Set Blob Tier

Article
11/07/2023

The Set Blob Tier operation sets the access tier on a blob. The operation is allowed on a page blob in a premium storage account and on a block blob in a blob storage or general purpose v2 account. A premium page blob's tier (P4/P6/P10/P15/P20/P30/P40/P50/P60) determines the allowed size, IOPS, and bandwidth of the blob. A block blob's tier determines Hot/Cool/Cold/Archive storage type. This operation does not update the blob's ETag.

For detailed information about block blob-level tiering, see Hot, cool, and archive storage tiers.

Request

You can construct the Set Blob Tier request as follows. We recommend that you use HTTPS. Replace myaccount with the name of your storage account, and replace myblob with the blob name for which the tier is to be changed.

Method	Request URI	HTTP version
`PUT`	`https://myaccount.blob.core.windows.net/mycontainer/myblob?comp=tier`	HTTP/1.1

URI parameters

You can specify the following additional parameters on the request URI:

Parameter	Description
`snapshot`	Optional. The snapshot parameter is an opaque `DateTime` value that, when present, specifies the blob snapshot to set a tier on. For more information about working with blob snapshots, see Create a snapshot of a blob
`versionid`	Optional for version 2019-12-12 and later. The `versionid` parameter is an opaque `DateTime` value that, when present, specifies the version of the blob to set a tier on.
`timeout`	Optional. The `timeout` parameter is expressed in seconds. For more information, see Set time-outs for Blob Storage operations.

Request headers

The required and optional request headers are described in the following table:

Request header	Description
`Authorization`	Required. Specifies the authorization scheme, storage account name, and signature. For more information, see Authorize requests to Azure Storage.
`Date` or `x-ms-date`	Required. Specifies the Coordinated Universal Time (UTC) for the request. For more information, see Authorize requests to Azure Storage.
`x-ms-access-tier`	Required. Indicates the tier to be set on the blob. For a list of allowed premium page blob tiers, see High-performance Premium Storage and managed disks for VMs. For blob storage or general purpose v2 account, valid values are `Hot`, `Cool`, `Cold`, and `Archive`. Note: `Cold` tier is supported for version 2021-12-02 and later. For detailed information about standard blob account blob level tiering see Hot, cool and archive storage tiers.
`x-ms-version`	Required for all authorized requests. Specifies the version of the operation to use for this request. For more information, see Versioning for the Azure Storage Services.
`x-ms-client-request-id`	Optional. Provides a client-generated, opaque value with a 1-kB character limit that is recorded in the analytics logs when storage analytics logging is enabled. Using this header is highly recommended for correlating client-side activities with requests received by the server. For more information, see About Storage Analytics Logging.
`x-ms-rehydrate-priority`	Optional. Indicates the priority with which to rehydrate an archived blob. Supported on version 2019-02-02 and newer for block blobs. Valid values are `High`/`Standard`. The priority can be set on a blob only once for versions prior to 2020-06-12; this header will be ignored on subsequent requests. The default priority setting is `Standard`. Beginning with version 2020-06-12, the rehydration priority can be updated after it was previously set. The priority setting can be changed from `Standard` to `High` by calling Set Blob Tier with this header set to `High` and setting `x-ms-access-tier` to the same value as previously set. The priority setting cannot be lowered from `High` to `Standard`.

This operation also supports the use of conditional headers to tier the blob only if a specified condition is met. For more information, see Specify conditional headers for Blob Storage operations.

Request body

None.

Response

The response includes an HTTP status code and a set of response headers.

Status code

A successful operation returns status code 200 (OK) if the new tier takes effect immediately, or status code 202 (Accepted) if the transition to the new tier is pending.

For premium storage accounts, the page blob operation returns status code 200 (OK).

For block blobs, the HTTP status codes that are returned, based on the current and requested tiers of the blob, are described in the following table:

Tier	Set to hot tier	Set to cool tier	Set to cold tier	Set to archive tier
Blob in hot tier	200	200	200	200
Blob in cool tier	200	200	200	200
Blob in cold tier	200	200	200	200
Blob in archive tier	202	202	202	200
Blob in archive tier, rehydrating to hot	202	409	409	409
Blob in archive tier, rehydrating to cool	409	202	409	409
Blob in archive tier, rehydrating to cold	409	409	202	409

For more information about status codes, see Status and error codes.

Response headers

The response for this operation includes the following headers. The response may also include additional standard HTTP headers. All standard headers conform to the HTTP/1.1 protocol specification.

Response header	Description
`x-ms-request-id`	Uniquely identifies the request that was made and can be used to troubleshoot the request. For more information, see Troubleshoot API operations.
`x-ms-version`	The Blob Storage version that was used to execute the request. This header is returned for requests made against version 2009-09-19 and later.
`x-ms-client-request-id`	Can be used to troubleshoot requests and corresponding responses. The value of this header is equal to the value of the `x-ms-client-request-id` header if it's present in the request and the value contains no more than 1,024 visible ASCII characters. If the `x-ms-client-request-id` header isn't present in the request, it won't be present in the response.

