Chapter 16. Creating caches with Data Grid Operator
Use Cache CRs to add cache configuration with Data Grid Operator and control how Data Grid stores your data.
16.1. Data Grid caches
Cache configuration defines the characteristics and features of the data store and must be valid with the Data Grid schema. Data Grid recommends creating standalone files in XML or JSON format that define your cache configuration. You should separate Data Grid configuration from application code for easier validation and to avoid the situation where you need to maintain XML snippets in Java or some other client language.
To create caches with Data Grid clusters running on OpenShift, you should:
-
Use
CacheCR as the mechanism for creating caches through the OpenShift front end. -
Use
BatchCR to create multiple caches at a time from standalone configuration files. - Access Data Grid Console and create caches in XML or JSON format.
You can use Hot Rod or HTTP clients but Data Grid recommends Cache CR or Batch CR unless your specific use case requires programmatic remote cache creation.
Cache CRs
-
CacheCRs apply to Data Grid service pods only. -
Each
CacheCR corresponds to a single cache on the Data Grid cluster.
16.2. Creating caches with the Cache CR
Complete the following steps to create caches on Data Grid service clusters using valid configuration in XML or YAML format.
Procedure
-
Create a
CacheCR with a unique value in themetadata.namefield. -
Specify the target Data Grid cluster with the
spec.clusterNamefield. Name your cache with the
spec.namefield.NoteThe
nameattribute in the cache configuration does not take effect. If you do not specify a name with thespec.namefield then the cache uses the value of themetadata.namefield.-
Add a cache configuration with the
spec.templatefield. Apply the
CacheCR, for example:oc apply -f mycache.yaml cache.infinispan.org/mycachedefinition created
Cache CR examples
XML
apiVersion: infinispan.org/v2alpha1 kind: Cache metadata: name: mycachedefinition spec: clusterName: infinispan name: myXMLcache template: <distributed-cache mode="SYNC" statistics="true"><encoding media-type="application/x-protostream"/><persistence><file-store/></persistence></distributed-cache>
YAML
apiVersion: infinispan.org/v2alpha1
kind: Cache
metadata:
name: mycachedefinition
spec:
clusterName: infinispan
name: myYAMLcache
template: |-
distributedCache:
mode: "SYNC"
owners: "2"
statistics: "true"
encoding:
mediaType: "application/x-protostream"
persistence:
fileStore: ~
16.3. Updating caches with the Cache CR
You can control how Data Grid Operator handles modifications to the cache configuration in the Cache CR.
Data Grid Operator attempts to update the cache configuration on the Data Grid Server at runtime. If the update fails, Data Grid Operator uses one of the following strategies:
- retain strategy
-
The Operator updates the status of the
CacheCR toReady=False. You can manually delete theCacheCR and create a new cache configuration. This is the default strategy. - recreate strategy
The Operator deletes the cache from the Data Grid cluster and creates a new cache with the latest
spec.templatevalue from theCacheCR.ImportantConfigure the
recreatestrategy only if your deployment can tolerate data loss.
Prerequisites
-
Have a valid
CacheCR.
Procedure
Use the
spec.updates.strategyfield to set theCacheCR strategy.mycache.yaml
spec: updates: strategy: recreateApply changes to the
CacheCR, for example:oc apply -f mycache.yaml
16.4. Adding persistent cache stores
You can add persistent cache stores to Data Grid service pods to save data to the persistent volume.
Data Grid creates a Single File cache store, .dat file, in the /opt/infinispan/server/data directory.
Procedure
Add the
<file-store/>element to thepersistenceconfiguration in your Data Grid cache, as in the following example:<distributed-cache name="persistent-cache" mode="SYNC"> <encoding media-type="application/x-protostream"/> <persistence> <file-store/> </persistence> </distributed-cache>
16.5. Adding caches to Cache service pods
Cache service pods include a default cache configuration with recommended settings. This default cache lets you start using Data Grid without the need to create caches.
Because the default cache provides recommended settings, you should create caches only as copies of the default. If you want multiple custom caches you should create Data Grid service pods instead of Cache service pods.
Procedure
- Access the Data Grid Console and provide a copy of the default configuration in XML or JSON format.
Use the Data Grid CLI to create a copy from the default cache as follows:
[//containers/default]> create cache --template=default mycache
16.5.1. Default cache configuration
This topic describes default cache configuration for Cache service pods.
<distributed-cache name="default"
mode="SYNC"
owners="2">
<memory storage="OFF_HEAP"
max-size="<maximum_size_in_bytes>"
when-full="REMOVE" />
<partition-handling when-split="ALLOW_READ_WRITES"
merge-policy="REMOVE_ALL"/>
</distributed-cache>Default caches:
- Use synchronous distribution to store data across the cluster.
- Create two replicas of each entry on the cluster.
- Store cache entries as bytes in native memory (off-heap).
- Define the maximum size for the data container in bytes. Data Grid Operator calculates the maximum size when it creates pods.
- Evict cache entries to control the size of the data container. You can enable automatic scaling so that Data Grid Operator adds pods when memory usage increases instead of removing entries.
- Use a conflict resolution strategy that allows read and write operations for cache entries, even if segment owners are in different partitions.
- Specify a merge policy that removes entries from the cache when Data Grid detects conflicts.
