Archived
beatzaplenty
a854412117
Covers node 1 hardware/network layout, LVM-thin -> ZFS migration path, Ceph as the future HA storage upgrade, and baseline SSH/firewall hardening.
47 lines
1.9 KiB
Markdown
47 lines
1.9 KiB
Markdown
# Storage: LVM-thin → ZFS, and the path to Ceph
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## Why move off LVM-thin
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Neither ZFS nor LVM-thin is shared storage — both are node-local. HA needs
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a VM's disk reachable from more than one node so it can restart elsewhere
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on host failure. LVM-thin has no answer for that. ZFS does, via
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replication; Ceph does natively.
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## Two paths to HA-capable storage
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| | ZFS + replication | Ceph |
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|---|---|---|
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| Nodes required | 1+ (replication needs 2+ targets) | 3+ |
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| Consistency | Async — snapshot-based, as often as every minute | Sync — real shared storage |
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| Data loss on failover | Whatever changed since last replication cycle | ~None |
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| Network needs | Normal cluster link | Fast dedicated network (see `03-networking.md`) |
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| Overhead | Low | Higher RAM/CPU/disk |
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Starting point: **ZFS + replication**. Revisit Ceph once 3 nodes exist or
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zero-RPO failover is worth the overhead.
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## Migration plan (old hardware → new hardware)
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Don't convert the old LVM-thin box in place. Rebuild fresh on new
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hardware with ZFS from the installer (mirror if 2+ disks), then move VMs:
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1. On the old host: `vzdump` each VM to a backup file (external drive,
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NFS share, or PBS if available).
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2. Copy backups to the new host.
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3. `qmrestore` onto the new ZFS storage — disks land as ZVOLs.
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Alternative if both hosts can see each other on the network: temporarily
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cluster them and use the GUI "Migrate" with a storage move (offline only
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— live migration doesn't cross storage types).
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## Later: handing Ceph-earmarked disks over
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Once nodes 2 and 3 are up and the Ceph-earmarked disks (see
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`01-hardware-node1.md`) can be pooled 3-node minimum:
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1. Wipe any temporary ZFS pool on those disks.
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2. Initialize Ceph across the 3 nodes.
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3. Create OSDs directly on the raw disks (no ZFS/RAID underneath).
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4. Migrate VMs that need zero-RPO failover from the ZFS-replicated tier
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onto Ceph-backed storage.
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