Azure VM Sizes: B, D, E and F Series

You decode size names, compare four families, see which sizes web01 can move to, and do a resize and resize back.

1Decode size names with a small script

Paste this whole block:

function Read-VmSize {
    param([Parameter(Mandatory)][string]$Size)
    $families = @{ B = 'Burstable'; D = 'General purpose'; E = 'Memory optimised'; F = 'Compute optimised'; L = 'Storage optimised'; M = 'Very large memory'; N = 'GPU' }
    $letters = [ordered]@{ a = 'AMD CPU'; p = 'Arm CPU'; l = 'low memory'; t = 'tiny memory'; m = 'more memory'; d = 'local temp disk'; i = 'isolated'; b = 'faster remote disks'; s = 'Premium SSD capable' }
    $m = [regex]::Match($Size, '^Standard_([A-Z]+)(\d+)(-\d+)?([a-z]*)(_v(\d+))?$')
    if (-not $m.Success) { throw "Not a size name I can read: $Size" }
    $f = $m.Groups[1].Value
    $feat = $m.Groups[4].Value.ToCharArray() | ForEach-Object { $letters["$_"] } | Where-Object { $_ }
    [pscustomobject]@{
        Size     = $Size
        Family   = '{0} ({1})' -f $f, $families[$f.Substring(0,1)]
        vCPUs    = [int]$m.Groups[2].Value
        Features = $feat -join ', '
        Version  = if ($m.Groups[6].Success) { 'v' + $m.Groups[6].Value } else { 'v1' }
    }
}
'Standard_B2ats_v2','Standard_D2s_v5','Standard_E2s_v5','Standard_F2s_v2','Standard_D2ds_v5','Standard_B2pts_v2' |
    ForEach-Object { Read-VmSize $_ } | Format-Table -AutoSize

You should see this:

Size              Family                vCPUs Features                                  Version
----              ------                ----- --------                                  -------
Standard_B2ats_v2 B (Burstable)             2 AMD CPU, tiny memory, Premium SSD capable v2
Standard_D2s_v5   D (General purpose)       2 Premium SSD capable                       v5
Standard_E2s_v5   E (Memory optimised)      2 Premium SSD capable                       v5
Standard_F2s_v2   F (Compute optimised)     2 Premium SSD capable                       v2
Standard_D2ds_v5  D (General purpose)       2 local temp disk, Premium SSD capable      v5
Standard_B2pts_v2 B (Burstable)             2 Arm CPU, tiny memory, Premium SSD capable v2

This output is exact: the script just reads the letters. Notice Standard_B2pts_v2, the free account’s other free size: it’s Arm, which matters in “Break It”.

2Compare real specs from Azure

Run this:

$want = 'Standard_B2ats_v2','Standard_D2s_v5','Standard_E2s_v5','Standard_F2s_v2'
$skus = az vm list-skus --location centralindia --resource-type virtualMachines -o json | ConvertFrom-Json | Where-Object { $want -contains $_.name }
$skus | ForEach-Object {
    $cap = @{}; $_.capabilities | ForEach-Object { $cap[$_.name] = $_.value }
    [pscustomobject]@{ Size = $_.name; vCPUs = $cap.vCPUs; MemoryGB = $cap.MemoryGB; MaxDataDisks = $cap.MaxDataDiskCount; Arch = $cap.CpuArchitectureType }
} | Sort-Object { [double]$_.MemoryGB } | Format-Table -AutoSize

You should see something like this:

Size              vCPUs MemoryGB MaxDataDisks Arch
----              ----- -------- ------------ ----
Standard_B2ats_v2 2     1        4            x64
Standard_F2s_v2   2     4        4            x64
Standard_D2s_v5   2     8        4            x64
Standard_E2s_v5   2     16       4            x64

Same 2 vCPUs, memory from 1 to 16 GiB. Put that next to the prices from Lesson 1 (about USD 4.49, 62, 74 and 95 a month for Linux) and you can explain to anyone why the family matters. az vm list-skus downloads a large list, so it takes a few seconds.

3See what web01 can resize to

Run this:

$opts = az vm list-vm-resize-options --resource-group rg-saat-vms --name web01 --query "[].name" -o tsv
"$($opts.Count) sizes available"
$opts | Where-Object { $_ -match '^Standard_B2' }

You should see something like this:

412 sizes available
Standard_B2als_v2
Standard_B2as_v2
Standard_B2ats_v2
Standard_B2ls_v2
Standard_B2s_v2
...

Because web01 is deallocated, Azure lists every size in the region, not just the ones on its current hardware. A running VM gets a shorter list.

4Resize while deallocated, then put it back

Run this:

az vm resize --resource-group rg-saat-vms --name web01 --size Standard_B2als_v2 -o none
az vm show --resource-group rg-saat-vms --name web01 --show-details --query "{size:hardwareProfile.vmSize, power:powerState}" -o table
az vm resize --resource-group rg-saat-vms --name web01 --size Standard_B2ats_v2 -o none
az vm show --resource-group rg-saat-vms --name web01 --query hardwareProfile.vmSize -o tsv

You should see something like this:

Size               Power
-----------------  --------------
Standard_B2als_v2  VM deallocated
Standard_B2ats_v2

B2als_v2 has 4 GiB of memory (the “l” means low memory compared with B2as_v2’s 8 GiB). Resizing a deallocated VM is instant and costs nothing; you’d only pay once you start it. You put web01 back on the size the free account covers.

5Find the B-series credit metrics

Run this:

$id = az vm show --resource-group rg-saat-vms --name web01 --query id -o tsv
az monitor metrics list-definitions --resource $id --query "[?contains(name.value,'Credit')].name.value" -o tsv

You should see this:

CPU Credits Remaining
CPU Credits Consumed

When a B-series VM feels slow, check CPU Credits Remaining first. A flat line at zero with CPU stuck at the baseline percentage means the VM needs a bigger or non-burstable size.

✅ Checkpoint: You can decode a size name, web01 is back on Standard_B2ats_v2 and still deallocated.