CassandraAdmin

Question 1

Purpose of seed nodes? (2)

Answer 1

1. Bootstrapping (adding new node) 2. In case gossip loses its mind

Question 2

What is the leveled compaction multiplier?

Answer 2

10x per level

Question 3

What type of workload is best for leveled comparison?

Answer 3

read-heavy

Question 4

Which compaction strategy saves the most disk space?

Answer 4

leveled compaction

Question 5

The biggest problem with leveled compaction?

Answer 5

I/O intensity

Question 6

Can you create a keyspace by specifying a non-existent multi-dc keyspace?

Answer 6

Yes.

Question 7

What does sstabledump do?

Answer 7

Dump contents of a given SSTable to standard output in JSON format. Good for diagnostics. Includes tombstones.

Question 8

What are the 4 states for each node?

Answer 8

joining, leaving, up, and down

Question 9

By default now many vnodes does each node have?

Answer 9

128 per Cassandra quiz. In my experience, it has been 256.

Question 10

cassandra.yaml parameter that configures vnodes?

Answer 10

num_tokens

Question 11

What does snitch do?

Answer 11

determines each node’s rack and data center

Question 12

3 types of snitch?

Answer 12

SimpleSnitch, PropertFileSnitch, DynamicSnitch

Question 13

With RF=2, how many nodes must respond with success using consistency level quorum to indicate a successful operation?

Answer 13

2

Question 14

What is the default time for a node to store a hint?

Answer 14

3 hours

Question 15

Is hinted handoff enabled or disabled by default?

Answer 15

Enabled.

Question 16

Read repair ALWAYS occurs in which consistency level?

Answer 16

ALL

Question 17

SStable stands for…

Answer 17

Sorted Stream Table

Question 18

What does the partition summary store?

Answer 18

Byte offsets into the partition index

Question 19

Which structures are stored on disk?

Answer 19

SStable and partition index (also commit log).

Question 20

What is the partition index?

Answer 20

The structure on disk that contains bytes offsets for sstables.

Question 21

What is the index of the partition index?

Answer 21

The partition summary, stored in ram to limit search in partition index. summary->index->sstable

Question 22

Structures stored in ram?

Answer 22

key cache, partition summary, bloom filter (bloom filter is off heap)

Question 23

What does CPU wait mean?

Answer 23

Roughly the amount of time a task has to wait on CPU resources.

Question 24

What does dstat show?

Answer 24

CPU, disk I/O, network for all processes

Question 25

Which nodetool sub-command gives datacenter and rack information?

Answer 25

nodetool info

Question 26

Where can logging levels be set?

Answer 26

nodetool setlogginglevel or cassandra.yaml

Question 27

Should GC logging be turned on by default?

Answer 27

No.

Question 28

What triggers size tiered compaction?

Answer 28

of sstables