Azure Storage Cost Optimization

Reference guide for identifying cost savings opportunities in Azure Storage accounts through tier analysis, lifecycle policies, and orphaned resource detection.

Subscription Input Options

Accept any of these identifiers to identify subscriptions for analysis:

Cost Optimization Rules

When analyzing each storage account, apply these prioritized rules:

Access Tier Decision Matrix

Note: Archive tier has retrieval costs and rehydration delays (hours). Only use for data that rarely needs access.

Lifecycle Policy Template

Recommend this baseline policy for accounts without lifecycle management:

{
  "rules": [
    {
      "name": "move-to-cool-after-30-days",
      "type": "Lifecycle",
      "definition": {
        "actions": {
          "baseBlob": {
            "tierToCool": { "daysAfterLastAccessTimeGreaterThan": 30 }
          }
        },
        "filters": { "blobTypes": ["blockBlob"], "prefixMatch": [] }
      }
    },
    {
      "name": "move-to-archive-after-180-days",
      "type": "Lifecycle",
      "definition": {
        "actions": {
          "baseBlob": {
            "tierToArchive": { "daysAfterLastAccessTimeGreaterThan": 180 }
          }
        },
        "filters": { "blobTypes": ["blockBlob"], "prefixMatch": [] }
      }
    },
    {
      "name": "delete-old-snapshots",
      "type": "Lifecycle",
      "definition": {
        "actions": {
          "snapshot": {
            "delete": { "daysAfterCreationGreaterThan": 90 }
          }
        },
        "filters": { "blobTypes": ["blockBlob"] }
      }
    },
    {
      "name": "delete-old-versions",
      "type": "Lifecycle",
      "definition": {
        "actions": {
          "version": {
            "delete": { "daysAfterCreationGreaterThan": 90 }
          }
        },
        "filters": { "blobTypes": ["blockBlob"] }
      }
    }
  ]
}

⚠️ Important: Lifecycle policies that use daysAfterLastAccessTimeGreaterThan require last access time tracking to be enabled on the storage account. Verify with: az storage account blob-service-properties show --account-name <name> --resource-group <rg> --query lastAccessTimeTrackingPolicy

Resource Graph Queries

Find storage accounts without lifecycle policies:

Use Azure CLI to check lifecycle policy presence (not queryable via Resource Graph):

az storage account management-policy show --account-name <name> --resource-group <rg>

Find Premium storage accounts in non-production:

Resources
| where type =~ 'microsoft.storage/storageaccounts'
| where sku.name contains 'Premium'
| where tags.environment in~ ('dev', 'test', 'staging', 'sandbox')
| project name, resourceGroup, sku=sku.name, tags

Find GRS/GZRS accounts in dev/test (redundancy downgrade candidates):

Resources
| where type =~ 'microsoft.storage/storageaccounts'
| where sku.name contains 'GRS' or sku.name contains 'GZRS'
| where tags.environment in~ ('dev', 'test', 'staging')
| project name, resourceGroup, sku=sku.name, location, tags

Find classic (v1) storage accounts:

Resources
| where type =~ 'microsoft.storage/storageaccounts'
| where kind =~ 'Storage'
| project name, resourceGroup, location, kind

Find orphaned managed disks (unattached):

Resources
| where type =~ 'microsoft.compute/disks'
| where isempty(managedBy)
| project name, resourceGroup, location, diskSizeGb=properties.diskSizeGB, sku=sku.name

Report Templates

Subscription-Level Summary

Include: subscription name/ID, total monthly storage cost, account count by SKU/tier, total data stored (TB), top issues found.

Detailed Storage Account Analysis

Include: account name, resource group, SKU/redundancy, kind, monthly cost, capacity (GB), access tier distribution (%), lifecycle policy status, and optimization recommendations.

Tools & Commands

MCP Tool: azure__storage with sub-commands for account and container operations

Azure CLI:

• az storage account list --subscription <id> - List accounts
• az storage account show --name <name> --resource-group <rg> - Get details
• az storage account management-policy show --account-name <name> --resource-group <rg> - Check lifecycle policy
• az storage account blob-service-properties show --account-name <name> --resource-group <rg> --query lastAccessTimeTrackingPolicy - Check access tracking
• az monitor metrics list --resource <id> --metric UsedCapacity - Capacity metrics
• az monitor metrics list --resource <id> --metric Transactions --dimension ApiName - Access patterns

Pricing Quick Reference

Tiers ranked by storage cost (East US, LRS, approximate):

• Hot: $0.018/GB/mo (cheapest reads)
• Cool: $0.01/GB/mo (30-day minimum retention)
• Cold: $0.0036/GB/mo (90-day minimum)
• Archive: $0.002/GB/mo (180-day minimum, hours to rehydrate)

Always validate from official pricing.

Redundancy savings: Downgrading from GRS to LRS saves ~50%. Dev/test rarely needs GRS/GZRS.