Monitor some of the things

2013-10-18
MONITOR
SOME OF THE THINGS

Optimization, Backups,
Replication, and more
3rd Edition
Covers Version 5.5
High
Performance
MySQL
Baron Schwartz,
Peter Zaitsev &
Vadim Tkachenko
ME
• Cofounder of @VividCortex
• Author of High Performance MySQL
• @xaprb on Twitter
• baron@vividcortex.com
• http://www.linkedin.com/in/xaprb

RANT, RECAPPED
• The sky is falling
• Tools drive processes, and we need better tools designed for methods
• Pay attention to CAPS (Capacity, Availability, Performance, Scalability)
• Monitoring tools need to be a lot smarter
• Measure and monitor “work getting done”

HARD CAPACITY
• Disk volume
• CPU Cycles
• max_connections
• File descriptors, sockets, TCP port
numbers, etc
• %used, absolute quantity available

SOFT CAPACITY
• Neil Gunther’s Universal Scalability
Law
• Throughput, concurrency, errors

AVAILABILITY
• Availability is absence of downtime • %used, absolute quantity available
• MTBF, MTTR, MTTD, %availability

TASK PERFORMANCE
• Task performance is consistently fast
response time.
• Measure an SLA in percentile
response time per task, over
observation intervals
• Response time, 95% response time

RESOURCE PERFORMANCE
• Resource performance is ability to run
tasks consistently fast.
• Throughput, concurrency, busy time,
total response time, backlog/queue

SCALABILITY
• Universal Scalability Law again • %used, absolute quantity available

STALL DETECTION
• Overloaded or underperforming? • %used, absolute quantity available
• Utilization, saturation, errors, sources
of load/demand

GIT ‘ER DONE
MONITOR WORK AND
RESOURCES

WHAT NOT TO DO
• Don’t use top-N lists from Google
• Don’t just do what’s included in some
Nagios plugin

№1
TOP 10 LIST
1. MySQL availability
2. Presence of insecure users and databases
3. Aborted connects
4. Error log
5. Deadlocks
6. Change in server configuration
7. Slow query log
8. Slave lag
9. Percentage of maximum allowed connections
10. Percentage of full table scans

№2
TOP 10 LIST
1. Threads_connected
2. Created_tmp_disk_tables
3. Handler_read_first
4. Innodb_buffer_pool_wait_free
5. Key_reads
6. Max_used_connections
7. Open_tables
8. Select_full_join
9. Slow_queries
10. Uptime

№1
PLUGIN
1. threadcache-hitrate (Hit rate of the thread-cache)
2. slave-io-running (Slave io running: Yes)
3. slave-sql-running (Slave sql running: Yes)
4. qcache-hitrate (Query cache hitrate)
5. qcache-lowmem-prunes (Query cache entries pruned because of low memory)
6. keycache-hitrate (MyISAM key cache hitrate)
7. bufferpool-hitrate (InnoDB buffer pool hitrate)
8. bufferpool-wait-free (InnoDB buffer pool waits for clean page available)
9. log-waits (InnoDB log waits because of a too small log buffer)
10. tablecache-hitrate (Table cache hitrate)
11. table-lock-contention (Table lock contention)
12. index-usage (Usage of indices)
13. tmp-disk-tables (Percent of temp tables created on disk)
14. long-running-procs (long running processes)

№2
PLUGIN
1. connection-time
2. uptime
3. threads-connected
4. threadcache-hitrate
5. q[uery]cache-hitrate
6. q[uery]cache-lowmem-prunes
7. [myisam-]keycache-hitrate
8. [innodb-]bufferpool-hitrate
9. [innodb-]bufferpool-wait-free
10. [innodb-]log-waits
11. tablecache-hitrate
12. table-lock-contention
13. index-usage
14. tmp-disk-tables
15. slow-queries
16. long-running-procs
17. slave-lag
18. slave-io-running
19. slave-sql-running
20. sql
21. open-files
22. encode
23. cluster-ndb-running

HTTP://WWW.FLICKR.COM/PHOTOS/NASAMARSHALL/5926864640/
SURFACE AREA

DUPLICATE SIGNALS
• Queries
• Com_admin_commands
• Com_assign_to_keycache
• Com_alter_db
• Com_alter_db_upgrade
• Com_alter_event
• Com_alter_function
• Com_alter_procedure
• Com_alter_server
• Com_alter_table
• Com_alter_tablespace
• Com_alter_user
• Com_analyze
• Com_begin
• Com_binlog
• Com_ad_nauseum

DESIRABLE METRICS
• Throughput, concurrency, busy time, total response time, backlog/queue
• Utilization, saturation, errors, sources of load/demand

RESOURCE LIMITS
• Threads_connected near max_connections?
• %table cache used?
• Open file handles?
• Long-running queries/transactions?

ERRORS
• Deadlocks?
• Aborted connects?

AVAILABILITY
• Ability to connect and run a query?
• Uptime is small?
• Replication is running?

PERFORMANCE
• You can get throughput (Queries) and concurrency (Threads_running) from MySQL
• But in a Nagios check, no context to know whether they’re good or bad
• You generally can’t get response time, busy time, utilization, backlog, etc
• You can aggregate thread states, thread times, users, databases, query abstracts...

NAGIOS IS BEST AT
LIVING IN THE
MOMENT

THOU SHALT NOT
• Cache hit ratios
• Thread cache hit ratio
• Buffer pool cache hit ratio
• Table cache hit ratio
• Key cache hit ratio
• Query cache hit ratio
• Rates of “bad” queries
• % temp tables on disk
• % full table scans
• % slow queries
• Unfixable things
• Replication delay

WHY NOT?
• Those are properties of the workload and application
• They are not conditions to alert/warn about
• They are not fixable / actionable in the service

№1 ALERT!!!!!
Disk CRIT 100% /dev/sda2

№2 ALERT!!!!!
Replication CRIT Slave I/O Thread No

№3 ALERT!!!!!
Replication CRIT Slave SQL Thread No

№4 ALERT!!!!!
Replication CRIT Seconds_Behind_Master NULL

№5 ALERT!!!!!
MySQL CRIT oldest transaction: 86400 seconds

№1 ALERT!!!!!
CRIT
* Disk /dev/sda2 full
* Replication stopped
* Oldest transaction 86400 seconds
* 4999 threads in status “Waiting for table metadata lock”

HOLLER AT ME
QUESTIONS?
@XAPRB / BARON@VIVIDCORTEX.COM

RESOURCES
• Chapter 3 of High Performance MySQL, 3rd Edition
• Percona White Papers
• Causes of Downtime in Production MySQL Servers
• Preventing MySQL Emergencies
• Goal-Driven Performance Optimization
• Forecasting MySQL Scalability with the Universal Scalability Law
• Method R: Optimizing Oracle Performance, Cary Millsap
• The Goal, Eli Goldratt
• The USE Method (Brendan Gregg) & his new book
• Guerrilla Capacity Planning, Neil J. Gunther
• Fundamental Performance & Scalability Instrumentation

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