :). To have a perfect storage, strip away anything unneccessary. Avoid any complexity, avoid anything that might affect your system. Keep it simply stupid. -- Martin Verges Managing director Mobile: +49 174 9335695 E-Mail: martin.ver...@croit.io Chat: https://t.me/MartinVerges croit GmbH, Freseniusstr. 31h, 81247 Munich CEO: Martin Verges - VAT-ID: DE310638492 Com. register: Amtsgericht Munich HRB 231263 Web: https://croit.io YouTube: https://goo.gl/PGE1Bx On Wed, 2 Jun 2021 at 11:38, Matthew Vernon <m...@sanger.ac.uk> wrote: > Hi, > > In the discussion after the Ceph Month talks yesterday, there was a bit > of chat about cephadm / containers / packages. IIRC, Sage observed that > a common reason in the recent user survey for not using cephadm was that > it only worked on containerised deployments. I think he then went on to > say that he hadn't heard any compelling reasons why not to use > containers, and suggested that resistance was essentially a user > education question[0]. > > I'd like to suggest, briefly, that: > > * containerised deployments are more complex to manage, and this is not > simply a matter of familiarity > * reducing the complexity of systems makes admins' lives easier > * the trade-off of the pros and cons of containers vs packages is not > obvious, and will depend on deployment needs > * Ceph users will benefit from both approaches being supported into the > future > > We make extensive use of containers at Sanger, particularly for > scientific workflows, and also for bundling some web apps (e.g. > Grafana). We've also looked at a number of container runtimes (Docker, > singularity, charliecloud). They do have advantages - it's easy to > distribute a complex userland in a way that will run on (almost) any > target distribution; rapid "cloud" deployment; some separation (via > namespaces) of network/users/processes. > > For what I think of as a 'boring' Ceph deploy (i.e. install on a set of > dedicated hardware and then run for a long time), I'm not sure any of > these benefits are particularly relevant and/or compelling - Ceph > upstream produce Ubuntu .debs and Canonical (via their Ubuntu Cloud > Archive) provide .debs of a couple of different Ceph releases per Ubuntu > LTS - meaning we can easily separate out OS upgrade from Ceph upgrade. > And upgrading the Ceph packages _doesn't_ restart the daemons[1], > meaning that we maintain control over restart order during an upgrade. > And while we might briefly install packages from a PPA or similar to > test a bugfix, we roll those (test-)cluster-wide, rather than trying to > run a mixed set of versions on a single cluster - and I understand this > single-version approach is best practice. > > Deployment via containers does bring complexity; some examples we've > found at Sanger (not all Ceph-related, which we run from packages): > > * you now have 2 process supervision points - dockerd and systemd > * docker updates (via distribution unattended-upgrades) have an > unfortunate habit of rudely restarting everything > * docker squats on a chunk of RFC 1918 space (and telling it not to can > be a bore), which coincides with our internal network... > * there is more friction if you need to look inside containers > (particularly if you have a lot running on a host and are trying to find > out what's going on) > * you typically need to be root to build docker containers (unlike > packages) > * we already have package deployment infrastructure (which we'll need > regardless of deployment choice) > > We also currently use systemd overrides to tweak some of the Ceph units > (e.g. to do some network sanity checks before bringing up an OSD), and > have some tools to pair OSD / journal / LVM / disk device up; I think > these would be more fiddly in a containerised deployment. I'd accept > that fixing these might just be a SMOP[2] on our part. > > Now none of this is show-stopping, and I am most definitely not saying > "don't ship containers". But I think there is added complexity to your > deployment from going the containers route, and that is not simply a > "learn how to use containers" learning curve. I do think it is > reasonable for an admin to want to reduce the complexity of what they're > dealing with - after all, much of my job is trying to automate or > simplify the management of complex systems! > > I can see from a software maintainer's point of view that just building > one container and shipping it everywhere is easier than building > packages for a number of different distributions (one of my other hats > is a Debian developer, and I have a bunch of machinery for doing this > sort of thing). But it would be a bit unfortunate if the general thrust > of "let's make Ceph easier to set up and manage" was somewhat derailed > with "you must use containers, even if they make your life harder". > > I'm not going to criticise anyone who decides to use a container-based > deployment (and I'm sure there are plenty of setups where it's an > obvious win), but if I were advising someone who wanted to set up and > use a 'boring' Ceph cluster for the medium term, I'd still advise on > using packages. I don't think this makes me a luddite :) > > Regards, and apologies for the wall of text, > > Matthew > > [0] I think that's a fair summary! > [1] This hasn't always been true... > [2] Simple (sic.) Matter of Programming > > > -- > The Wellcome Sanger Institute is operated by Genome Research > Limited, a charity registered in England with number 1021457 and a > company registered in England with number 2742969, whose registered > office is 215 Euston Road, London, NW1 2BE. > _______________________________________________ > ceph-users mailing list -- ceph-users@ceph.io > To unsubscribe send an email to ceph-users-le...@ceph.io > _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io
