If your AEM Assets deployment uses FileDataStore (FDS) on a storage area network (SAN) or network-attached storage (NAS), multiple network calls between AEM Assets and the external storage during high-load conditions can reduce the efficiency of FDS and increase latency. Moreover, OAK indexes are stored within SAN/NAS and even an idle system performs numerous read operations on system-generated data.
To increase the efficiency of your FDS, a local file system cache is enabled in front of a SAN storage. When you upload an asset, AEM first looks up the binary in the local file system cache. If it doesn't find the binary, AEM fetches it from SAN. Caching reduces network traffic between AEM and SAN. This way, SAN latency is reduced, and the efficiency of FDS is improved.
This feature is helpful in deployment scenarios where FDS is mounted on NAS/SAN storage. It was implemented via OAK issue OAK-3253 for AEM 6.2 and then backported in hotfix 12817 for OAK 1.2.20 for AEM 6.1. To leverage the feature, install hotfix 12817 for OAK 1.2.20 or above on your AEM setup, and make the following configuration changes:
To enable caching, add the following configuration in the crx-quickstart\install folder:
- PID org.apache.jackrabbit.oak.plugins.blob.datastore.FileDataStore
- Review the following sample configuration.