5a42643176
14 docs covering networking, VPN, storage, authentication, security, monitoring, secrets, CI/CD, backup/DR, compute, databases, and multi-tenancy. Each doc includes Mermaid diagrams, component tables, configuration references, decision rationale, and troubleshooting.
315 lines
12 KiB
Markdown
315 lines
12 KiB
Markdown
# Storage Architecture
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Last updated: 2026-03-24
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## Overview
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The cluster storage layer is built on TrueNAS ZFS at `10.0.10.15` (VMID 9000), providing both NFS shared storage and iSCSI block devices via democratic-csi. NFS serves ~100 application data directories for stateless services and those using file-based or SQLite databases, while iSCSI provides block devices for ~19 PVCs backing production MySQL and PostgreSQL databases. This hybrid approach optimizes for both performance (iSCSI for databases requiring ACID guarantees) and simplicity (NFS for everything else), with ZFS snapshot-based local protection and incremental offsite replication.
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## Architecture Diagram
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```mermaid
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graph TB
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subgraph TrueNAS["TrueNAS (10.0.10.15)<br/>VMID 9000, 16c/16GB"]
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ZFS_Main["ZFS Pool: main<br/>1.64 TiB<br/>32G + 7x256G + 1T disks"]
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ZFS_SSD["ZFS Pool: ssd<br/>~256GB SSD<br/>Immich ML, PostgreSQL hot data"]
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ZFS_Main --> NFS_Datasets["NFS Datasets<br/>~100 shares<br/>main/<service>"]
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ZFS_Main --> iSCSI_Datasets["iSCSI Datasets<br/>main/iscsi (zvols)<br/>main/iscsi-snaps"]
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NFS_Datasets --> NFS_Exports["NFS Exports<br/>managed by secrets/nfs_exports.sh"]
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iSCSI_Datasets --> iSCSI_Targets["iSCSI Targets<br/>SSH-managed via democratic-csi"]
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ZFS_SSD --> SSD_Data["Immich ML models<br/>PostgreSQL CNPG"]
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end
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subgraph K8s["Kubernetes Cluster"]
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CSI_NFS["democratic-csi-nfs<br/>StorageClass: nfs-truenas<br/>soft,timeo=30,retrans=3"]
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CSI_iSCSI["democratic-csi-iscsi<br/>StorageClass: iscsi-truenas<br/>SSH driver"]
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NFS_PV["NFS PersistentVolumes<br/>RWX, ~100 volumes"]
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iSCSI_PV["iSCSI PersistentVolumes<br/>RWO, ~19 volumes"]
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Pods["Application Pods"]
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DBPods["Database Pods<br/>PostgreSQL CNPG<br/>MySQL InnoDB"]
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end
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NFS_Exports -->|CSI driver| CSI_NFS
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iSCSI_Targets -->|CSI driver| CSI_iSCSI
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CSI_NFS --> NFS_PV
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CSI_iSCSI --> iSCSI_PV
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NFS_PV --> Pods
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iSCSI_PV --> DBPods
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style TrueNAS fill:#e1f5ff
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style K8s fill:#fff4e1
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style ZFS_Main fill:#c8e6c9
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style ZFS_SSD fill:#ffe0b2
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```
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## Components
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| Component | Version/Config | Location | Purpose |
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|-----------|---------------|----------|---------|
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| TrueNAS VM | VMID 9000, 16c/16GB | Proxmox host (10.0.10.15) | ZFS storage server |
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| ZFS pool `main` | 1.64 TiB usable | 32G + 7x256G + 1T disks | Primary storage for all services |
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| ZFS pool `ssd` | ~256GB SSD | Dedicated SSD | High-performance data (Immich ML, PostgreSQL) |
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| democratic-csi-nfs | Helm chart | Namespace: democratic-csi | NFS CSI driver |
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| democratic-csi-iscsi | Helm chart | Namespace: democratic-csi | iSCSI CSI driver (SSH mode) |
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| StorageClass `nfs-truenas` | RWX, soft mount | Cluster-wide | Default storage for apps |
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| StorageClass `iscsi-truenas` | RWO, block device | Cluster-wide | Databases only |
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| TF module `nfs_volume` | `modules/kubernetes/nfs_volume/` | Infra repo | NFS PV/PVC factory |
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## How It Works
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### NFS Storage Flow
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1. **Dataset creation**: NFS shares are created as ZFS datasets under `main/<service>` (e.g., `main/immich`, `main/nextcloud`)
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2. **Export configuration**: `/root/secrets/nfs_exports.sh` on TrueNAS generates `/etc/exports` with per-dataset exports (`/mnt/main/<service>`)
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3. **CSI provisioning**: democratic-csi-nfs mounts NFS shares and creates K8s PersistentVolumes
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4. **Terraform module**: Stacks use `modules/kubernetes/nfs_volume/` to declaratively create PV + PVC pairs:
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```hcl
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module "nfs_data" {
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source = "../../modules/kubernetes/nfs_volume"
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name = "immich-data"
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namespace = kubernetes_namespace.immich.metadata[0].name
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nfs_server = var.nfs_server # 10.0.10.15
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nfs_path = "/mnt/main/immich"
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}
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```
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5. **Pod mount**: Applications reference PVCs in their deployment specs
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6. **Mount options**: All NFS mounts use `soft,timeo=30,retrans=3` (set in StorageClass) to prevent indefinite hangs
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**CRITICAL**: Never use inline `nfs {}` blocks in pod specs — they default to `hard,timeo=600` which causes 10-minute hangs on network issues. Always use the `nfs-truenas` StorageClass via PVCs.
