VM Quota Validation Guide
Check Azure VM/VMSS quota availability before recommending or deploying. Ensures the subscription and region have sufficient vCPU capacity.
⚠️ NEVER use the
azure-quotaMCP server as as It is unreliable. Always tryaz quotaCLI commands first.
Quota Structure
VM quotas are tracked at two levels under Microsoft.Compute:
| Quota Level | Resource Name | What It Limits |
|---|---|---|
| Total Regional | cores |
All vCPUs across all families in a region |
| Per-Family | e.g., standardDSv3Family |
vCPUs for a specific VM family |
⚠️ Both levels must have capacity. A deployment fails if either is exceeded.
Common Quota Resource Names
See vm-families.md for quota resource names per VM family. Use az quota list to discover names not listed there.
⚠️ Do NOT guess quota names from SKU names. Use
az quota listto discover correct resource names.
Quota Check Workflow
Option A: az vm list-usage (Recommended for VM quotas)
No extension required. Returns both current usage and limit in a single call for all VM families in a region — equivalent to running az quota usage show and az quota list together for VM vCPU quotas.
# All VM family quotas in a region
az vm list-usage --location <region> -o table
# Filter to a specific family
az vm list-usage --location <region> --query "[?contains(name.value,'<quotaName>')].{Name:name.localizedValue, QuotaName:name.value, Current:currentValue, Limit:limit}" -o table💡 Tip:
az vm list-usageis the simplest way to check VM quotas. Useaz quota(Option B) when you need to request quota increases or manage quotas for non-VM resource types.
Option B: az quota CLI (For quota increases or non-VM resources)
Prerequisite: az extension add --name quota
| Step | Command | Purpose |
|---|---|---|
| 1. Discover names | az quota list --scope /subscriptions/<sub-id>/providers/Microsoft.Compute/locations/<region> -o table |
Find quota resource name for the VM family |
| 2. Check usage | az quota usage show --resource-name <name> --scope ... |
Current vCPU consumption |
| 3. Check limit | az quota show --resource-name <name> --scope ... |
Maximum allowed vCPUs |
| 4. Check regional | Repeat steps 2–3 with --resource-name cores |
Total regional vCPU cap |
Calculate Capacity
Available = Limit - Current Usage (check both family AND regional)
vCPUs Needed = vCPUs per VM × Instance Count
✅ Deploy if: vCPUs Needed ≤ min(Family Available, Regional Available)
❌ Blocked if: either is exceededExample: 3× Standard_D4s_v5 (4 vCPUs each) = 12 needed. Family: 100−40 = 60 ✅. Regional: 350−280 = 70 ✅.
Handling Insufficient Quota
| Option | Action |
|---|---|
| Request increase | az quota update --resource-name <name> --scope ... --limit-object value=<new-limit> --resource-type dedicated. Most increases auto-approve within minutes. |
| Try different region | Run the quota check workflow against alternative regions to find available capacity |
| Switch VM family | Recommend an alternative family with quota (e.g., D-series full → Dads v5 AMD variant) |
VMSS Considerations
For scale sets, validate against autoscale maximum: vCPUs per VM × Max Instance Count.
| Autoscale Setting | vCPUs to Validate |
|---|---|
| Fixed count (5 instances) | vCPUs × 5 |
| Autoscale min=2, max=10 | vCPUs × 10 |
Error Reference
| Error | Cause | Action |
|---|---|---|
QuotaExceeded |
Family vCPU limit reached | Request increase or change family/region |
OperationNotAllowed |
Subscription lacks capacity | Request quota increase |
cores limit hit |
Regional vCPUs exhausted | Request regional increase |
| CLI commands fail entirely | Auth/extension issue | Use MCP fallback (see below) |
Related Resources
- Invoke the azure-quotas skill for complete quota CLI workflows across all Azure providers
- VM Family Guide — Family-to-workload mapping
- Azure VM quotas documentation