11.7. Tuning the Undercloud
The advice in this section aims to help increase the performance of your Undercloud. Implement the recommendations as necessary.
- The OpenStack Authentication service (
keystone) uses a token-based system for access to other OpenStack services. After a certain period, the database accumulates many unused tokens. It is recommended you create a cronjob to flush the token table in the database. For example, to flush the token table at 4 a.m. each day:0 04 * * * /bin/keystone-manage token_flush
- Heat stores a copy of all template files in its database's
raw_templatetable each time you runopenstack overcloud deploy. Theraw_templatetable retains all past templates and grows in size. To remove unused templates in theraw_templatestable, create a daily cronjob that clears unused templates that exist in the database for longer than a day:0 04 * * * /bin/heat-manage purge_deleted -g days 1
- The
openstack-heat-engineandopenstack-heat-apiservices might consume too many resources at times. If so, setmax_resources_per_stack=-1in/etc/heat/heat.confand restart the heat services:$ sudo systemctl restart openstack-heat-engine openstack-heat-api
- Sometimes the director might not have enough resources to perform concurrent node provisioning. The default is 10 nodes at the same time. To reduce the number of concurrent nodes, set the
max_concurrent_buildsparameter in/etc/nova/nova.confto a value less than 10 and restart the nova services:$ sudo systemctl restart openstack-nova-api openstack-nova-scheduler
- Edit the
/etc/my.cnf.d/server.cnffile. Some recommended values to tune include:- max_connections
- Number of simultaneous connections to the database. The recommended value is 4096.
- innodb_additional_mem_pool_size
- The size in bytes of a memory pool the database uses to store data dictionary information and other internal data structures. The default is usually 8M and an ideal value is 20M for the Undercloud.
- innodb_buffer_pool_size
- The size in bytes of the buffer pool, the memory area where the database caches table and index data. The default is usually 128M and an ideal value is 1000M for the Undercloud.
- innodb_flush_log_at_trx_commit
- Controls the balance between strict ACID compliance for commit operations, and higher performance that is possible when commit-related I/O operations are rearranged and done in batches. Set to 1.
- innodb_lock_wait_timeout
- The length of time in seconds a database transaction waits for a row lock before giving up. Set to 50.
- innodb_max_purge_lag
- This variable controls how to delay INSERT, UPDATE, and DELETE operations when purge operations are lagging. Set to 10000.
- innodb_thread_concurrency
- The limit of concurrent operating system threads. Ideally, provide at least two threads for each CPU and disk resource. For example, if using a quad-core CPU and a single disk, use 10 threads.
- Ensure that heat has enough workers to perform an Overcloud creation. Usually, this depends on how many CPUs the Undercloud has. To manually set the number of workers, edit the
/etc/heat/heat.conffile, set thenum_engine_workersparameter to the number of workers you need (ideally 4), and restart the heat engine:$ sudo systemctl restart openstack-heat-engine