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### iSCSI Storage Flow
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1. **Zvol creation**: democratic-csi creates ZFS zvols under `main/iscsi/<pvc-name>` via SSH commands
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2. **Target setup**: TrueNAS iSCSI service exposes zvols as iSCSI LUNs
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3. **Initiator connection**: K8s nodes connect via open-iscsi, sessions managed by democratic-csi
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4. **Hardened timeouts**: All 5 nodes use relaxed iSCSI parameters (baked into cloud-init):
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- `replacement_timeout=300s` (not 120s default)
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- `noop_out_interval=10s`, `noop_out_timeout=15s`
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- HeaderDigest/DataDigest: `CRC32C,None`
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5. **Filesystem**: Pods format zvols as ext4 (or leave raw for database engines)
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6. **Exclusive access**: RWO only — zvol can only be attached to one node at a time
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**Why SSH driver**: The democratic-csi API driver has reliability issues. SSH driver execs `zfs create -V` commands directly, proven stable over 2+ years.
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### SQLite on NFS — Why It Fails
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SQLite uses `fsync()` to guarantee durability. NFS's soft mount + async semantics break this:
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- Soft mount returns success even if data is still in client cache
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- Network blips during fsync → incomplete writes → corruption
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- WAL mode helps but doesn't eliminate the race
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**Solution**: Use iSCSI for any SQLite database (Vaultwarden, plotting-book) or local disk (ephemeral).
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### Democratic-CSI Sidecar Resources
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The Helm chart spawns 17 sidecar containers (driver-registrar, external-provisioner, etc.) across controller + node DaemonSet pods. Each sidecar defaults to `resources: {}`, which gets LimitRange defaults of 256Mi.
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**Fix**: Set explicit resources in `values.yaml`:
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```yaml
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csiProxy: # TOP-LEVEL key, not nested
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resources:
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requests:
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memory: "32Mi"
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limits:
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memory: "32Mi"
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controller:
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externalProvisioner:
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resources:
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requests: {memory: "64Mi"}
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limits: {memory: "64Mi"}
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# ... repeat for all sidecars
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```
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Total footprint: ~1.5Gi → ~400Mi.
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## Configuration
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### Key Files
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| Path | Purpose |
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|------|---------|
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| `/root/secrets/nfs_exports.sh` | TrueNAS: generates `/etc/exports` with all service shares |
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| `stacks/democratic-csi/` | Terraform stack for both CSI drivers |
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| `modules/kubernetes/nfs_volume/` | Reusable module for NFS PV/PVC creation |
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| `config.tfvars` | Variable `nfs_server = "10.0.10.15"` shared by all stacks |
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| `/var/lib/kubelet/config.yaml` | K8s nodes: iSCSI hardening params applied here |
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| `modules/create-template-vm/cloud_init.yaml` | Cloud-init template: bakes iSCSI settings into new nodes |
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### Vault Paths
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| Path | Contents |
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|------|----------|
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| `secret/viktor/truenas_ssh_key` | SSH private key for democratic-csi SSH driver |
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| `secret/viktor/truenas_root_password` | TrueNAS root password (web UI access) |
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### Terraform Stacks
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- **`stacks/democratic-csi/`**: Deploys both NFS and iSCSI CSI drivers
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- All application stacks reference NFS volumes via `module "nfs_<name>"` calls
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- iSCSI PVCs created implicitly by StatefulSets (MySQL, PostgreSQL) using `iscsi-truenas` StorageClass
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### NFS Export Management
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NFS exports are NOT managed by Terraform. To add a new service:
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1. SSH to TrueNAS: `ssh root@10.0.10.15`
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2. Edit `/root/secrets/nfs_exports.sh`
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3. Add dataset + export entry:
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```bash
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create_nfs_export "main/<service>" "/mnt/main/<service>"
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```
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4. Run the script: `/root/secrets/nfs_exports.sh`
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5. Verify: `showmount -e 10.0.10.15`
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## Decisions & Rationale
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### Why NFS for Most Workloads?
