zosstorage

One-shot disk provisioning utility intended for initramfs. It discovers eligible disks, plans a GPT layout based on a chosen topology, creates filesystems, mounts them under a predictable scheme, and emits a machine-readable report. Safe-by-default with a non-destructive preview mode.

Status: apply mode implemented. Partition application (sgdisk), filesystem creation (vfat/btrfs/bcachefs), mount scheme with subvolumes, and optional fstab writing are available. Preview mode remains supported.

Key modules

• CLI and entrypoint:
  • src/cli/args.rs
  • src/main.rs
• Orchestration and preview JSON:
  • src/orchestrator/run.rs
• Configuration loader, overlays, defaults:
  • src/config/loader.rs
• Device discovery (sysfs + regex filters, removable policy):
  • src/device/discovery.rs
• Idempotency detection and emptiness checks:
  • src/idempotency/mod.rs
• Partition planning (topology-aware):
  • src/partition/plan.rs
• Filesystem planning/creation and mkfs integration:
  • src/fs/plan.rs
• Mount planning and application (skeleton):
  • src/mount/ops.rs

Features at a glance

• Topology-driven planning with built-in defaults: BtrfsSingle, BcachefsSingle, DualIndependent, Bcachefs2Copy, BtrfsRaid1, SsdHddBcachefs
• Non-destructive preview: --show/--report outputs JSON summary (disks, partition plan, filesystems, planned mountpoints)
• Safe discovery: excludes removable media by default (USB sticks) unless explicitly allowed
• Config-optional: the tool runs without any YAML; sensible defaults are always present and may be overridden/merged by config

Requirements

• Linux with /proc and /sys mounted (initramfs friendly)
• External tools discovered at runtime:
  • blkid (for probing UUIDs and signatures)
  • sgdisk (for GPT application)
  • mkfs.vfat, mkfs.btrfs, bcachefs (for formatting)
  • udevadm (optional; for settle after partitioning)
• Tracing/logging to stderr by default; optional file at /run/zosstorage/zosstorage.log

Install and build

• System Rust toolchain: cargo build --release

Binary is target/release/zosstorage.

CLI usage

• Topology selection (config optional): -t, --topology btrfs-single|bcachefs-single|dual-independent|bcachefs-2copy|btrfs-raid1|ssd-hdd-bcachefs
• Preview (non-destructive): --show Print JSON summary to stdout --report PATH Write JSON summary to a file
• Discovery policy: --allow-removable Include removable devices (USB) during discovery
• Tracing/logging: -l, --log-level LEVEL error|warn|info|debug (default: info) -L, --log-to-file Also write logs to /run/zosstorage/zosstorage.log
• Other: -c, --config PATH Merge a YAML config file (overrides defaults) -s, --fstab Enable writing /etc/fstab entries (when mounts are applied) -a, --apply Perform partitioning, filesystem creation, and mounts (destructive) -f, --force Present but not implemented (returns an error)

Examples

• Single disk plan with debug logs: sudo ./zosstorage --show -t btrfs-single -l debug
• RAID1 btrfs across two disks; print and write summary: sudo ./zosstorage --show --report /run/zosstorage/plan.json -t btrfs-raid1 -l debug -L
• SSD+HDD bcachefs plan, include removable devices (for lab cases): sudo ./zosstorage --show -t ssd-hdd-bcachefs --allow-removable -l debug
• Quiet plan to file: sudo ./zosstorage --report /run/zosstorage/plan.json -t dual-independent
• Apply single-disk btrfs (DESTRUCTIVE; wipes target disk): sudo ./zosstorage --apply -t btrfs-single

Preview JSON shape (examples)

1. Already provisioned (idempotency success): { "version": "v1", "timestamp": "2025-09-26T12:34:56Z", "status": "already_provisioned", "state": { ... full StateReport JSON ... } }

