For a MOVEit Transfer deployment that leverages Azure Blob storage, an Azure Blob is conceptually equivalent to a MOVEit Transfer file. However, from the perspective of Azure Storage, it is useful to know that very large files can require adjustments to Blob block size. An Azure Block Blob can have a maximum of 50,000 blocks, but block size is configurable up to 100MB.

Therefore, consider these guidelines to increase the allowed file size when you deploy your MOVEit Transfer file store to Azure Blobs.

  • The default Blob size for an Azure Block Blob is smaller than a default maximum file size allowed on a Windows Server (NTFS) File System.
  • Max Blob size can be adjusted to accommodate a MOVEit Transfer deployment that has very large Blobs (where actual files are > 1TB and < 4.7 TB).

Adjusting Maximum File Size (MaxBlockBytes)

When configured to leverage Azure Storage, MOVEit Transfer currently leverages Block Blobs. Blob block size is controlled by the FSAzureBlockBlob registry key set by the MOVEit Transfer installer or the Blob Conversion Assistant.

Background

The following points are helpful when considering the best block size for your instance of MOVEit Transfer:

  • In Azure Blob Storage, MOVEit Transfer files are stored as Blobs.
  • Each Blob can span a maximum of 50,000 blocks.
  • The default block size currently equals about 25MB (26214400 Bytes). (Factored by 50,000 blocks yields a default max Blob size of 1.2 TB)
  • You can adjust the maximum file size that a Blob will accommodate by adjusting the maximum size of its blocks.
  • While larger blocks can maximize the supported file size, which can be calculated as max block count (50,000 blocks) factored by max block size, it also means that MOVEit Transfer Server can require more memory (RAM) to handle uncommitted blocks.
    Tip: Blobs can be comprised as block, page, or append Blobs, but MOVEit Transfer leverages block Blobs.

Adjust the Maximum File Size at the MOVEit Transfer Server

To Adjust Maximum File Size Within Your Azure Blob Storage File Store.

  1. Go to the Windows Server machine running the MOVEit Transfer Server (for web farm deployment patterns, this would be the primary MOVEit Transfer node) and find the following registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Standard Networks\siLock\FSAzureBlockBlob

  2. FSAzureBlockBlob can have an optional REG_DWORD subkey for block size (MaxBlockBytes). If it is not there, you can add it.
    Note: MaxBlockBytes must be a value between 1048576 (1MB) and 104857600 (100MB), inclusive. An Azure Storage Service block size of 100MB can yield a max Blob of around 4.75TB. Values outside this range can cause exceptions when you start/restart MOVEit Transfer services.