There are two kinds of Blobs as part of Microsoft's Azure Blob Storage model.
Block Blobs:
Block blobs are comprised of blocks, each of which is identified by a block ID. Each block can be different in size, up to a maximum of 4 MB per block. The maximum size for a block blob is 200 GB, and a block blob can include up to 50,000 blocks. When a block blob upload is larger then the size of a single block, the file gets broken across multiple blocks.
Block blobs allow you to upload multiple blocks in parallel to decrease upload time. Each block includes a hash to verify the transfer, so you can track upload progress and re-send blocks as needed. You can upload blocks in any order, and determine their sequence in the final block list commitment step. You can also upload a new block to replace an existing uncommitted block of the same block ID.
Page Blobs:
Page blobs are a collection of pages for read and write operations. Each page is 512 bytes in size and the maximum size for a page blob is 1 TB.
Page blobs allow you to concurrently write to overlapping pages sequentially to keep pace on read/write operations. Unlike blocks, pages have an inherent order and need to be uploaded/written/read to in a sequential order. Pages can also be replaced and overwritten.
Block Blobs:
Block blobs are comprised of blocks, each of which is identified by a block ID. Each block can be different in size, up to a maximum of 4 MB per block. The maximum size for a block blob is 200 GB, and a block blob can include up to 50,000 blocks. When a block blob upload is larger then the size of a single block, the file gets broken across multiple blocks.
Block blobs allow you to upload multiple blocks in parallel to decrease upload time. Each block includes a hash to verify the transfer, so you can track upload progress and re-send blocks as needed. You can upload blocks in any order, and determine their sequence in the final block list commitment step. You can also upload a new block to replace an existing uncommitted block of the same block ID.
Page Blobs:
Page blobs are a collection of pages for read and write operations. Each page is 512 bytes in size and the maximum size for a page blob is 1 TB.
Page blobs allow you to concurrently write to overlapping pages sequentially to keep pace on read/write operations. Unlike blocks, pages have an inherent order and need to be uploaded/written/read to in a sequential order. Pages can also be replaced and overwritten.
Types of Blobs
Architecture
Microsoft's Azure Blob Storage is one of the storage services offered as part of Azure Storage. The other services being Queues and Tables. Blob stands for “binary large object”. They are similar to files that you would store on a regular computer. Blob files can include csv documents, VHDs, pictures, movies...etc. The blobs are stored in Microsoft’s cloud servers, and can be accessed through REST APIs, URLs, or using a Storage Client Library.
Storage Account: A storage account is a registration to provide access to Azure Storage Services
Container: A container provides a grouping of a set of blobs. All blobs must be in a container. An account can contain an unlimited number of containers. A container can store an unlimited number of blobs.
Blob: A Blob is a collection of pages or blocks that comprise a chunk of memory. The maximum size for a Block Blob is 200GB and can include up to 50,000 blocks. The maximum size for a Page Blob is 1TB for a Page Blob and can include up to 2,000,000,000 pages.
Pages/Blocks: A Page or Block is the smallest unit of storage. Blocks are used for Block Blob Storage while Page Blob Storage uses Pages. Each block can be a different size, up to a maximum of 4 MB. Each page is a 512 byte page .
Container: A container provides a grouping of a set of blobs. All blobs must be in a container. An account can contain an unlimited number of containers. A container can store an unlimited number of blobs.
Blob: A Blob is a collection of pages or blocks that comprise a chunk of memory. The maximum size for a Block Blob is 200GB and can include up to 50,000 blocks. The maximum size for a Page Blob is 1TB for a Page Blob and can include up to 2,000,000,000 pages.
Pages/Blocks: A Page or Block is the smallest unit of storage. Blocks are used for Block Blob Storage while Page Blob Storage uses Pages. Each block can be a different size, up to a maximum of 4 MB. Each page is a 512 byte page .
Topology
Listed below is an example of the topology of Blob Storage used for a Virtual Machine on Microsoft Azure.
In this example, each of the drives of the virtual machine is mapped to a virtual hard drive file (VHD). Each VHD is a Block Blob. All of the Block Blobs are stored together in a container and that container is linked to an Azure Storage Account. If this virtual machine ever needed to be migrated, all of the respective drives/blobs would need to be moved and a new virtual machine needs to be setup to point to them. This decentralization of storage allows for quick and easy migration of servers on Azure.
In this example, each of the drives of the virtual machine is mapped to a virtual hard drive file (VHD). Each VHD is a Block Blob. All of the Block Blobs are stored together in a container and that container is linked to an Azure Storage Account. If this virtual machine ever needed to be migrated, all of the respective drives/blobs would need to be moved and a new virtual machine needs to be setup to point to them. This decentralization of storage allows for quick and easy migration of servers on Azure.