Microsoft recently announced the general availability of the Azure Blob Storage Cold Tier, an online tier designed explicitly for efficiently storing infrequently accessed or modified data while ensuring immediate availability.
Organizations can use Azure Blob Storage as a platform-as-a-service (PaaS) solution to store massive amounts of unstructured data. The service already had three tiers, hot, cool, and archive, introduced end of 2017 – and the company has now added a cold tier to expand the further options for users to choose the correct tier based on the frequency of accessing- and retaining data. The read latency is milliseconds on the cold tier.
With the new blob storage tier, the company claims it is the "most cost-effective Azure Blob Storage offering to store infrequently accessed data with long-term retention requirements while maintaining instant access." The cold tier can be leveraged like hot and cool through REST APIs, SDKs, Azure Portal, Azure PowerShell, and Azure CLI. In addition, the latest version of the Azure Storage Explorer tool maintained by Microsoft is extended to support the cold tier allowing users to write, manage, and read their data directly from the cold tier.
Furthermore, the cold tier extends its support to both Blob Storage and Azure Data Lake Storage Gen2. In addition, Locally redundant storage (LRS), Geo-redundant storage (GRS), Read-access Geo-redundant storage (RA-GRS), Zone-redundant storage (ZRS), Geo-zone-redundant storage (GZRS), and Read-access geo-zone-redundant storage (RA-GZRS) are all supported based on regional redundancy availability. However, some features are not yet compatible with the cold tier, such as the change feed feature and object replication.
And finally, the Blob Lifecycle Management Policy also supports automating tiering blobs to cold tier based on conditions including modified time, creation time, and last access time. Sean Feldman, a Microsoft MVP, provides an example in one of his blog posts:
{
"rules": [
{
"enabled": true,
"name": "To-Cold",
"type": "Lifecycle",
"definition": {
"actions": {
"baseBlob": {
"tierToCold": {
"daysAfterModificationGreaterThan": 0
}
}
},
"filters": {
"blobTypes": [
"blockBlob"
],
"prefixMatch": [
"masters/"
]
}
}
}
]
}
With a comment:
This will allow much lower storage costs. Remember, there will be higher access and transaction costs when blobs are accessed. The difference is that these blobs will be available immediately and not eventually, as they would be with the Archived tier.
In addition, in a Reddit thread on the introduction of cold storage earlier this year, a respondent also made a comment on costs:
Small advice for people who are thinking about using different storage tiers, make sure you know the pricing model; it can be extremely costly if you make a wrong decision with this ;)
IE a read operation on archive Tier is 3421 times more expensive than on Premium.
Lastly, the cold tier pricing is positioned between cool and archive, with a 90-day early deletion policy. More details on pricing and availability of Azure Blob Storage tiers are available on the Azure Blob Storage pricing page.