Authorization

Authorization is required when calling any data access operation in Azure Storage. You can authorize the Set Blob Tier operation as described below.

Azure Storage supports using Microsoft Entra ID to authorize requests to blob data. With Microsoft Entra ID, you can use Azure role-based access control (Azure RBAC) to grant permissions to a security principal. The security principal may be a user, group, application service principal, or Azure managed identity. The security principal is authenticated by Microsoft Entra ID to return an OAuth 2.0 token. The token can then be used to authorize a request against the Blob service.

To learn more about authorization using Microsoft Entra ID, see Authorize access to blobs using Microsoft Entra ID.

Permissions

Listed below are the RBAC action necessary for a Microsoft Entra user, group, or service principal to call the Set Blob Tier operation, and the least privileged built-in Azure RBAC role that includes this action:

Azure RBAC action: Microsoft.Storage/storageAccounts/blobServices/containers/blobs/write
Least privileged built-in role: Storage Blob Data Contributor

To learn more about assigning roles using Azure RBAC, see Assign an Azure role for access to blob data.

A shared access signature (SAS) provides secure delegated access to resources in a storage account. With a SAS, you have granular control over how a client can access data. You can specify what resource the client may access, what permissions they have to those resources, and how long the SAS is valid.

The Set Blob Tier operation supports three types of shared access signatures: user delegation SAS, service SAS, and account SAS.

As a security best practice, we recommend that you use Microsoft Entra credentials rather than the storage account key, which can be more easily compromised. If your application design requires shared access signatures, use Microsoft Entra credentials to create a user delegation SAS, when possible.

When Shared Key access is disallowed for the storage account, a service SAS token or an account SAS token will not be permitted on a request to Blob Storage. To learn more, see Understand how disallowing Shared Key affects SAS tokens.

User delegation SAS

A user delegation SAS is secured with Microsoft Entra credentials and also by the permissions specified for the SAS.

Calling the Set Blob Tier operation using a SAS token delegated to a container or blob resource requires the Write (w) permission as part of the user delegation SAS token.

To learn more about the user delegation SAS, see Create a user delegation SAS.

Service SAS

A service SAS is secured with the storage account key. A service SAS delegates access to a resource in a single Azure Storage service, such as blob storage.

Calling the Set Blob Tier operation using a SAS token delegated to a container or blob resource requires the Write (w) permission as part of the service SAS token.

To learn more about the service SAS, see Create a service SAS.

Account SAS

An account SAS is secured with the storage account key. An account SAS delegates access to resources in one or more of the storage services. All of the operations available via a service or user delegation SAS are also available via an account SAS.

The following table indicates the signed resource type and signed permissions to specify when delegating access:

Operation	Signed service	Signed resource type	Signed permission
Set Blob Tier	Blob (b)	Object (o)	Write (w)

To learn more about the account SAS, see Create an account SAS.

Remarks

Setting a blob's tier for page blobs in premium accounts has the following restrictions:

The new blob tier can't be lower than the existing one.
The new blob tier should be able to accommodate the blob's content length. For a list of tiers and their allowed content length, see High-performance premium storage and managed disks for VMs.

Setting the block blob's tier on a Blob Storage or general purpose v2 account has the following restrictions:

Setting a tier on a snapshot is allowed as of REST version 2019-12-12.
Snapshots that are tiered to archive can't be rehydrated back into the snapshot. That is, the snapshot can't be brought back to a hot or cool tier. The only way to retrieve the data from an archive snapshot or version is to copy it to a new blob.
If the version is a root blob, it can be rehydrated back to hot or cool.
Snapshots or versions in an archive state aren't allowed to be promoted to root.
When versioning is enabled, the deletion of a root blob when it's in a rehydrate-pending state will result in the cancellation of the rehydration, and the version will be in an archive state.
If a blob is overwritten when it's in a rehydrate-pending and soft-deleted state, it will result in the cancellation of the rehydration, and the version of the soft-deleted snapshot will be in an archive state.

The list of supported tiers is not restricted by the request version, and new tiers may be added in the future.

Note

For detailed information about block blob level tiering see Hot, cool, and archive storage tiers.

Billing

Pricing requests can originate from clients that use Blob Storage APIs, either directly through the Blob Storage REST API, or from an Azure Storage client library. These requests accrue charges per transaction. The type of transaction affects how the account is charged. For example, read transactions accrue to a different billing category than write transactions. The following table shows the billing category for Set Blob Tier requests based on the storage account type:

Operation	Storage account type	Billing category
Set Blob Tier (tier down)	Premium block blob Standard general-purpose v2	Write operations
Set Blob Tier (tier up)	Premium block blob Standard general-purpose v2	Read operations

To learn about pricing for the specified billing category, see Azure Blob Storage Pricing.