DHCP Server Performance Degradation: High CPU Utilization and Database Compaction (dhcp.mdb)

Hello @Lyn Lyn

Given the symptoms- high CPU, DHCP request backlog, JET errors, and dhcp.mdb contention, I'd investigate the DHCP database before assuming this is a CPU or hardware-capacity problem.

For Windows Server 2022, Microsoft still supports Jetpack.exe for compacting the DHCP database. The key point is that this is an offline operation: you must stop the DHCP Server service before running it.

I would schedule a maintenance window and first make a DHCP backup. Then:

net stop dhcpserver
cd %SystemRoot%\System32\dhcp
jetpack.exe dhcp.mdb tmp.mdb
net start dhcpserver

Make sure tmp.mdb doesn't already exist. Jetpack creates a temporary database, copies the database records into it, removes the original database, and replaces it with the compacted copy.

Before doing this, I'd also verify that you have a usable DHCP backup. Microsoft's DHCP APIs support backing up the server configuration, settings, and client lease database, which is particularly important before database maintenance.

However, 50,000 active leases alone shouldn't automatically require manual compaction. If the problem returns shortly after compaction, I'd investigate the underlying cause rather than repeatedly running Jetpack. In particular, check disk latency/queue depth on the volume containing %SystemRoot%\System32\dhcp, antivirus/EDR exclusions, available disk space, DHCP audit logs, and the DHCP Server/System event logs around Events 1014, 1016 and 1053.

Also check the configured database maintenance settings. Windows DHCP has configurable backup and cleanup intervals, and the DHCP database configuration exposes both BackupInterval and CleanupInterval.

If this DHCP server is production-critical, I'd also consider implementing DHCP failover before performing extended database maintenance so clients aren't dependent on a single DHCP instance.

I would not delete dhcp.mdb, JET logs, or manually replace database files while the DHCP service is running. If Jetpack itself returns a JET/database error, preserve the existing database and backup files and investigate database corruption before making further changes.

Sharing these references with you:

Microsoft Learn – Jetpack command

Microsoft Learn – DHCP database backup AP

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