Solr 8.11.1 Installation Type 3 with ZooKeeper



As CLAIMS Direct Solr is a pre-configured, bundled distribution of Apache Solr, it can be deployed on any number of nodes (individual instances). A group of nodes function to expose a collection. Further, multiple collections could be searched across the distribution.

There are many scenarios for a CLAIMS Direct deployment that range from indexing the entire content of CLAIMS Direct XML to the sparse indexing of certain fields and ranges of publication dates for application-specific usage. There could also be specific QoS requirements: minimum supported queries per second, average response time et al. All of these factors play a role in planning for a CLAIMS Direct Solr deployment. Generally speaking, a full index with the entire content of CLAIMS Direct XML requires, at a minimum:


Solr search server

nodes 1-3 housing the ZooKeeper quorum

  • CPU: 2 cores
  • RAM: 16GB
  • Disk: 1TB
1processing serverminimum:
  • CPU: 4 cores
  • RAM: 16GB
  • Disk: 250GB

The ZooKeeper quorum could be placed together on Solr search servers or, optionally, you could break out the ZooKeeper configuration into an additional 3 separate servers.

3ZooKeeper configuration serverminimum:
  • CPU: 1 core
  • RAM: 2GB
  • Disk: 50GB

The following diagram represents the minimum architecture required to support a full CLAIMS Direct index.

Primary Architecture

Unlike the PostgreSQL data warehouse, IFI CLAIMS does not provide a back file for Solr. All indexing is self-contained on-site.


All CLAIMS Direct software is to be installed from the applicable repository.

Installing ZooKeeper

sudo yum install alexandria-solr-zookeeper

alexandria-solr-zookeeper comes pre-configured to support up to a 5-node ZooKeeper quorum. You should install the alexandria-solr-zookeeper on at least 3 nodes.

Configuring ZooKeeper

The main configuration file for ZooKeeper can be found as /opt/alexandria/zookeeper/conf/zoo.cfg. For each node, the dataDir  and server entries need to reflect the node number and quorum members respectively.

Your IP addresses may be different.


The format of the server entry is as follows:

  • server.x 
    x being the node number. This corresponds to a myid file located under dataDir for each node.
  • IP address
    The IP address of the node
  • Port 1
    Port to connect followers to the leader
  • Port 2
    Port is used for leader election

The ports should not be changed.

A typical configuration for a 3-node quorum follows.

Node 1

# ...

Node 2

# ...

Node 3

# ...

Enable and Start ZooKeeper

The following should be done on all ZooKeeper nodes.

# enable automatic startup
sudo systemctl enable alexandria-solr-zookeeper

# start service
sudo systemctl start alexandria-solr-zookeeper

# check status
sudo systemctl status alexandria-solr-zookeeper

Installing SolrCloud

On all Solr nodes:

sudo yum install alexandria-solr-cloud

Data Directory

alexandria-solr-cloud collections reside under /var/lib/alexandria/solr-data. Collection sizes vary depending on the subscription level, number of nodes, shards etc. as defined below. A typical Premium Plus index, e.g., will initially be 8TB. The following table provides minimum and recommended disk requirements:

Number of NodesMinimumRecommended

Configuring SolrCloud

The following table lists the applicable nodes and their functions in a typical 8-node environment:

Description * Solr/ZooKeeperbasic Solr node with ZooKeeper * Solr/ZooKeeperbasic Solr node with ZooKeeper * Solr/ZooKeeperbasic Solr node with ZooKeeper * Solrbasic Solr node * Solrbasic Solr node * Solrbasic Solr node * Solrbasic Solr node * Solrbasic Solr node

Initial Template Node

On node-1, edit /opt/alexandria/solr/etc/solr-alexandria-vars. 

ALEXANDRIA_SOLR_CLOUD 1Run Solr in cloud mode. A value of 0 will run Solr in standalone mode.

The number of shards for a complete alexandria collection. This should correspond to the number of nodes in the cluster divided by the replication factor.


The IP addresses of each node. Note: this should be one line in the configuration.



The number of replicas per shard.



This limits the number of shards on a single node to 1.


The designated host to receive administrative commands: collection creation, status etc. This can be any node in the cluster.
ALEXANDRIA_SOLR_JVM_MEM8gThis is the Java heap setting. This should be at least 8G. Generally, 50-60% of total RAM should be allocated.
ALEXANDRIA_SOLR_ZK_NODES,, IP addresses of each member of the ZooKeeper quorum.
ALEXANDRIA_SOLR_ZK_HOST designated host to receive ZooKeeper administrative commands. This could be any member of the ZooKeeper quorum.

A note about nodes, shards and replication

In a typical SolrCloud cluster, redundancy and performance are achieved by distributing or sharding an index. How one distributes the shards across the available live nodes is critical. The above configuration creates 4 shards and 4 replicas spread over 8 nodes. Solr is smart enough to distribute these correctly. The above 4x2 cluster is a minimal configuration. A more performant cluster could have 8x2 (16 nodes) or, as CLAIMS Direct Search API, 16x2 (32 nodes).

Enable and Start Solr

The following should be done on all Solr nodes.

# enable automatic startup
systemctl enable alexandria-solr-cloud

# start service
systemctl status alexandria-solr-cloud

# check status
systemctl status alexandria-solr-cloud

Viewing Solr and ZooKeeper Status

After starting ZooKeeper and Solr, you can visit the internal Solr web page: Under Cloud → Nodes all available nodes should be visible as well as Cloud → ZK Status showing all ZooKeepers.

Bootstrapping the ZooKeeper Quorum

On the template node (node-1):

cd /opt/alexandria/solr/

# upload Solr configuration files
 Bootstrapping ...
  -> name: acdidx-v3.0.0
  -> directory: /var/lib/alexandria/solr-data/conf

Creating the Solr alexandria Collection

cd /opt/alexandria/solr/

# Create the alexandria collection
./bin/alexandria-solr-cloud-admin alexandria
Creating (action=CREATE) on ...
  -> name=alexandria
  -> numShards=8
  -> replicationFactor=2
  -> maxShardsPerNode=1
  -> collection.config=acdidx-v3.0.0
  -> property.config=solrconfig-alexandria.xml
Next Steps

Once Solr has been installed, set up the indexing daemon aidxd.