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Microsoft Connected Cache for Enterprise and Education caching software is deployed to host machines as a container. The container OS and any software component within the container need to be updated to address security vulnerabilities and improve quality and performance. These Microsoft-published container updates are referred to as "Connected Cache updates" in this article.
Microsoft silently deploys Connected Cache updates to your cache nodes based on the Update Ring setting you configure for each cache node.
Update rings
Connected Cache nodes can be configured to either the Beta or Stable update ring. The Stable ring is the default and delivers validated container updates on a configurable schedule. The Beta ring is an opt-in preview ring that receives new container versions before they're ready for Stable release, providing early access to new features and improvements.
For example, you could enroll a test cache node in the Beta ring to gain early access to new features and validate that clients can successfully interact with the test cache node. This builds confidence that the update works in your environment before it reaches your production cache nodes on the Stable ring.
Update ring options
Note
After changing your cache node's update ring on the Updates tab, select Save to ensure that the new setting is applied.
Important
In the event of a critical security patch, Microsoft might initiate a Connected Cache update to your cache node as soon as possible, regardless of the update ring setting. Visit the Release notes page for a detailed changelog of each Connected Cache update.
Stable ring
All Connected Cache nodes are enrolled in the Stable ring by default. The Stable ring receives the latest stable container version, providing a reliable experience. You can configure the day of the week and time of day that your cache node receives new container versions. By default, the update day is set to Monday and the update time is set to 00:00 UTC. All update ring settings can be managed from the Azure portal or through the Azure CLI.
For example, if Microsoft releases a new Stable container version on Tuesday at 17:00 UTC and your cache node is configured to update on Mondays at 00:00 UTC, your cache node receives the new Stable container version the following Monday at 00:00 UTC.
| Setting | Description |
|---|---|
| Day of the week | Monday through Sunday can be selected. |
| Time of day | Time of day is based on UTC and a 24-hour clock. |
Beta ring
The Beta ring is an opt-in preview ring that receives new container versions before they're ready for Stable release. By enrolling your cache nodes in the Beta ring, you can gain early access to new features and improvements, but you might also encounter bugs or issues.
You can unenroll from the Beta ring and roll back your cache node to the latest Stable release by changing back to the Stable ring.
You can report issues and give feedback on Beta container versions at https://aka.ms/mcc-beta-feedback.
Updating Connected Cache Linux Components
As part of the Connected Cache installation process, there are several packages and kernel-level configurations that are installed and configured within the Connected Cache Linux environment to optimize delivery. If Connected Cache is deployed to a Linux host machine, these packages and configurations are made to the host machine itself. If Connected Cache is deployed to a Windows host machine, these packages and configurations are made to the Windows Subsystem for Linux (WSL) distribution.
These packages and kernel-level configuration may need to be updated for several reasons, such as security and compatibility. Note that while Connected Cache uses Azure IoT Edge as its container orchestration layer, this guidance is focused on the host-level implications and configurations.
Package Version Updates
The following packages are updated as part of Connected Cache lifecycle operations.
Azure IoT Edge and Identity Service Versions
Microsoft Connected Cache is deployed as an Azure IoT Edge module today and the IoT Edge runtime and associated identity services are updated to ensure compatibility with Microsoft Connected Cache container images.
Docker Server and Client Versions
Azure IoT Edge uses Moby-based Docker components (moby-engine, moby-cli) for container management. These are updated to maintain compatibility with the Azure IoT Edge infrastructure.
Kernel Network Configuration
The Microsoft Connected Cache installation modifies kernel-level configurations for performance tuning and updates to these configurations may be required to ensure efficient, performant delivery of content to your network.
The following kernel parameters are commonly tuned on Connected Cache Linux hosts to optimize network performance and container behavior:
- net.ipv4.tcp_congestion_control
- net.core.default_qdisc
- net.core.somaxconn
- net.ipv4.ip_local_port_range
- net.ipv4.tcp_rmem
- net.ipv4.tcp_wmem
- net.ipv4.tcp_mem
- net.netfilter.nf_conntrack_max
- net.nf_conntrack_max
- net.core.optmem_max
Cleanup of Old Docker Images
The update process includes cleanup of outdated or unused Docker images, including:
- edgeAgent
- edgeHub
- mcc
This ensures disk space is reclaimed and only current versions are retained.
Update process
When Microsoft publishes a Connected Cache update, the Connected Cache service attempts to update all Connected Cache nodes based on their Update Ring membership. If a cache node can't complete the silent Connected Cache update within 6 hours of starting, an error message is surfaced in the Azure portal.
Update terminology, criteria, and information
Connected Cache updates are released based on need instead of on a set cadence.
| Update type | Criteria and information |
|---|---|
| Security | Security updates are the highest priority and are released based on the severity rating of the vulnerability. Updates for Critical and High vulnerabilities are released by Microsoft within 60 days of discovery. Updates for Medium and Low vulnerabilities are released by Microsoft within 120 days. |
| Quality | Quality updates fix a specific problem and addresses a noncritical, non-security-related bug. Quality updates could include performance fixes for a specific problem or changes related to cache efficiency or maximum egress for example. Quality updates are released along with security updates or when necessary to ensure proper functioning of the Microsoft Connected Cache software. |
For information on all released Microsoft Connected Cache updates, see the Connected Cache release notes.