2. Planned (not yet provisioned): { "version": "v1", "timestamp": "2025-09-26T12:34:56Z", "status": "planned", "topology": "btrfs_raid1", "alignment_mib": 1, "require_empty_disks": true, "disks": [ { "path": "/dev/nvme0n1", "size_bytes": 1000204886016, "rotational": false, "model": "...", "serial": "..." }, { "path": "/dev/nvme1n1", "size_bytes": 1000204886016, "rotational": false, "model": "...", "serial": "..." } ], "partition_plan": [ { "disk": "/dev/nvme0n1", "parts": [ { "role": "bios_boot", "size_mib": 1, "gpt_name": "zosboot" }, { "role": "esp", "size_mib": 512, "gpt_name": "zosboot" }, { "role": "data", "size_mib": null, "gpt_name": "zosdata" } ] }, { "disk": "/dev/nvme1n1", "parts": [ { "role": "data", "size_mib": null, "gpt_name": "zosdata" } ] } ], "filesystems_planned": [ { "kind": "vfat", "from_roles": ["esp"], "label": "ZOSBOOT" }, { "kind": "btrfs", "from_roles": ["data"], "devices_planned": 2, "label": "ZOSDATA" } ], "mount": { "scheme": "per_uuid", "base_dir": "/var/cache", "fstab_enabled": false, "root_mount_template": "/var/mounts/{UUID}", "final_targets": ["/var/cache/system", "/var/cache/etc", "/var/cache/modules", "/var/cache/vm-meta"] } }

Defaults and policies

• Device selection defaults (see src/config/loader.rs): include_patterns: ^/dev/sd\w+, ^/dev/nvme\w+n\d+, ^/dev/vd\w+$ exclude_patterns: ^/dev/ram\d+, ^/dev/zram\d+, ^/dev/loop\d+, ^/dev/fd\d+ allow_removable: false (USB excluded unless --allow-removable) min_size_gib: 10
• Partitioning defaults: alignment_mib: 1 bios_boot: enabled (1 MiB), gpt_name: zosboot esp: 512 MiB, label: ZOSBOOT, gpt_name: zosboot data: gpt_name: zosdata cache: gpt_name: zoscache (only used in SSD+HDD topology)
• Filesystem defaults: vfat (ESP) label: ZOSBOOT btrfs (data) label: ZOSDATA bcachefs (data/cache) label: ZOSDATA
• Mount scheme:
  • Root mounts (runtime only): each data filesystem is mounted at /var/mounts/{UUID}
    • btrfs root options: rw,noatime,subvolid=5
    • bcachefs root options: rw,noatime
  • Subvolume mounts (from the primary data filesystem only) to final targets:
    • /var/cache/system
    • /var/cache/etc
    • /var/cache/modules
    • /var/cache/vm-meta
  • Subvolume mount options:
    • btrfs: -o rw,noatime,subvol={name}
    • bcachefs: -o rw,noatime,X-mount.subdir={name}
  • /etc/fstab generation is disabled by default; when enabled, only the four subvolume mounts are written (UUID= sources, deterministic order)

Tracing and logs

• stderr logging level controlled by -l/--log-level (info by default)
• optional file logging with -L/--log-to-file at /run/zosstorage/zosstorage.log
• Debug spans provide insight into discovery, idempotency, planning, and tool invocations

Extending and execution plan

• Near-term:
  • Implement sgdisk partition apply and udev settle
  • Pass btrfs raid profile flags -m/-d from config (raid1, none) to mkfs
  • Create per-UUID mount targets; persist fstab when enabled
  • Atomic report write via tempfile+rename
• Longer-term:
  • Dry-run mode with richer diffs
  • Richer schema for disks/partitions/filesystems in the report
  • Additional filesystem and tuning support

Safety model

• Preview mode never mutates block devices
• Emptiness checks guard destructive actions (skipped only in preview)
• Reserved labels and GPT names validated to reduce risk

Troubleshooting

• No eligible disks found: adjust include/exclude patterns or use --allow-removable for test media
• Removable media excluded: either add --allow-removable or exclude it explicitly via config patterns
• blkid missing: install util-linux; preview can still plan but cannot capture UUIDs for mkfs outputs
• bcachefs command missing: install bcachefs-tools or skip the SSD+HDD topology

License

• TBD (add your preferred license)