Filesystems · Cluster
Data Integrity
Checksums, scrubbing, and silent corruption.
- 01 Silent Data Corruption and What Device Error Reporting Misses Why a read can succeed and still return the wrong bytes, how drives separate correctable from uncorrectable errors, and which corruption classes no device is able to report.
- 02 Checksum Strength: What CRC32C and SHA-256 Each Guarantee The detection guarantees a cyclic redundancy check actually provides, the different guarantee a cryptographic hash provides, and the cost of moving from one to the other.
- 03 Checksum Placement: Block Pointers, Metadata Trees, and Payloads Where a filesystem can store a block checksum, why the pointer is usually the right home for it, and how each placement choice changes what a torn write can do.
- 04 Read-Path Verification and What Happens When a Block Fails The ordering constraints a verifying read must satisfy, the error classes a mismatch can be sorted into, and why retrying a failed checksum is usually pointless.
- 05 Checksum Granularity and the Read-Modify-Write Penalty How the size of the region one checksum covers sets both the precision of damage reporting and the cost of small overwrites, and why 4 KiB sectors made granularity a hard constraint.
- 06 Scrub Passes: Finding Latent Damage Before It Is Needed What a scrub actually reads and in what order, why it must walk metadata rather than sweep the device, and how a pass is throttled so it does not starve foreground I/O.
- 07 Self-Healing Reads: Reconstructing a Copy From Redundancy How a filesystem repairs a damaged block during a read, what the repair costs on mirrored and parity layouts, and why the repair itself can fail.
- 08 Hash Trees and the Root of Trust in a Checksummed Filesystem Why per-block checksums need a chain to a single trusted value, how Merkle trees make tampering localisable, and what the root itself has to be protected against.
- 09 End-to-End Protection Information and Where the Checksum Stops How T10 protection information moves a checksum onto the wire with the data, what the guard, application tag, and reference tag each defend, and why the host still needs its own check.
- 10 Checksum Blind Spots: Misdirected Writes and Lost Updates The fault classes that survive a correct checksum, from acknowledged writes that never landed to corruption introduced above the filesystem, and the ordering machinery each one needs.