+h3. Default request concurrency, new limit on log requests
+
+The configuration value @API.MaxConcurrentRequests@ (the number of concurrent requests that will be accepted by a single instance of arvados-controller) now has a default value of 64, instead of being unlimited.
+
+New configuration value @API.LogCreateRequestFraction@ (default 0.50) limits requests that post live container logs to the API server, to avoid situations where log messages crowd out other more important requests.
+
+h3. New limit on concurrent workflows
+
+New configuration options @CloudVMs.SupervisorFraction@ (default 0.30) limits the number of concurrent workflow supervisors, to avoid situations where too many workflow runners crowds out actual workers.
+
+h3. Default limit for cloud VM instances
+
+There is a new configuration entry @CloudVMs.MaxInstances@ (default 64) that limits the number of VMs the cloud dispatcher will run at a time. This may need to be adjusted to suit your anticipated workload.
+
+Using the obsolete configuration entry @MaxCloudVMs@, which was previously accepted in config files but not obeyed, will now result in a deprecation warning.
+
+h3. Slow migration on upgrade
+
+This upgrade includes a database schema update (changing an integer column in each table from 32-bit to 64-bit) that may be slow on a large installation. Expect the arvados-api-server package upgrade to take longer than usual.
+
+h2(#v2_5_0). v2.5.0 (2022-12-22)
+
+"previous: Upgrading to 2.4.4":#v2_4_4
+
+h3. Dispatchers require PostgreSQL database access
+
+All dispatchers (cloud, LSF, and Slurm) now connect directly to the PostgreSQL database. Make sure these connections are supported by your network firewall rules, PostgreSQL connection settings, and PostgreSQL server configuration (in @pg_hba.conf@) as shown in the "PostgreSQL install instructions":{{site.baseurl}}/install/install-postgresql.html.