2024-06-11 –, Palais Atelier
Modifying SolrCloud to separate compute and storage presents challenges but is cost effective and improves scalability and availability. Nodes become stateless and durability is delegated to the shared storage implementation.
Salesforce runs such clusters at scale. The code is open source.
The traditional architecture of a search cluster, with nodes providing compute and persistent storage, ends up being more expensive to run than it should, especially in the context of public cloud and when dealing with unpredictable traffic patterns/load.
This presentation is about modifying the implementation of SolrCloud so a single copy of each index is stored on shared storage (for example S3) and accessed by all nodes for reads and updates. The nodes are then stateless, which means any one (or all) of them can be turned off at any time without data loss. New nodes added to the cluster get their data from the shared storage and not from other nodes. Note that many aspects of this new architecture apply to other search clusters, and no prior knowledge of SolrCloud is assumed.
Such an approach is a good match for running Search on a public cloud infrastructure, as it allows for compute and storage to be scaled independently and decreases the overhead of bringing a new node up in the cluster.
The challenges faced in the process of separating compute and storage will be detailed. The hard problems concern updates (indexing), and protecting the shared storage from conflicting concurrent updates, preventing data loss or overwrites yet allowing concurrent updates. Tradeoffs for integrating such a large conceptual change into an existing system will also be discussed.
The existing code has limitations that will be presented, as well as a high level design and plans for lifting them.
The current code is available (see SIP-20 https://cwiki.apache.org/confluence/display/SOLR/SIP-20%3A+Separation+of+Compute+and+Storage+in+SolrCloud for code and documentation).
The aim is to eventually merge these changes into the main Solr branch.
Working on search architecture at Salesforce in Grenoble, France. Lucene/Solr committer.
Holding a business administration and computer science engineering degrees and a PhD in parallel computing.
Prior to Salesforce, worked at Intel, HP Labs in Palo Alto and EMC/Documentum among others. Long ago wrote the Apple II computer game “Saracen.”
When not in front of a screen I'm usually either drumming, biking in the Alps or paragliding above them.