Synology Btrfs read-only state
Read-only status can follow disk errors, RAID degradation, metadata faults, power loss, or space exhaustion. It may preserve access long enough to copy critical data, but it does not prove the storage pool is stable.
Understand the symptom
Synology layers storage-pool RAID, Btrfs allocation trees, subvolumes, snapshots, and applications. A read-only transition can be triggered below or inside the filesystem. Recovery separates member health from RAID assembly and Btrfs metadata before any scrub or repair writes occur.
What you may see
DSM prevents ordinary writes after detecting an unsafe storage or filesystem state.
Reads may work while databases and packages require writable metadata.
Checksums, tree blocks, or underlying sectors cannot be read consistently.
An interrupted transaction or degraded member may be the initiating event.
Protect the source
Applications can immediately change metadata on an unstable volume.
A full read can accelerate a degrading disk before images exist.
Creating a replacement volume overwrites the structures needed to find files.
Do this now
Pause Drive, Hyper Backup, containers, VMs, databases, media indexing, and network writes.
Save pool, volume, Btrfs, disk, SMART, scrub, snapshot, and event details.
Preserve bay order, serials, removed members, replacements, cache devices, and chassis.
Use separate storage and avoid broad scans if the NAS is slow, disconnecting, or reporting I/O errors.
NEPFOSYS process
NEPFOSYS identifies whether member, RAID, pool, Btrfs, snapshot, or application metadata is blocking access.
Unstable members and metadata are preserved before write-based repair.
Btrfs trees, subvolumes, snapshots, and priority files are evaluated from protected copies.
A clear next step
Start a case with the exact symptoms, incident timeline, prior attempts, encryption details, and the files that matter most. NEPFOSYS will route the case to the appropriate DFW intake or nationwide mail-in path.
Start with a case reviewQuestions, answered
No. It limits writes but can coexist with unreadable sectors, missing members, or damaged Btrfs metadata.
Not before checking disk health and protecting unstable members. Scrubbing reads the full set and may also repair data.
They may preserve earlier metadata and file versions, but they use the same underlying pool and should not replace source preservation.
DFW local · Nationwide mail-in