Block I/O per Container Exposes Noisy Neighbors
Host disk latency can rise because one container is performing heavy reads or writes while every other service only sees the consequence.
storage
Volume Reference Counts Help Detect Orphaned Docker State
Old Docker volumes can consume storage after services are removed, and their names alone do not always reveal whether anything still depends on them.
Swap Provides Space, but Time Is the Price
Swap is sometimes treated as a direct replacement for RAM, but memory moved to storage has to be read back when active work needs it again. Swap creates room while introducing a time cost.
Do Not Let Log History Block Current Work
Logs are useful for future investigations, but unlimited retention can let the evidence system consume the resources required by the service itself. Observability needs its own storage budget.
ZFS Scrub, Resilver, Snapshot, and Replication Solve Different Failure Modes
A scrub detects latent corruption, a resilver reconstructs missing redundancy, a snapshot preserves an earlier dataset state, and replication puts that state somewhere else. Calling all four 'backup' hides the failures each one cannot solve.
SMART Health Is Different from Filesystem Free Space
A disk can have plenty of free capacity while the underlying SSD is reporting temperature or device-health problems.
Database Size Growth Is a Capacity Trend, Not an Emergency Metric
A database normally grows, so alerting on size alone would create noise while ignoring the important question of growth rate and disk headroom.
What Happens if Power Fails While Writing Flash?
It is easy to think of saving data as one indivisible event: write it and it is done. In reality, power can disappear in the middle of a write. The next boot then has to distinguish complete, incomplete, and usable state.
When a Disk Looks Slow, Inspect the Whole Read Path
When opening a file is slow, the disk is an obvious suspect. But data may cross a filesystem, mount, network gateway, and application layer before reaching the user. The symptom does not prove that storage is where the delay began.
IOPS and Throughput Answer Different Storage Questions
A database doing many tiny synchronous operations and a backup streaming large files can show similar disk utilization with very different access patterns.
Where Should a Message Wait for an Offline Node?
Communication is simpler if every node is assumed to be continuously available. Real nodes disappear because of power, radio conditions, or the environment. Then the design has to decide where a message waits and how long it remains relevant.
Retention Needs Both Time and Size Limits
Keeping thirty days of Prometheus data is useful until series growth causes the TSDB to consume more disk than the host can safely spare.