DevOps · Cluster
Infrastructure Operations
Patching, backups, and disaster recovery.
- 01 Conffile Conflicts During Package Upgrades How dpkg and rpm decide whether a configuration file has been edited locally, why neither will merge, and how unattended upgrades end up keeping stale configuration.
- 02 Dependency Resolution and Partial Upgrades Why installing one package can remove another, how versioned dependencies and library sonames constrain an upgrade, and what differs between upgrade commands.
- 03 Reboot-Required and Live Kernel Patching What the reboot flag actually tracks, why a replaced shared library keeps running inside existing processes, and which kernel changes a live patch cannot make.
- 04 Crash-Consistent and Application-Consistent Backups What a point-in-time image really contains, why journal replay only repairs the filesystem, and how to quiesce a running service without stopping it.
- 05 Incremental Backup Chains and Restore Depth How changed-block tracking works, why deduplicated storage makes deletion expensive, and why restore time grows with the number of links in the chain.
- 06 Checksum Verification and Restore Drills Distinguishing repository integrity from data verification and from a real restore, how much sampling is statistically worth doing, and what no checksum can detect.
- 07 Log Shipping and the Recovery Point Objective How the commit acknowledgement ladder sets the true data-loss window, why a WAL archive lags by a whole segment, and how to measure the gap rather than assume it.
- 08 Recovery Ordering for Multi-Service Estates Why a restore is a topological problem, how legitimate designs create dependency cycles, and why the credentials needed to restore usually live inside the thing being restored.
- 09 Fencing and Quorum in Automated Failover Why a new primary must be able to prove the old one cannot write, how leases fail when a machine is paused rather than dead, and where quorum buys safety more cheaply.
- 10 Key Escrow for Encrypted Backups How envelope encryption separates the key that protects data from the key that protects keys, why rotation is cheap until it is not, and how escrow can outlive the system it protects.