PCA PCA Storage & Retention 3

Question 1

What file format do Prometheus TSDB chunk files use?

Accepted Answer

A custom binary format optimized for time-series compression

Answer

Apache Parquet

Answer

Protocol Buffers

Answer

Apache Arrow

Question 2

What happens to the WAL when Prometheus shuts down cleanly?

Accepted Answer

It is checkpointed so replay on restart is faster

Answer

It is deleted to free disk space

Answer

It is converted into a permanent TSDB block

Answer

It is sent to the remote_write endpoint

Question 3

Which Prometheus command-line flag specifies the directory where TSDB data is stored?

Accepted Answer

--storage.tsdb.path

Answer

--data.dir

Answer

--tsdb.storage-dir

Answer

--storage.local.path

Question 4

What is the purpose of the `meta.json` file inside a Prometheus TSDB block directory?

Accepted Answer

It stores the block's time range, version, statistics, and compaction history

Answer

It lists the active scrape targets during that block's period

Answer

It holds the alert rules evaluated during that time range

Answer

It caches the results of expensive PromQL queries

Question 5

Why might setting a very short TSDB retention period cause high disk I/O in Prometheus?

Accepted Answer

Frequent block deletions and compactions run more often to purge data quickly

Answer

More WAL segments are written per second at shorter retention

Answer

Remote write batching is disabled when retention is under 24 hours

Answer

Prometheus re-indexes all series more frequently at short retention

Question 6

Which tool is commonly used alongside Prometheus to provide long-term, highly-available storage without modifying Prometheus itself?

Accepted Answer

Thanos

Answer

Loki

Answer

Jaeger

Answer

Elasticsearch