New Features in SharePoint 2013 – Part 3 (Cache Service)


Distributed Cache

Data-driven applications have become increasingly prevalent as data is consumed from more diverse sources, such as business applications, syndicated feeds, and social contexts. SharePoint Server 2013 Preview includes a new Distributed Cache Service built on the reliability of Windows Server AppFabric Distributed Caching. Distributed caching helps to ensure that no request takes too long.

So, coming to our questions how is this Distribution Cache setup?, What is the logic behind it? To understand it, we shall get deeper into it in the below topics.

  • Windows Server AppFabric extends Windows Server to provide enhanced hosting, management, and caching capabilities for Web applications and middle-tier services. The AppFabric hosting features add service management extensions to Internet Information Services (IIS), Windows Process Activation Service (WAS), and the .NET Framework 4. This includes Hosting Services and Hosting Administration tools that make it easier to deploy, configure, and manage Windows Communication Foundation (WCF) and Windows Workflow Foundation (WF) based services. The AppFabric caching features add a distributed, in-memory object cache to Windows Server that makes it easier to scale out high-performance .NET applications, especially ASP.NET applications.

  • How do you start Distributed Cache?

    The distributed cache feature is enabled by default and the distributed cache service is automatically started on all web and application servers in a farm. A new Windows service – the AppFabric Caching Service – is installed on each server in the farm when SharePoint is installed. It is managed via the Services on Server page in central admin as the “Distributed Cache” service and SharePoint_Config DB keeps track of which machines in the farm are running the cache service. In very large environments distributed cache can be offloaded to dedicated server.

  • How does it improve performance?

    Distributed Caching improves performance by

    • Caching My Site social data, such as news feeds,
    • Caching authentication tokens,
    • Workflows

       

  • Distributed Caching has its limitations
    • SharePoint 2013 uses caching features that cloud-based cache (Windows Azure Cache) does not support at this time, so only local cache hosts can be used; may change in the future
    • SharePoint ONLY supports the version of caching that it ships – you cannot independently upgrade it.

       

  • Service Account Requirements for Distributed Cache:
    • The farm account is used as service account for Cache Service
    • Like user profile service in SharePoint 2010, during setup the service account should have elevated privileges (i.e. local admin)
    • After setup is complete you should lower the privileges for the account

       

  • Cache Architecture:
    • For caching in farm, scale points have not been determined yet
    • How many servers are needed, what resources should be built out (CPU, memory, etc.)
    • More data will be available after Beta 2

       

  • Cache Physical Architecture:

     

  • Cache Server Performance:

    There are hundred(s) of performance counters that are exposed via developer’s dashboard. These counters can help in determining whether we need additional Cache Servers, CPU, or increase in the size of the memory, higher through put i/o, better disks, etc. Some of the performance counters that are important for Cache server performance are

    • Number of reads, number of writes, number of hits and number of misses
    • Time to read, time to write
    • Total I/O (how much data has been transferred in a given period of time)

       

  • Cache Service Health

    The following health rules have been created to help you track the Cache Service. Most of these health rules are present in Availability section.

    Availability:

    • One of the cache hosts in the cluster is down. We might have to restart the service on this box
    • Cache host is in throttled state. Which means we have availability issues, we may need to restart it
    • The high availability node for SharePoint distributed cache is not available – happens when there are less than 2 servers running the cache service

       

    Configuration:

    • Firewall client settings on the cache host are incorrect. Which means the Cache Host can’t be contacted
    • There exists at least one cache host in the cluster, which SP doesn’t know about – happens when the cache service is disabled in SharePoint but AppFabric Caching Service is running on the machine
    • Cached objects have been evicted – indicates eviction happened across the cache cluster. Not bad in and of itself but may be a clue if it happens frequently and/or there are performance issues

Come back soon to learn about New features in SharePoint 2013 – Part 4 (Request Management)

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About Vamshideep

SharePoint Architect
This entry was posted in SharePoint 2013. Bookmark the permalink.

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