ContextQMD
Back to Garnet

Frequently Asked Questions

website/docs/azure/faq.md

1.1.66.2 KB
Original Source

Frequently Asked Questions

General Questions

What is Azure Cosmos DB Garnet Cache?

Azure Cosmos DB Garnet Cache is a fully managed, high-performance caching service built on the Garnet remote cache-store from Microsoft Research. It provides Redis protocol compatibility with ultra-low latency and enterprise-grade security, scalability, and reliability.

How can I access the Preview?

Azure Cosmos DB Garnet Cache is currently in an expanded Private Preview. Please register your subscription to join the preview.

How is it different from self-hosted Garnet?

As a fully managed service, Azure Cosmos DB Garnet Cache handles infrastructure provisioning, scaling, patching, and monitoring automatically. Self-hosted Garnet requires you to manage the infrastructure, updates, and operations yourself.

How does it work with Azure Cosmos DB?

Azure Cosmos DB Garnet Cache works alongside Azure Cosmos DB to reduce latency for frequently accessed data. Your application manages the integration including checking the cache before reading from Azure Cosmos DB, and updating or invalidating cached entries after writing to Azure Cosmos DB. You control when to update or invalidate cached data to maintain consistency.

Is it compatible with Redis clients?

Yes, Azure Cosmos DB Garnet Cache uses the Redis RESP protocol, making it compatible with existing Redis clients in all major programming languages without code changes.

What Redis version is supported?

Azure Cosmos DB Garnet Cache supports the RESP protocol and doesn't have full support for any specific Redis version. Visit the list of supported Redis commands.

How is Azure Cosmos DB Garnet Cache priced?

Azure Cosmos DB Garnet Cache clusters are billed per instance per hour with no licensing fees. Each node will be billed for the chosen SKU plus an attached disk, used for data persistence, sized at 2x the total memory of each node. Pricing per SKU is set at different rates than the underlying Azure VM and is subject to change between our extended Private Preview and Public Preview.

For information about pricing for specific SKUs, reach out to [email protected].

Performance and Scalability

What performance can I expect?

Latency is typically sub-millisecond and is around 3ms at the 99th percentile. Performance and throughput varies by tier, key/ value size, and number of concurrent requests, among other factors.

Can I scale my cache?

Yes, you can scale out by adding shards, or scale up by changing SKU size within a VM family and generation with no downtime.

How many connections are supported?

Garnet doesn't limit the number of client connections that can be made on any node for any SKU. In practice, connection limits vary by SKU. See the virtual machine limits corresponding to the Azure Cosmos DB Garnet Cache SKU you choose.

Development and Integration

Which client libraries are supported?

All Redis client libraries are supported. Ensure you visit the list of supported commands. Popular libraries by language include:

Can I test it locally?

For local development, you can use the self-hosted Garnet server.

Regional Availability

Which regions is it available in?

Azure Cosmos DB Garnet Cache is available in many Azure regions. Check our supported regions list.

Which regions support Availability Zones?

Azure Cosmos DB Garnet Cache can be configured with availability zones during provisioning in supported Azure regions where there is capacity for your chosen SKU. See the list of Azure regions with availability zone support.

Troubleshooting

My application can't connect to the cache

Check these common issues:

  1. VNet configuration: Verify your client application is in the same virtual network as your cache.
  2. Authentication: Verify you've configured role based access control, which is required for data plane access. Role assignments can take several minutes to propagate after being created or modified.
  3. SSL/TLS: Ensure your client supports TLS.

Cache performance is slower than expected

Common causes and solutions:

  1. Connection pooling: Ensure proper connection pool configuration.
  2. Hot keys: Check for key access patterns causing bottlenecks.
  3. Memory pressure: Monitor memory usage and consider scaling up.
  4. Network latency: Test from the same region as your cache.

I'm getting timeout errors

Troubleshooting steps:

  1. Check timeout settings: Verify client timeout configuration.
  2. Monitor CPU/memory: High resource usage can cause timeouts.
  3. Network issues: Test network connectivity between client and cache.

Getting Help

Where can I get technical support?

  • Documentation: For conceptual guidance and tutorials
  • Azure Support: Create support tickets for technical issues
  • Community: Stack Overflow and Azure forums

How do I report bugs or request features?

  • Azure Support for bugs and critical issues
  • Feedback Form for feature requests or suggestions

Next Steps