then on the next day the VM is created on a new stamp and the VM runs 30 percent
faster because it is on newer processors. Customers can choose whether they want the
v1 or v2 levels of performance. Azure measures CPU performance using Azure
Compute Units (ACU), which are documented at https://azure.microsoft.com/en-
us/documentation/articles/virtual-machines-windows-sizes/#performance-
considerations.
The aforementioned article lists all sizes for all available series. Table 12.1 contains a
subset of the sizes available for the A series to demonstrate some of the combinations
of CPU and memory, in addition to temporary storage and network resource
differences.
Table 12.1: Subset of Microsoft Azure IaaS Virtual Machine Sizes for A Series
Size CPU
CoresMemoryTemporary
Storage
(GB)Maximum
Number of Data
DisksMaximum Number
of Network
Adapters
Extra
Small
(A0)Shared768MB 20 1 1Small
(A1)1 1.75GB 70 2 1
Medium
(A2)2 3.5GB 135 4 1
Large
(A3)4 7GB 285 8 2
Extra
Large
(A4)8 14GB 605 16 4
A5 2 14GB 135 4 1
A6 4 28GB 285 8 2
A7 8 56GB 605 16 4
A8 8 56GB 382 16 2
A9 16 112GB 382 16 4
A10 8 56GB 382 16 2
A11 16 112GB 382 16 4
Source: https://azure.microsoft.com/en-us/documentation/articles/ virtual-machines-windows-sizes/
The sizes also refer to the number of data disks that can be connected, which can be
up to 1TB each and have a 500 IOPs limit (for a standard pricing tier VM. For the A
series, a Basic pricing tier also has a 300 IOPS per disk limit and restricted set of
features, which are designed for test/dev scenarios where the cheapest possible cost is