# Service/Stack host to host migration **URL:** \ **Category:** Rancher 1.x\ **Created:** [May 21, 2017, 8:16am UTC](https://forums.suse.com/t/service-stack-host-to-host-migration/6424 "2017-05-21T08:16:01Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![EugenMayer](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/eugenmayer/32/1415_2.png) [@EugenMayer](https://forums.suse.com/u/EugenMayer)\ **Post date:** [May 21, 2017, 8:16am UTC](https://forums.suse.com/t/service-stack-host-to-host-migration/6424/1 "2017-05-21T08:16:01Z")
**TLTR Question: How to deal with stateful services host migration and the question about the volumes** Moving from proxmox KVM based service runtimes to rancher docker based stacks, i currently search for a solution/strategy to be able to migrate a service(stack) from one host to another. I did make up my mind for this for months already, i am running rancher/rancheros for more then a year now with different purposes, but now i move our core infrastructure - and this one has frequent service movement ( maintanance, server capacity /load ) Obviously the core issue for migrating the stacks/services are the volumes - i do yet not really strive for hot migrations. **As far as i understand, there are 2 main primary strategies (correct me):** 1. Complete Shared storage: ClusterFS alikes sync a whole block device / partition across all hosts, replicating and duplicating anything, anytime and making all volumes accessible on all hosts at any given time. Pros: make horizontal scaling with stateful apps even easier, since the whole storage is shared anyway ( across hosts) Cons: Data duplication ( space ) and probably general network load ( a bit ) 2. On Demand Volume migration, so if i tell rancher to move a service from host A to B, the volumes get copied “automatically” on demand Pros: no dupes, network traffic on demand only Cons: no horrizontal scaling of stateful apps out of the box * * * Solutions: _For strategy 1:_ - Convoy + NFS - [Portworx](https://docs.portworx.com/) (Block device based syncing) - Longhorn ( soon ) _For strategy 2:_ AFAICS nothing as close to be automated, so like as a side-task when rancher migrates a service to a host it cares about the volumes. So doing it manually as "elegant as possible" a) [docker checkpoints](https://docs.docker.com/engine/reference/commandline/checkpoint/) probably using [CRUI](https://criu.org/Main_Page) - somewhat [like this article describes](https://circleci.com/blog/checkpoint-and-restore-docker-container-with-criu/) b) [Docker base volume backups](https://docs.docker.com/engine/tutorials/dockervolumes/#backup-restore-or-migrate-data-volumes) a) is yet not really done and b) is horrible manually craftig, you cannot do this at scale at all. It works, i have done that already, but the process is way to time consuming and partially error prone. **So finally, my question is:** What are you guys using, suggesting or looking for? What is the general idea of the rancher developers / team about this topic? Maybe i missed it, but i do not see a lot of channeled discussions about that yet. i) Is the only option to run a clusterFS like storage - no matter how big data becomes ( which is a pain point here )? ii) Do i have the wrong POV on infrastructure right now, do i try to stuff the old idea on how services are run and located over a more cloud based, agile one. Saying that, i am using to run a stack ( KVM based linux host plus App + its DB + whatever ) on one host ( KVM ) - and if its more performance / host ist going to be maintained, i move the whole KVM somewhere else. With rancher / docker based stacks, one could argue, that database and app can be separated and be on different hosts and are scale\>1 and any given time. Beside the extra resources consumed due to 2+ and the extra complexity for HA with databases and app, that might work, but is probably not a solution for every single stack in mind - for some this is just way over the top iii) are any solutions there / planned for strategy 2 yet? iiii) how do you guys handle “storage” with portworx - do you just add a second drive to the rancheros and then and this to the service as the “synced one” - and thats it? So every volume created on that “storage driver” is shared? Is there a way to migrate from on storage driver to another? If yes, this could be used as a transition/transfer layer for on-demand volume migration. So local-storage HOST A-\>portworx dervice HOST A-\>portworx dervice HOST B-\>local-storage HOST-B + delete on portwox ( move ) Sorry for this really long post, but i though i try to start a more general, wide discussion about storage, since i think this could be a question being interested for a broader audience. ---
**Author:** ![EugenMayer](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/eugenmayer/32/1415_2.png) [@EugenMayer](https://forums.suse.com/u/EugenMayer)\ **Post date:** [May 26, 2017, 7:24am UTC](https://forums.suse.com/t/service-stack-host-to-host-migration/6424/2 "2017-05-26T07:24:22Z")
Any chance to have some insight probably by the Rancher-Team to share their mission on this?