Let’s start from basics.
What is Blob –?
BLOB stands for Binary Large Object. In simple words a BLOB is collection of binary data as a single entity.
Windows Azure Blob is one of the parts of Windows Azure Storage Service. Windows Azure Blob is the simplest way to store text or binary data with windows azure.
The Azure Blob Storage offers two types of blobs –
1. Block Blob
2. Page Blob
Block Blob –
Block blob is made of block each having unique blockID. Block blobs are used when you want to manage large files over network. With block blob, you can upload multiple blocks in parallel hence reducing upload time. Maximum block size is 4MB.
Page Blob –
Page blob is collection of pages of size 512 bytes. Page blob is useful when user wants to perform random read and write operations.
When to use Page Blob and Block Blob –
Let’s consider following scenario – You are creating an application for providing online storage of media files. The media files consist of VHD and video files. For VHD’s random read and write operation need to be supported for better performance and video files must be accessed in the sequence of creation. Which two storage types you will use?
It is pretty clear that, as we are storing large files, we need to use blob storage. If we look at specific requirement of VHD’s, it requires random read and write operations to be supported. Hence PAGE BLOB is suitable for storing VHD files. Whereas video files need to be accessed in a sequence therefore BLOCK BLOB is suitable for video files as sequencing can be easily achieved using blockID of block bob.
Hope above example clears the difference.