Cisco Catalyst SD-WAN AppQoE Configuration Guide, Release 26.x and Later

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Cisco Catalyst SD-WAN AppQoE Configuration Guide, Release 26.x and Later

Reuse a DRE SSD after router chassis replacement

Updated: March 10, 2026

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Provides the wrapper topic for reusing a Data Redundancy Elimination solid-state drive after router chassis replacement.

You can install the Data Redundancy Elimination (DRE) solid-state drive (SSD) from a replaced router chassis in a replacement chassis. During startup, DRE examines the cache and metadata on the SSD to determine whether the existing cache can be used.

DRE does not restore connections or connection state from the previous chassis. After initialization, it establishes a new local identity and creates new connections as traffic arrives.

DRE cache behavior after router chassis replacement

DRE evaluates the hardware identity, software compatibility, DRE profile, cache layout, metadata, and disk encryption information during initialization.

While DRE initializes, traffic follows the configured bypass or service-failure behavior. Optimization efficiency can be lower until initialization completes and the cache is repopulated.

Cache condition

DRE behavior

What to expect

The cache format, disk layout, and encryption information are compatible.

DRE may load and re-index reusable cache content.

New connections are established after DRE becomes operational. Connections from the previous chassis are not restored.

The Cisco IOS XE release or DRE profile requires a different cache allocation.

DRE may resize the cache. If the cache size is reduced, DRE can remove older cached data.

Initialization can take longer than a normal startup.

DRE cannot recover the encryption information associated with the existing cache.

DRE should invalidate the existing cache, create new encryption information, and initialize an empty cache.

Cache utilization and the optimization ratio are initially low.

The cache format, metadata, or disk layout is incompatible or corrupted.

DRE should reset the cache and create a new cache.

DRE rebuilds the cache as it processes new traffic.

While DRE initializes, traffic follows the configured bypass or service-failure behavior. Optimization efficiency can be lower until initialization completes and the cache is repopulated.

Verify DRE Initialization

After the replacement chassis starts, verify that it detects the SSD and that the DRE container is running:

Device# show inventory
Device# show file systems
Device# show app-hosting list
Device# show app-hosting detail appid <dre-app-id>

Refer to Verify and Monitor and Troubleshoot DRE Using CLI to verify DRE health and cache status.

Review recent DRE errors, active flows, and system messages:

Device# show sdwan appqoe error recent
Device# show sdwan appqoe flow active
Device# show logging

Confirm the following:

  • The SSD is present and has the expected capacity.

  • The DRE container state is RUNNING.

  • DRE health status is GREEN.

  • DRE cache status is Active.

  • No disk, file-system, encryption, or cache-initialization alarms are active.

  • Before test traffic is generated, the number of current connections can be 0.

If DRE reset the cache, a cache utilization value of 0 percent or a low value is expected immediately after initialization. Generate traffic and confirm that new DRE connections are created and cache utilization begins to increase.

Recover DRE when initialization fails

Use this procedure only if DRE does not reach the GREEN health state with an Active cache after the existing SSD is installed.

A persistent initialization failure can indicate a problem with SSD detection or compatibility, cache resizing, cache metadata, encryption-key recovery, file-system access, disk capacity or health, or the DRE container installation.

Before you begin

  • Drain or redirect production traffic. Clearing the cache restarts the DRE service, and reinstalling the container temporarily removes the service.

  • Confirm that the replacement platform supports DRE. See Supported Devices for DRE.

  • Confirm that the SSD capacity meets the requirements of the DRE profile on the replacement chassis. See Supported DRE PrSupported DRE profilesofiles and Disk Recommendations for DRE.

  • If the replacement chassis uses a different Cisco IOS XE release or DRE profile, allow additional time for DRE to evaluate or resize the cache.

Procedure

  1. Before changing the cache or container, collect the following command output:

    Device# show app-hosting list
Device# show app-hosting detail appid <dre-app-id>
Device# show sdwan appqoe status
Device# show sdwan appqoe dreopt status detail
Device# show sdwan appqoe dreopt statistics detail
Device# show sdwan appqoe error recent
Device# show logging

    Also record the following information:

    • DRE application ID and package name and version

    • DRE package profile and application resource allocation

    • VirtualPortGroup and guest IP address configuration

    • Cisco IOS XE release

    • SSD capacity and file-system status

  2. If the DRE service is responsive, clear the DRE cache as described in Troubleshoot DRE.

    Clearing the cache removes the existing optimization data and restarts the DRE service. It does not restore connections from the previous chassis.

  3. Verify the DRE status again.

    If the health status is GREEN and the cache status is Active, no further recovery action is required.

  4. If clearing the cache does not recover DRE, reinstall the DRE container.

    • For CLI-managed installations, follow Uninstall DRE, Install DRE Container Package, and Activate DRE Service.

    • For devices managed by Cisco SD-WAN Manager, use the applicable device template, configuration group, or software-management workflow.

    • Install the DRE package that matches the Cisco IOS XE release running on the replacement chassis.

    • Restore the DRE profile, VirtualPortGroup mapping, guest IP address, and application resource allocation.

    Do not manually delete DRE files from the SSD.

  5. After reinstalling the container, generate test traffic and confirm the following:

    • The container state is RUNNING.

    • DRE health status is GREEN.

    • DRE cache status is Active.

    • No alarms are active.

    • New DRE connections are created.

    • Original-byte and optimized-byte counters increase.

    • Cache utilization begins to increase.

    • Connection initialization and reset counters do not increase unexpectedly.

What to do next

If DRE does not recover after container reinstallation, retain the diagnostic information and contact Cisco Technical Support.

DRE SSD reuse service impact

Reusing the SSD does not preserve active connections from the previous chassis.

Service impact

Clearing the cache or reinstalling the DRE container also removes the existing optimization state.

During initialization or recovery, DRE optimization can be temporarily unavailable. Traffic handling depends on the configured bypass or service-failure behavior. Clearing the cache or reinstalling the DRE container leaves the cache empty. Optimization efficiency increases gradually as new traffic repopulates the cache.