Service Instance Resource Usage

On this page we will present the most important resource usage limits for our data services. If a property is specified as "-" there is no property in the BOSH release for that particular setting but we list it here in order to document the default setting for the the user's convenience.

For any setting not specified in the tables below, the value used by the a9s Data Service is identical to the default value for the specific version of the underlying data service. Please see the documentation for that data service in order to learn more.

a9s Parachute

All our service instances are monitored by the a9s Parachute in order to make sure the service will not continue to operate once a certain threshold has been reached in terms of disk space usage. For more information, see a9s Parachute

a9s LogMe 2

Documentation

Property	Setting	Default Value	Description
opensearch.java_maxmetaspace	-XX:MaxMetaspaceSize	512M	Java MaxMetaSpace Value in Megabyte
opensearch.java_heapspace	-Xms | -Xmx	46% of available memory	Heapsize for the Opensearch JVM

a9s MongoDB

Documentation

Property	Setting	Default Value	Description
-	net.maxIncomingConnections	65536	The maximum number of simultaneous connections that mongos or mongod will accept. This setting has no effect if it is higher than your operating system’s configured maximum connection tracking threshold.
-	storage.syncPeriodSecs	60	The amount of time (in seconds) that can pass before MongoDB flushes data to the data files via an fsync operation.
-	storage.wiredTiger.engineConfig.cacheSizeGB	50% of (RAM - 1 GB) but at least 256MB	The maximum size of the internal cache that WiredTiger will use for all data.
-	replication.oplogSizeMB	5% of available disk space.	The maximum size in megabytes for the replication operation log (i.e., the oplog).

a9s MariaDB

Documentation

Replace the <replace-me> value for:

• When it is an a9s MariaDB >= 10.6 use mariadb.
• When it is an a9s MariaDB < 10.6 use cf_mysql.mysql.

Property	Setting	Default Value	Description
<replace-me>.max_connections	max_connections	1500	The max. number of client connections per MariaDB node (calculated per node in a replicated setup)
<replace-me>.innodb_buffer_pool_size	innodb_buffer_pool_size	\<computed>	By default this 80% of available memory (see: innodb_buffer_pool_size_percent)
<replace-me>.innodb_buffer_pool_size_percent	innodb_buffer_pool_size_percent	80%	Set this to an integer (0-100) which represents the percentage of system RAM to reserve for InnoDB's buffer pool
<replace-me>.max_allowed_packet	max_allowed_packet	256M	The maximum size in bytes of a packet or a generated/intermediate string
<replace-me>.max_heap_table_size	max_heap_table_size	16777216	The maximum size (in rows) to which user-created MEMORY tables are permitted to grow
<replace-me>.tmp_table_size	tmp_table_size	33554432 (32M)	The maximum size (in bytes) of internal in-memory temporary tables
-	slow_query_log	ON	Whether slow queries should be logged (ON) or not (OFF).
<replace-me>.long_query_time	long_query_time	10	Threshold in seconds above which SQL queries get logged in the slow query log file

a9s PostgreSQL

Documentation

Property	Setting	Default Value	Description
postgresql-ha.plan.effective_cache_size (optional)	effective_cache_size (MB)	50% or 75% (if host RAM >=4GB) or min: 256MB	The planner's assumption about the effective size of the disk cache that is available to a single query.
postgresql-ha.plan.max_connections (optional)	max_connections	(${shared_buffers} / ${work_mem}) * 2 or min: 128	The maximum number of concurrent connections to the database server.
postgresql-ha.plan.shared_buffers (optional)	shared_buffers (Integer in MB)	25% or 15% (if host RAM <1GB) or min: 128 (Integer in MB)	The amount of memory the database server uses for shared memory buffers.
postgresql-ha.plan.temp_file_limit (optional)	temp_file_limit	-1	The maximum amount of disk space that a process can use for temporary files, such as sort and hash temporary files, or the storage file for a held cursor. The value is specified in kilobytes, and -1 (the default) means no limit.
postgresql-ha.plan.work_mem (optional)	work_mem (MB)	8MB	The amount of memory to be used by internal sort operations and hash tables before writing to temporary disk files. query.
postgresql-ha.plan.maintenance_work_mem (optional)	maintenance_work_mem (MB)	64MB	This is the max memory that an operation like VACCUM, adding indexes or foreign keys can consume.
postgresql-ha.continuous_archiving.archive_timeout (optional)	archive_timeout (seconds)	60	Force the server to switch to a new WAL segment file periodically limiting how old unarchived data can be. Can be 0, or any value higher than 60.

