Storage accounts, redundancy and tiers
Storage accounts
A storage account is the container for your Azure Storage data objects: blobs, files, queues and tables. It gives your data a unique namespace that is reachable from anywhere over HTTP or HTTPS:
https://<account-name>.blob.core.windows.netThe account name must be globally unique across all of Azure, 3 to 24 characters, and use lowercase letters and numbers only. Each service in the account gets its own endpoint:
| Service | Endpoint |
|---|---|
 Blob Storage | https://<account>.blob.core.windows.net |
 Data Lake Storage | https://<account>.dfs.core.windows.net |
 Azure Files | https://<account>.file.core.windows.net |
 Queue Storage | https://<account>.queue.core.windows.net |
 Table Storage | https://<account>.table.core.windows.net |
Storage account types
| Type | Supports | Redundancy | Use it for |
|---|---|---|---|
| Standard general-purpose v2 | Blob (including Data Lake Storage), Queue, Table, Azure Files | LRS, GRS, RA-GRS, ZRS, GZRS, RA-GZRS | most scenarios: the default choice |
| Premium block blobs | block blobs and append blobs | LRS, ZRS | high transaction rates, small objects, consistently low latency |
| Premium file shares | Azure Files | LRS, ZRS | enterprise or high-performance file shares |
| Premium page blobs | page blobs only | LRS | the random-access storage behind VM disks |
Standard accounts run on hard drives (HDD) and cost less per gigabyte; premium accounts run on solid-state drives (SSD) for speed.
Redundancy: how many copies, and where
Azure Storage always keeps multiple copies of your data. You choose how far apart they are:
| Option | Copies | Where | Protects against |
|---|---|---|---|
| LRS, locally redundant | 3 | one data centre in the primary region | a single server or drive failing |
| ZRS, zone-redundant | 3 | three availability zones in the primary region | a whole data centre (zone) going down |
| GRS, geo-redundant | 6 | LRS in the primary region plus LRS in the paired secondary region | a whole region going down |
| GZRS, geo-zone-redundant | 6 | ZRS in the primary region plus LRS in the secondary region | zone failure and region failure |
LRS is the cheapest and least durable; GZRS the most durable.
With GRS and GZRS, the secondary copy is only readable after a failover. RA-GRS and RA-GZRS (read-access) let you read from the secondary region at any time.
Access tiers for blobs
Not all data is used equally, so blob storage has tiers. The less often you read data, the cheaper it is to store and the more it costs to access:
| Tier | For data that is | Notes |
|---|---|---|
| Hot | accessed frequently | highest storage cost, lowest access cost |
| Cool | accessed infrequently, kept at least 30 days | cheaper storage |
| Cold | rarely accessed, kept at least 90 days | cheaper still |
| Archive | rarely accessed, kept at least 180 days, can wait hours for retrieval | cheapest storage; offline, must be rehydrated before reading, which can take hours |
Hot, cool and cold can be set as the account's default tier; archive can only be set on individual blobs. Moving a blob out of cool, cold or archive before its minimum period ends incurs an early deletion charge for the remaining days. A newer smart tier option can move blobs between hot, cool and cold automatically, based on how they are used.