This document summarizes a presentation about monitoring Cassandra systems. It discusses gathering metrics from Cassandra using JMX and nodetool, including thread pool statistics, latency histograms, and metric types. It also provides an overview of the Cassandra read/write process involving memtables and SSTables.

1. Monitor Everything
By: Chris Lohfink
Cassandra Summit 2014

2. About Me
● Sr. Engineer at Pythian
o Lead of Cassandra Practice
● Remote in Minnesota
● DataStax MVP for Cassandra ‘14
● Interests
o Java, Clojure, Python dev
o Data science
o Hobbyist electronics
#CassandraSummit 2014

3. About Pythian
Pythian is a global data outsourcing and consulting company that
specializes in optimizing and managing mission-critical data systems.
Pythian blends the world’s leading data experts with advanced, secure
service delivery processes to create the industry’s best standard of care
for its clients.
Since its inception, Pythian has managed some of the world’s largest,
most business-critical data infrastructures.
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10,000
Pythian currently manages more than 10,000
systems.
350
Pythian currently employs more than 350 people
in 25 countries worldwide.
1997
Pythian was founded in 1997

4. About Cassandra
● No Single Point of Failure
● Fault Tolerant
● Awesome properties for an operations team who does
not want to get up at 3am
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5. About Cassandra
● Nothing should be set up and forgotten about
● Easy to do with Cassandra though
o Fault tolerance on properly configured setup handles
single node being down or having temp performance
issues
o No back pressure on writes until there is a lot of
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trouble

6. Utilize the fault tolerance buffer
● Need to observe and react to current issues
● Predict future issues
● Divide this into two approaches
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o Proactive
o Reactive

7. Proactive
● Daily & Weekly checkups to prevent, and
predict problems
o Capacity
o Performance bottlenecks
o Data Modeling issues
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8. Reactive
● Something about best laid plans…
o Hardware failures
o Bugs
o Malicious or Non-Malicious users
● Alarms, Pager Duty
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9. Common element
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● Data is needed
o form alerts
o find anomalies
o trending
o debugging

10. Metrics
● Window to the application
o Bridge the gap - Coda Hale
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11. Gathering Metrics
SOURCES
Cassandra Environment
OpsCenter Logs
JMX CPU, Disk, Network
Nodetool JVM, GC
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12. Metrics
but of course…
Without context, the data is just pretty graphs

13. JMX
● Java Management Extensions
● Complex… very engineered
● Resources represented as objects with
attributes and operations
● Used for monitoring or as input
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14. JMX
● The annoying gateway to metrics
○ Poor tooling - requires java
○ Slow, Memory Leaks
○ Historically and currently frustrating for ops (pre 2.0.8)
Cassandra
Init connection to port
7199 Reply with hostname:port for
1024-65535
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RMI connection
Client (You)
Gets new hostname:port,
drops old connection and
attempts to connect
7199
7199
Connected!

15. JMX
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● Visual
o jconsole
o visualvm
● Command line
o jmxterm
o jmxsh
● MX4J
● Jolokia

16. JMX
[domain]:[key]=[value],[key2]=[value2]...
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17. JMX
[domain]:[key]=[value],[key2]=[value2]...
com.pythian:site=blog,type=views,target=post1
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18. JMX
[domain]:[key]=[value],[key2]=[value2]...
com.pythian:site=blog,type=views,target=post1
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19. JMX
[domain]:[key]=[value],[key2]=[value2]...
com.pythian:site=blog,type=views,target=post1
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20. JMX Domains
org.apache.cassandra.
● db
● internal
● net
● request
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21. JMX Beans
org.apache.cassandra.metrics
● db
● internal
● net
● request
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22. JMX
org.apache.cassandra.metrics :type=
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● Cache
● Client
● ClientRequest
● ClientRequestMetrics
● ColumnFamily
● CommitLog
● Compaction
● DroppedMessage
● FileCache
● Keyspace
● Storage
● ThreadPools

23. JMX
org.apache.cassandra.metrics
type=*, scope=*, name=*,
type=ThreadPools, path=*, scope=*, name=*,
type=ColumnFamily, keyspace=*, scope=*, name=*,
type=Keyspace, keyspace=*, name=*,
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24. Metrics
● Toolkit called metrics for metrics
o By Coda Hale @ Yammer
● Easy to use
● Easy to read (if you know java)
● Popular
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25. Types of Metrics
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● Gauge
o instantaneous value
● Counter
o number that can be incremented & decremented
● Meter
o rate of events over time (1/5/15 min moving avg)
● Histogram
o representation of statistical distribution
 50, 75, 95, 98, 99, 99.9 percentile
 average, median, min, max, standard deviation
● Timer
o rate of events (meter)
o histogram of duration

26. JMX
#CassandraSummit 2014
75th percentile is 683 MICROSECONDS
(75% took 683us or less)
One minute rate is 13,915 calls per SECOND