Examples

Here we give you examples for different service plans with values computed based on the VM in which the service instance runs. For that purprose, we define the service plan instances to have a given amount of RAM.

a9s PostgreSQL single small (RAM: 2GB)

Setting	Default Value	Description
effective_cache_size (MB)	1GB	The planner's assumption about the effective size of the disk cache that is available to a single query.
max_connections	256	The maximum number of concurrent connections to the database server.
shared_buffers (MB)	512MB	The amount of memory the database server uses for shared memory buffers.
temp_file_limit	-1	The maximum amount of disk space that a process can use for temporary files, such as sort and hash temporary files, or the storage file for a held cursor. The value is specified in kilobytes, and -1 (the default) means no limit.
work_mem (MB)	8MB	The amount of memory to be used by internal sort operations and hash tables before writing to temporary disk files. query.
maintenance_work_mem (MB)	64MB	This is the max memory that an operation like VACCUM, adding indexes or foreign keys can consume.

a9s PostgreSQL single big (RAM: 8GB)

Setting	Default Value	Description
effective_cache_size (MB)	6GB	The planner's assumption about the effective size of the disk cache that is available to a single query.
max_connections	512	The maximum number of concurrent connections to the database server.
shared_buffers (MB)	2048MB	The amount of memory the database server uses for shared memory buffers.
temp_file_limit	-1	The maximum amount of disk space that a process can use for temporary files, such as sort and hash temporary files, or the storage file for a held cursor. The value is specified in kilobytes, and -1 (the default) means no limit.
work_mem (MB)	8MB	The amount of memory to be used by internal sort operations and hash tables before writing to temporary disk files. query.
maintenance_work_mem (MB)	64MB	This is the max memory that an operation like VACCUM, adding indexes or foreign keys can consume.

a9s KeyValue

Documentation

Property	Setting	Default Value	Description
valkey.lua-time-limit	lua-time-limit	5000	Max execution time of a Lua script in milliseconds
valkey.maxclients	maxclients	10000	Max number of connected clients at the same time
valkey.maxmemory-policy	maxmemory-policy	volatile-lru	Eviction policy to use when maxmemory is reached. Options: volatile-lru, allkeys-lru, volatile-lfu, allkeys-lfu, volatile-random, allkeys-random, volatile-ttl, noeviction
valkey.maxmemory-samples	maxmemory-samples	5	Number of samples Valkey checks before deleting one
valkey.slowlog-log-slower-than	slowlog-log-slower-than	10000	Execution time to log commands slower than the given number in microseconds
valkey.slowlog-max-len	slowlog-max-len	128	Log length
valkey.tcp-backlog	tcp-backlog	10000	Queue length for established TCP connections
valkey.tcp-keepalive	tcp-keepalive	30	Period used to send TCP ACKs

a9s Messaging

Documentation

Property	Setting	Default Value	Description
-	ulimit -n	64000	The max. number of file descriptors the RabbitMQ process is allowed to open (unix specific)
-	async threads	+A 64	The max. number of async threads the Erlang VM will make available - see here for more information
-	vm_memory_calculation_strategy	rss	Selects Erlang VM memory consumption calculation strategy
rabbitmq.vm_memory_high_watermark	vm_memory_high_watermark.relative	0.42	Maximum memory in percent which RabbitMQ could use.
-	vm_memory_high_watermark_paging_ratio	0.5	Fraction of the high watermark limit at which queues start to page message out to disc in order to free up memory.
rabbitmq.disk_free_limit_mem_relative	disk_free_limit.relative	1.5	At least disk_free_limit_mem_relative*TOTAL_RAM must be available on disk - in case this limit is reached the broker will start blocking clients which publish messages
rabbitmq.tcp_listen_backlog	tcp_listen_options.backlog	2048	Maximum size of the unaccepted TCP connections queue. When this size is reached, new connections will be rejected.
-	tcp_listen_options.nodelay	true	Disable Nagle's Algorithm
rabbitmq.tcp_listen_backlog	tcp_listen_options.backlog	2048	Maximum size of the unaccepted TCP connections queue. When this size is reached, new connections will be rejected.
-	queue_index_embed_msgs_below	4096	Size in bytes below which to embed messages in the queue index

a9s Redis

Documentation

Property	Setting	Default Value	Description
redis.tcp-backlog	tcp-backlog	10000	Queue length for established TCP connections
redis.tcp-keepalive	tcp-keepalive	30	Period used to send TCP ACKs
redis.maxclients	maxclients	10000	Max. number of connected clients at the same time
redis.maxmemory-policy	maxmemory-policy	volatile-lru	Policy of what to remove when maxmemory is reached. Options: volatile-lru, allkeys-lru, volatile-lfu, allkeys-lfu, volatile-random, allkeys-random, volatile-ttl, noeviction
redis.maxmemory-samples	maxmemory-samples	5	Number of samples Redis checks before deleting one
redis.lua-time-limit	lua-time-limit	5000	Max execution time of a Lua script in milliseconds
redis.slowlog-log-slower-than	slowlog-log-slower-than	10000	Execution time to log commands slower than the given number in microseconds
redis.slowlog-max-len	slowlog-max-len	128	Log length