Wednesday, September 18, 2013

Windows Azure storage concepts

You can create a storage accounts in windows Azure and provide your applications access to the tables, Blobs and queues in it.

  • The maximum capacity of data for storage accounts is 200TB, if it was created after June 8th 2012 and 100 TB if created before that.
  • Geo redundant Storage(GRS): Replicates the storage to a secondary, geographically separate location. Data is replicated asynchronously to the secondary location in the background. If there is any failure in primary location, storage will failover to the secondary location
  • Locally redundant Storage(LRS) : For any storage, the data is replicated three times within the same datacentre. All Windows Azure storages are locally redundant
  • Affinity group: It is a geographical grouping of cloud deployments and storage accounts.By grouping the services used by your application in a affinity group in  a particular geographical location, you can improve your service performance
  • Storage account endpoints: Highest namespace for accessing the tables, queues and blobs in a storage. Default endpoints will have the following values
Blob service: http://mystorageaccount.blob.core.windows.net
Table service: http://mystorageaccount.table.core.windows.net
Queue service: http://mystorageaccount.queue.core.windows.net


  • Storage account URLS: URls for accessing an object in a storage account For eg: http://mystorageaccount.blob.core.windows.net/mycontainer/myblob.
  • Storage access key: This is the 512 bit access key generated by Windows Azure when you create a storage account. there will be two keys, primary and secondary. You can choose to regenerate the keys at a later point if required

Blobs:   Blobs are mainly used to store large amount of  unstructured data . All blobs must be created inside a container, there can be unlimited number of these in an account. There can be two types of blobs- Page blobs(maximum size of 1TB) and block blobs(maximum size of 200GB)

Tables: Tables are used to store structured but non-relational data. It is a NoSQL datastore that can service authenticated calls from inside and outside of Windows Azure cloud.Table is a collection of entities, but it doesnt force a schema on the entities.This means that the a single table can have entities with different set of properties. Entity is a set of property, similar to a DB row. It can be upto 1 MB in size. Whereas Property is a name-value pair. An entity can have upto 252 properties for storing data. Each Entity will have three system defined properties ie apartition key,row key and a timestamp

Queues:  It is a service for storing messages, that can be accessed using authenticated http or https calls. A single queue message can be upto 64 KB in size. It can have millions of messages , limited only by the maximum storage capacity. It is mostly useful in scenarios where there is a backlog of messages to be processes asynchronously or to pass messages from the Windows Azure web role to a worker role.

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