27. JMX
● Overwhelming at first
● Hard to tell what they mean without the source
● Moves around a lot
● Fortunately there is nodetool
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28. Nodetool
● JMX command line wrapper
● Many options
● Operations and diagnostic procedures
● For reactive analysis
o ad hoc, spot checks
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29. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
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Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 0
COUNTER_MUTATION 0

30. Staged Event Driven Architecture
● Decomposes complex event system
● Set of stages (thread pools)
● Queue between each
● Shares a lot of pros cons as SOA
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31. Staged Event Driven Architecture
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ReadStage
Threads
x32
Client Request
RequestResponse
Threads
ReadRepairStage
Threads
Messaging
Service
Node 2
Node 1 Node 1
Node 1
= Task

32. Staged Event Driven Architecture
● Possible to overrun the processing capabilities of a
stage that is not in the requests feedback loop (i.e.
ReadRepairStage)
#CassandraSummit 2014

33. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
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Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 0
COUNTER_MUTATION 0

34. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
#CassandraSummit 2014
Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 0
COUNTER_MUTATION 0

35. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
#CassandraSummit 2014
Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 0
COUNTER_MUTATION 0

36. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
#CassandraSummit 2014
Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 0
COUNTER_MUTATION 0

37. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
#CassandraSummit 2014
Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 0
COUNTER_MUTATION 0

38. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
#CassandraSummit 2014
Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 0
COUNTER_MUTATION 0

39. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 0
COUNTER_MUTATION 0
#CassandraSummit 2014
RequestResponse
Threads

40. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 113702 0 0
RequestResponseStage 0 0 0 0 0
MutationStage 0 0 164503 0 0
...
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 0 0 0
Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
...
REQUEST_RESPONSE 1
COUNTER_MUTATION 0
#CassandraSummit 2014
RequestResponse
Threads

41. Nodetool tpstats
nodetool tpstats
org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name=
{ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks}
#CassandraSummit 2014
More at:
http://www.evidencebasedit.com/guide-to-cassandra-thread-pools

42. Nodetool cfhistograms
nodetool cfhistograms {keyspace} {table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
SSTables per Read
1 sstables: 98554
2 sstables: 4534
Write Latency (microseconds)
No Data
Read Latency (microseconds)
10 us: 2
12 us: 17
14 us: 96
17 us: 208
20 us: 677
24 us: 3081
29 us: 4552
35 us: 3559

43. Read Write Path mile high overview
Memtable SSTable
#CassandraSummit 2014
Writes Reads

44. Read Write Path mile high overview
Memtable SSTable
#CassandraSummit 2014
Writes Reads

45. Read Write Path mile high overview
Memtable SSTable
#CassandraSummit 2014
Writes Reads

46. Read Write Path mile high overview
Memtable SSTable
#CassandraSummit 2014
Writes Reads

47. Read Write Path mile high overview
Memtable SSTable
#CassandraSummit 2014
Writes Reads

48. Nodetool cfhistograms
nodetool cfhistograms {keyspace} {table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
SSTables per Read
1 sstables: 98554
2 sstables: 4534
Write Latency (microseconds)
No Data
Read Latency (microseconds)
10 us: 2
12 us: 17
14 us: 96
17 us: 208
20 us: 677
24 us: 3081
29 us: 4552
35 us: 3559

49. Nodetool cfhistograms 1.1
nodetool cfhistograms {keyspace} {table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
Offset SSTables Write Latency Read Latency Row Size Column Count
1 3579 0 0 0 0
2 0 0 0 0 0
. . .
35 0 0 0 0 0
42 0 0 27 0 0
50 0 0 187 0 0
60 0 10 460 0 0
72 0 200 689 0 0
86 0 663 552 0 0
103 0 796 367 0 0
124 0 297 736 0 0
149 0 265 243 0 0
179 0 460 263 0 0
. . .
25109160 0 0 0 0 0
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50. Nodetool cfhistograms
#CassandraSummit 2014
https://gist.github.com/clohfink/6068003

51. Nodetool cfhistograms 2.1
nodetool cfhistograms {keyspace} {table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
Keyspace/Table histograms
Percentile SSTables Write Latency Read Latency Partition Size Cell Count
(micros) (micros) (bytes)
50% 1.00 10.00 524.00 310 5
75% 1.00 11.75 888.00 310 5
95% 1.00 15.00 4843.75 310 5
98% 1.00 17.00 9658.90 310 5
99% 1.00 19.00 12306.47 310 5
Min 0.00 0.00 68.00 30 0
Max 2.00 219386.00 45383.00 310 5
#CassandraSummit 2014

52. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

53. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

54. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

55. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

56. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
SSTables in each level: [14/4, 1, 0, …, 0]
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

57. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

58. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

59. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

60. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

61. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

62. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

63. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

64. Nodetool cfstats
nodetool cfstats {-i} {keyspace}.{table}
org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table}
#CassandraSummit 2014
Keyspace: Keyspace1
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Tasks: 0
Table: Standard1
SSTable count: 3
Space used (live), bytes: 9088955
Space used (total), bytes: 9088955
Space used by snapshots (total), bytes: 0
SSTable Compression Ratio: 0.3672150946
Memtable cell count: 0
Memtable data size, bytes: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending tasks: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used, bytes: 11688
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice: 0.0
Average tombstones per slice: 0.0

65. Nodetool proxyhistograms
nodetool proxyhistograms
org.apache.cassandra.metrics:type=ClientRequest,scope={Read|Write|RangeSlice},name=Latency
#CassandraSummit 2014
$ nodetool proxyhistograms
proxy histograms
Read Latency (microseconds)
61214 us: 1
Write Latency (microseconds)
103 us: 22
124 us: 142
149 us: 297
179 us: 1190
215 us: 1823
258 us: 2091
...

66. Nodetool
#CassandraSummit 2014
Much more!!
http://www.datastax.com/documentation/cassa
ndra/2.0/cassandra/tools/toolsNodetool_r.html

67. Reporting Interface
#CassandraSummit 2014
Default Addons Community
JMX Ganglia Cassandra StatsD NewRelic Splunk
Console Graphite Cloudwatch Kafka Riemann TempDB
Csv Munin Riak InfluxDB Sematext
Slf4j MongoDB OpenTSDB Librato … MORE

68. Reporting Interface
● Configurable with yaml
o console, csv, ganglia, graphite, riemann
● Create reporter with premain agent
o compiling new jar with manifest
o add to classpath
o add javaagent in cassandra-env.sh
#CassandraSummit 2014

69. Garbage Collection
● Death, Taxes, and a stop the world GC
● Common issue to all JVM based applications
#CassandraSummit 2014

70. Garbage Collection
Enable gc logging
● Virtually no overhead
● Can be very helpful in diagnosing
performance issues
#CassandraSummit 2014

71. Garbage Collection
JVM_OPTS="$JVM_OPTS -XX:+PrintGCDetails"
JVM_OPTS="$JVM_OPTS -XX:+PrintGCDateStamps"
JVM_OPTS="$JVM_OPTS -XX:+PrintHeapAtGC"
JVM_OPTS="$JVM_OPTS -XX:+PrintTenuringDistribution"
JVM_OPTS="$JVM_OPTS -XX:+PrintGCApplicationStoppedTime"
JVM_OPTS="$JVM_OPTS -XX:+PrintPromotionFailure"
JVM_OPTS="$JVM_OPTS -XX:PrintFLSStatistics=1"
JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc-`date +%s`.log"
JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc.log"
JVM_OPTS="$JVM_OPTS -XX:+UseGCLogFileRotation"
JVM_OPTS="$JVM_OPTS -XX:NumberOfGCLogFiles=10"
JVM_OPTS="$JVM_OPTS -XX:GCLogFileSize=10M"
#CassandraSummit 2014

72. Garbage Collection
JVM_OPTS="$JVM_OPTS -XX:+PrintGCDetails"
JVM_OPTS="$JVM_OPTS -XX:+PrintGCDateStamps"
JVM_OPTS="$JVM_OPTS -XX:+PrintHeapAtGC"
JVM_OPTS="$JVM_OPTS -XX:+PrintTenuringDistribution"
JVM_OPTS="$JVM_OPTS -XX:+PrintGCApplicationStoppedTime"
JVM_OPTS="$JVM_OPTS -XX:+PrintPromotionFailure"
JVM_OPTS="$JVM_OPTS -XX:PrintFLSStatistics=1"
JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc-`date +%s`.log"
JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc.log"
JVM_OPTS="$JVM_OPTS -XX:+UseGCLogFileRotation"
JVM_OPTS="$JVM_OPTS -XX:NumberOfGCLogFiles=10"
JVM_OPTS="$JVM_OPTS -XX:GCLogFileSize=10M"
#CassandraSummit 2014

73. Garbage Collection
Could be its own talk
Honorable mentions:
● https://github.com/chewiebug/GCViewer
● http://jworks.idv.tw/GcWeb/
● Python, R, Octave
#CassandraSummit 2014

74. Logging
/var/log/cassandra/system.log
o provides a rolling log
o log4j
/var/log/cassandra/output.log
o captured standard error and standard out
o truncated on restart
#CassandraSummit 2014
System Logs
o syslog, dmesg, etc

75. OS Metrics
#CassandraSummit 2014
Shout-out:
http://www.brendangregg.com/linuxperf.html

76. JVM
#CassandraSummit 2014
● Heap
o GC logs
o JMX
● Threads
o jvmtop
o Jstack (+htop)
o kill -3
o JMX

77. And Everything
#CassandraSummit 2014

78. Questions
?
#CassandraSummit 2014