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- **Simplicity**: No volume provisioning delays, instant mounts
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- **RWX support**: Multiple pods can share one volume (Nextcloud, Immich)
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- **ZFS benefits**: Snapshots, compression, dedup all work at dataset level
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- **Good enough**: For SQLite on NFS specifically, we accept the risk for low-value data (logs, caches) but mandate iSCSI for critical DBs
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### Why iSCSI for Databases?
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- **ACID guarantees**: Block device + local filesystem = real fsync
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- **Performance**: No NFS protocol overhead for random I/O
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- **Tested**: PostgreSQL CNPG and MySQL InnoDB Cluster both run on iSCSI, zero corruption in 2+ years
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### Why SSH Driver Over API?
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The democratic-csi API driver (`driver: freenas-api-iscsi`) has these issues:
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- Requires TrueNAS API credentials in plaintext ConfigMap
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- Fails silently when API schema changes between TrueNAS versions
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- No retry logic on transient API errors
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SSH driver (`driver: freenas-ssh`) is simpler:
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- Direct `zfs` commands, no API translation layer
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- SSH key auth (Vault-managed)
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- Deterministic error messages
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### Why Soft Mount for NFS?
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Hard mounts with default `timeo=600` (10 minutes) cause:
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- 10-minute pod startup delays if NFS server is unreachable
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- `kubectl delete pod` hangs for 10 minutes
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- Kernel task hangs blocking node operations
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Soft mount (`soft,timeo=30,retrans=3`) trades availability for responsiveness:
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- Max 90s hang (30s × 3 retries)
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- Operations return EIO after timeout → app can handle error
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- Acceptable for non-critical data paths
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**Critical paths**: Databases use iSCSI (not NFS), so soft mount never affects data integrity.
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## Troubleshooting
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### NFS Mount Hangs
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**Symptom**: Pod stuck in `ContainerCreating`, `df -h` hangs on NFS mount
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**Diagnosis**:
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```bash
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# On K8s node
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mount | grep nfs
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showmount -e 10.0.10.15
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# Check NFS server
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ssh root@10.0.10.15
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zfs list | grep main/<service>
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cat /etc/exports | grep <service>
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```
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**Fix**:
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1. Verify dataset exists: `zfs list main/<service>`
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2. Verify export: `grep <service> /etc/exports`
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3. If missing: re-run `/root/secrets/nfs_exports.sh`
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4. Restart NFS server: `service nfs-server restart`
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### iSCSI Session Drops
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**Symptom**: PostgreSQL/MySQL pod restarts, iSCSI reconnection loops
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**Diagnosis**:
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```bash
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# On K8s node
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iscsiadm -m session
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dmesg | grep iscsi
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journalctl -u iscsid -f
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```
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**Fix**:
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1. Check TrueNAS iSCSI service: WebUI → Sharing → iSCSI → Targets
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2. Verify hardened timeouts: `iscsiadm -m node -o show | grep timeout`
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3. If defaults: re-apply cloud-init or manually update `/etc/iscsi/iscsid.conf`
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4. Restart session:
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```bash
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iscsiadm -m node -u
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iscsiadm -m node -l
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```
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### Democratic-CSI Sidecar OOMKill
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**Symptom**: `kubectl describe pod` shows sidecar containers OOMKilled
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**Diagnosis**:
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```bash
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kubectl get events -n democratic-csi | grep OOM
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kubectl top pod -n democratic-csi
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```
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**Fix**:
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1. Set explicit resources in Helm values (see "Democratic-CSI Sidecar Resources" above)
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2. Apply: `terragrunt apply` in `stacks/democratic-csi/`
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### SQLite Corruption on NFS
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**Symptom**: `database disk image is malformed`, checksum errors
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**Diagnosis**:
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```bash
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# In pod
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sqlite3 /data/db.sqlite "PRAGMA integrity_check;"
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```
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**Fix**: Migrate to iSCSI
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1. Create iSCSI PVC in Terraform stack
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2. Restore from backup to new volume
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3. Update deployment to use new PVC
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4. Delete old NFS PVC
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### Slow NFS Performance
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**Symptom**: High latency on file operations, `iostat` shows NFS wait times
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**Diagnosis**:
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```bash
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# On TrueNAS
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zpool iostat -v 5
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arc_summary | grep "Hit Rate"
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# On K8s node
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nfsiostat 5
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```
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**Optimization**:
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1. Check ZFS ARC hit rate (should be >90%)
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2. Move hot datasets to SSD pool: `zfs send main/<dataset> | zfs recv ssd/<dataset>`
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3. Tune NFS mount: add `rsize=1048576,wsize=1048576` to StorageClass `mountOptions`
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## Related
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- **Runbooks**:
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- `docs/runbooks/restore-postgresql.md`
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- `docs/runbooks/restore-mysql.md`
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- `docs/runbooks/recover-nfs-mount.md`
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- **Architecture**: `docs/architecture/backup-dr.md` (backup strategy using ZFS snapshots)
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- **Reference**: `.claude/reference/service-catalog.md` (which services use NFS vs iSCSI)
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