Move Azure storage blobs using AzCopy


The AzCopy command is a command-line utility specially created and optimized for moving data in and out of Azure storage. Running AzCopy, you can bulk-transfer from the local file system of an on-premises computer to the cloud.

In this unit, you'll learn how to run the AzCopy utility to upload, download, and transfer blob data between storage accounts.

What is AzCopy?

The AzCopy utility is designed and optimized for performing large-scale bulk transfers of data to and from Azure storage. Run AzCopy to transfer entire directory structures from your local computer into blob storage and back again.

AzCopy performs its operations asynchronously, and can use multiple concurrent threads to read and write data. Additionally, it's fault-tolerant. If a transfer is interrupted for some reason and fails, AzCopy can resume the operation from where it left off after the situation is resolved.

The latest version of AzCopy lets you take incremental backups of blobs, and can keep the contents of blob storage accounts synchronized so that they contain the same version of data.

Upload data

From the command line, you can call AzCopy using the all lower-case name azcopy, with additional parameters depending on the operation you want to perform. Run the azcopy copy command to upload data to Azure storage. The simplest form of this command copies a file to a blob. The following example uploads the contents of a file named myfile.txt to a blob, also named myfile.txt, to the mycontainer container in the myaccount blob storage account. The storage account and container must already exist.

azcopy copy "myfile.txt" ""

The AzCopy command requires that you're authenticated and authorized to access the storage account. If your organization uses Active Directory Federation Service (ADFS), you can authenticate by running the azcopy login command and signing in. Alternatively, the owner of a storage account can create a Shared Access Signature (SAS) token that provides access to the storage account. The SAS token is time-limited, and can be restricted to only allow certain operations. You provide the SAS token as a query string to the Azure storage URL when you upload or download data.

azcopy copy "myfile.txt" "<sas token>"

You can upload multiple files and complete folder structures with AzCopy. The --recursive=true option walks the folder structure starting at the specified point, and creates a corresponding structure of blobs in your container in Azure storage. You can also specify that only files whose names match a particular pattern are uploaded by using wildcard pattern matching. The following example uploads all files under the myfolder folder and subfolders.

azcopy copy "myfolder" "<sas token>" --recursive=true

Monitor and manage jobs

Remember that AzCopy runs asynchronously. If you're transferring a large number of files, or even a small number of large files, AzCopy starts your upload and reports an initial summary. The command then continues running in the background. Run the AzCopy jobs list command to view the status of running and recently completed commands. Each job has an ID, and you can view the details of a job with the AzCopy jobs show <id> command.

If an AzCopy transfer is interrupted, it appears in the jobs list. Restart the job by running the azcopy jobs resume <id> command.

Download data

Run the AzCopy copy command to download data from blob storage. The following example transfers the data in the blob myblob to a local folder named myblobdata.

azcopy copy "<sas token>" "myblobdata"

As with uploads, you can use wildcards to download multiple blobs with matching names, and iterate through the blob container hierarchy with the --recursive=true flag.

Copy data between storage accounts and synchronize storage

The final use of the AzCopy copy command is to transfer blobs between storage accounts. The following example copies the blobs from sourcecontainer in the sourceaccount storage account to destcontainer in destaccount. This example requires two SAS tokens: one for the source account and another for the destination account.

azcopy copy "*?<source sas token>" "*?<dest sas token>"

The --recursive=true flag is available if your container has a hierarchical set of blobs.

When the source and destination of the AzCopy command are both Azure storage accounts, the command performs the transfer using the Azure storage service. It doesn't download and upload blobs via your computer.

Another way to copy blobs between storage accounts is to run the AzCopy sync command. This command synchronizes the contents of a destination container with a source container, by either copying blobs if they aren't found in the destination or if the last modified time of a blob in the destination is earlier than that of the corresponding blob in the source. This command also provides the --delete-destination flag. If you set this flag to true, AzCopy will delete blobs in the destination that don't exist in the source. Use this option with caution.

Manage blobs

You can view the blobs available in a container with the AzCopy list command. The following example displays the blobs in the sourcecontainer container.

azcopy list "<sas token>"

You can create a new container in a blob storage account by running the AzCopy make command, like this.

azcopy make "<sas token>"

To remove a blob, run the AzCopy remove command. You can remove all blobs with names that match a specific pattern with the --include flag, and you can walk through a hierarchical container with the --recursive flag. The following example removes all blobs with the txt suffix from mycontainer.

azcopy remove "<sas token>" --include "*.txt" --recursive=true

Configure concurrency

You can control the performance and resource utilization of the AzCopy command by setting the AZCOPY_CONCURRENCY_VALUE environment variable. AzCopy uses the value of this variable to specify the number of concurrent threads it will use for transferring data. By default, it's set to 300. You can reduce this value if you need to control the bandwidth and CPU utilization of your copy operations.