Skip to main content

Azure Storage tiers and availability

By
In this post, we will cover what are the main differences between all the storage tiers available inside Azure Storage.
With the launch of Geo Zone Redundant Storage, there are 6 different types of tiers, that can cover different scenarios. Let's take on different scenarios and see which of them are most suitable for different cases.

Whare are the 6 different tiers?
  • Locally redundant storage (LRS)
  • Geo-redundant storage (GRS)
  • Read Access geo-redundant storage (RAGRS)
  • Zone-redundent storage (ZRS)
  • Geo Zone Redundant Storage (GZRS)
  • Read Access Geo Zone Redundant Storage (RAGZRS)
Remember that all of them are having an availability SLA to write access that has 3 nines (99.9%). The read SLA is different for each tier and starts from 99.9% for LRS, GRS, ZRS and GZRS and goes up to 99.99% for RAGRS and RAGZRS. The durability SLA for a year is at least 11 nines for LRS and goes up to 16 nines for GRS, RAGRS, GZRS and RAGZRS.

Scenario 1: One storage node is not available inside the Availability Zone
For all 6 storage tiers, this case is covered because there at least 3 replicas of the storage on different nodes. The unavailability of one storage node is not affecting access to the content.

Scenario 2: An Availability Zone is down
  • Locally redundant storage (LRS)
    • High impact, content is not available anymore as long as the Availability Zone is down
  • Geo-redundant storage (GRS) & Read Access geo-redundant storage (RAGRS)
    • Content is still available. 
    • Even so, a failover needs to be triggered to make content available in the secondary locations, that would become the primary one (DNS entries need to be updated)
    • To identify the real value behind the RPO the Last Sync Time property can be used.
    • Using Last Sync Time we can identify what data was lost
  • Zone-redundent storage (ZRS) & Geo Zone Redundant Storage (GZRS) & Read Access Geo Zone Redundant Storage (RAGZRS)
    • No impact, content is available and ready to be consumed
    • Content is available in different Availability Zones
Scenario 3: An entire region is not available
  • Locally redundant storage (LRS)
    • High impact, content is not available anymore. 
    • There are no replicas in other regions
  • Geo-redundant storage (GRS) & Read Access geo-redundant storage (RAGRS)
    • Content is still available
    • Failover needs to be triggered to make content available from the secondary region
    • Last Sync Time property can be used to identify what data was lost 
  • Zone-redundent storage (ZRS)
    • High impact, content is not available. All 3 replicas were done on different Availability Zones from the same region
  • Geo Zone Redundant Storage (GZRS) & Read Access Geo Zone Redundant Storage (RAGZRS)
    • In both cases the replicas in another region are available, but the manual trigger for the failover procedure needs to be done
    • For RAGZRS the secondary node already supports reads operations, but failover is required to support write operations

    What tier should I use?
    Deciding what type of tier to use is hard and it is all the time a tradeoff between costs and features. Beside this tiers, we have the access tiers (hot, cool and archive). Hard choice. 

    In the next post, we will take some real-life scenarios and we will indentify the most suitable tier.

    Comments

    Post a Comment

    Popular posts from this blog

    Windows Docker Containers can make WIN32 API calls, use COM and ASP.NET WebForms

    By
    After the last post , I received two interesting questions related to Docker and Windows. People were interested if we do Win32 API calls from a Docker container and if there is support for COM. WIN32 Support To test calls to WIN32 API, let’s try to populate SYSTEM_INFO class. [StructLayout(LayoutKind.Sequential)] public struct SYSTEM_INFO { public uint dwOemId; public uint dwPageSize; public uint lpMinimumApplicationAddress; public uint lpMaximumApplicationAddress; public uint dwActiveProcessorMask; public uint dwNumberOfProcessors; public uint dwProcessorType; public uint dwAllocationGranularity; public uint dwProcessorLevel; public uint dwProcessorRevision; } ... [DllImport("kernel32")] static extern void GetSystemInfo(ref SYSTEM_INFO pSI); ... SYSTEM_INFO pSI = new SYSTEM_INFO(...
    Post a Comment
    Read more

    How to audit an Azure Cosmos DB

    By
    In this post, we will talk about how we can audit an Azure Cosmos DB database. Before jumping into the problem let us define the business requirement: As an Administrator I want to be able to audit all changes that were done to specific collection inside my Azure Cosmos DB. The requirement is simple, but can be a little tricky to implement fully. First of all when you are using Azure Cosmos DB or any other storage solution there are 99% odds that you’ll have more than one system that writes data to it. This means that you have or not have control on the systems that are doing any create/update/delete operations. Solution 1: Diagnostic Logs Cosmos DB allows us activate diagnostics logs and stream the output a storage account for achieving to other systems like Event Hub or Log Analytics. This would allow us to have information related to who, when, what, response code and how the access operation to our Cosmos DB was done. Beside this there is a field that specifies what was th...
    Post a Comment
    Read more

    Cloud Myths: Cloud is Cheaper (Pill 1 of 5 / Cloud Pills)

    By
    Cloud Myths: Cloud is Cheaper (Pill 1 of 5 / Cloud Pills) The idea that moving to the cloud reduces the costs is a common misconception. The cloud infrastructure provides flexibility, scalability, and better CAPEX, but it does not guarantee lower costs without proper optimisation and management of the cloud services and infrastructure. Idle and unused resources, overprovisioning, oversize databases, and unnecessary data transfer can increase running costs. The regional pricing mode, multi-cloud complexity, and cost variety add extra complexity to the cost function. Cloud adoption without a cost governance strategy can result in unexpected expenses. Improper usage, combined with a pay-as-you-go model, can result in a nightmare for business stakeholders who cannot track and manage the monthly costs. Cloud-native services such as AI services, managed databases, and analytics platforms are powerful, provide out-of-the-shelve capabilities, and increase business agility and innovation. H...
    Post a Comment
    Read more