Hi all, I have been chasing answers for this for months on the Proxmox forums, Reddit, and the LevelOneTechs forums and haven’t gotten much guidance, unfortunately. Hoping Lemmy will be the magic solution!
Perhaps I couched my initial thread in too much detail, so after some digging I got to more focused questions for my follow-up (effectively what this thread is), but I still didn’t get much of a response!
In all this time, I even have one more random thought I haven’t asked elsewhere - if I “Add Storage” of my ZFS pools in Proxmox, even though the categories don’t really fit data storage (the categories are like VM data, CT data, ISOs, snippets, etc.), then I could attach these to a VM or CT and replicate them via “normal” Proxmox cluster replication - is it OK to add such data pools to this storage section as such?
Anyway, to the main course - the summary of what I’m seeking help on is below.
Long story short:
- 3 nodes in a cluster, using ZFS.
- CTs and VMs are replicated across nodes via GUI.
- I want to replicate data in ZFS pools (which my CTs and VMs use - CTs through bind-mounts, VMs through NFS shares) to the other nodes.
- Currently using Sanoid/Syncoid to make this happen from one node to two others via cronjob.
So three questions:
- If I do Sanoid/Syncoid on all three nodes (to each other) - is this stupid, and will it fail - or will each node recognize snapshots for a ZFS pool and incrementally update if needed (even if the snapshot was made on/by a different node)?
- As a sub-question to this - and kind of the point of my overall thread and the previous one - is this even a sensible way to approach this, or is there a better way?
- For the GUI-based replication tasks, since I have CTs replicating to other systems, if I unchecked “skip replication” for the bind-mounted ZFS pools - would this accomplish the same thing? Or would it fail outright? I seem to remember needing to check this for some reason.
- Is this PVE-zsync suitable for my situation? I see mention of no recursive syncing, which I don’t fully know what that means, and I don’t know if that’s a dealbreaker. I suppose if this is the correct choice - then I need to delete my current GUI-based CT/VM replication tasks?
For those with immense patience, here was the original thread with more detail:
Hi all, so I setup three Proxmox servers (two identical, one “analogous”) - and the basics about the setup are as follows:
- VMs and CTs are replicated every 15 minutes from one node to the other two.
- One CT runs Cockpit for SMB shares - bind-mounted to the ZFS pools with the datasets that are SMB-shared.
- I use this for accessing folders via GUI over the network from my PC.
- One CT runs an NFS server (no special GUI, only CLI) - bind-mounted to the ZFS pools with the datasets that are NFS-shared (same as SMB-shared ones).
- Apps that need to tap into data use NFS shares (such as Jellyfin, Immich, Frigate) provided by this CT.
- Two VMs are of Debian, running Docker for my apps.
- VMs and CTs are all stored on 2x2TB M.2 NVMe SSDs.
- Data is stored in folders (per the NFS/SMB shares) on a 4x8TB ZFS pool with specific datasets like Media, Documents, etc. and a 1x4TB SSD ZFS “pool” for Frigate camera footage storage.
Due to having hardware passed-through to the VMs (GPU and Google Coral TPU) and using hardware resource mappings (one node as an Nvidia RTX A2000, two have Nvidia RTX 3050s - can have them all with the same mapped resource node ID to pass-through without issue despite being different GPUs), I don’t have instant HA failover.
Additionally, as I am using ZFS with data on all three separate nodes, I understand that I have a “gap” window in the event of HA where the data on one of the other nodes may not be all the way up-to-date if a failover occurs before a replication.
So after all the above - this brings me to my question - what is the best way to replicate data that is not a VM or a CT, but raw data stored on those ZFS pools for the SMB/NFS shares - from one node to another?
I have been using Sanoid/Syncoid installed on one node itself, with cronjobs. I’m sure I’m not using it perfectly (boy did I have a “fun” time with the config files), and I did have a headache with retention and getting rid of ZFS snapshots in a timely manner to not fill up the drives needlessly - but it seems to be working.
I just setup the third node (the “analogous” one in specs) which I want to be the active “primary” node and need to copy data over from the other current primary node - I just want to do it intelligently, and then have this node, in its new primary node role, take over the replication of data to the other two nodes.
Would so very, very badly appreciate guidance from those more informed/experienced than me on such topics.
I think you’re asking too much from ZFS. Ceph, Gluster, or some other form of cluster native filesystem (GFS, OCFS, Lustre, etc) would handle all of the replication/writes atomically in the background instead of having replication run as a post processor on top of an existing storage solution.
You specifically mention a gap window - that gap window is not a bug, it’s a feature of using a replication timer, even if it’s based on an atomic snapshot. The only way to get around that gap is to use different tech. In this case, all of those above options have the ability to replicate data whenever the VM/CT makes a file I/O - and the workload won’t get a write acknowledgement until the replication has completed successfully. As far as the workload is concerned, the write just takes a few extra milliseconds compared to pure local storage (which many workloads don’t actually care about)
I’ve personally been working on a project to convert my lab from ESXi vSAN to PVE+Ceph, and conversions like that (even a simpler one like PVE+ZFS to PVE+Ceph would require the target disk to be wiped at some point in the process.
You could try temporarily storing your data on an external hard drive via USB, or if you can get your workloads into a quiet state or maintenance window, you could use the replication you already have and rebuild the disk (but not the PVE OS itself) one node at a time, and restore/migrate the workload to the new Ceph target as it’s completed.
On paper, (I have not yet personally tested this), you could even take it a step farther: for all of your VMs that connect to the NFS share for their data, you could replace that NFS container (a single point of failure) with the cluster storage engine itself. There’s not a rule I know of that says you can’t. That way, your VM data is directly written to the engine at a lower latency than VM -> NFS -> ZFS/Ceph/etc
Oh I didn’t think the gap window is a bug - I was just acknowledging it, and I’m OK with it.
Definitely some ideas one day for the future but with my current time, architecture, and folks depending on certain services (and my own sanity with the many months I already spent on this), not really looking to re-do anything or wipe drives.
Just want to make the best of my ZFS situation for now - I know it can’t do everything that Ceph and GlusterFS can do.