[AZURE 70-534 - Cheat Sheet and Exam Notes Part-7] Architect an Azure Compute infrastructure

Series Index 

1. Azure ARM , networking and GLOBAL Infrastructure (2017-10-01)
2. Securing Resources and Azure Security (2017-10-01)
3. Design an application storage and data access strategy (2017-10-01) 
4. Design advanced applications (2017-10-01)
5. Design Azure Web and Mobile Apps (2017-10-01)
6. Design a management, monitoring, and business continuity strategy (2017-10-01)
7. Architect an Azure Compute infrastructure (2017-10-01)

Azure Global Compute Infrastructure 

1. Virtual machine Series
1. There are two families are VM Current Generation and Previous Generation 

2. VM Family	Previous Generation	Current Generation
   General Purpose	D1-4 – v1 A0-7 – Standard	B-series (in preview) A0-4 Basic Av2 Standard D2-64 v3 latest generation D2s-64s v3 latest generation D2-5 v2 limited-time special pricing D1-5 v2 DS1-S5 v2
   Memory Optimized	D11-14 – v1	E2-64 v3 latest generation D11-14 v2 limited-time special pricing D11-15 v2 DS11-S15 v2 G-series M-series
   Compute Optimized	None	F-series
   High Performance Compute	A8-11	H-series
   Storage Optimized	None	L-series
   GPU Optimized	None	NC-series NCv2 series NV-series ND-series

3. A Series -  Entry Level General Purpose , DEV, test , compute
1. 300-500 IOPS /data drive max 16 data drive 
2. Options are A0-A11 
3. A0-A4 are very generic and A7-11 are HCP
4. D Series - General Purpose Compute , SSD based , Production class
1. IOPS 500/disk,  2-32 data disk supported 
5. DS Series - Very High IOPS workload 
1. 3200 - 50k IOPS
6. DV2 Series - Next Generation Compute 
7. F Series -Compute Optimized 
8. G Series -  Memory and Storage Optimize 
9. H Series - Next Generation High Performance Computing 
10. L Series - Storage Optimize mainly used for application like large databases 
11. N Series GPU Enabled Graphics Optimized  
2. Premium data disk for VMs
1. Azure Premium Storage delivers high-performance, low-latency disk support for virtual machines (VMs) with input/output (I/O)-intensive workloads. VM disks that use Premium Storage store data on solid-state drives (SSDs). To take advantage of the speed and performance of premium storage disks, you can migrate existing VM disks to Premium Storage.
2. Premium Storage supports DS-series, DSv2-series, GS-series, Ls-series, and Fs-series VMs.
3.  With Premium Storage, Azure offers the ability to truly lift-and-shift demanding enterprise applications like Dynamics AX, Dynamics CRM, Exchange Server, SAP Business Suite, and SharePoint farms to the cloud. 
3. High Performance Compute
1. A8-A11 and H series are called HPC machine 
4. VM Images 
1. Images can be stores either in VM galary or Open Source VM Depot 
2. Custom image capturing required sysprep to run on it 
5. VM Agents 
1. Installed by default on VM is responsible execution of management task
6. VM extension 
1.  First party or Thrid party plug-ins for VMs 
7. The Custom Script Extension 
1. The Custom Script Extension downloads and executes scripts on Azure virtual machines.
2. This extension is useful for post deployment configuration, software installation, or any other configuration / management task. 
8. Desired State Configuration (DSC)
1. Azure Automation DSC is an Azure service that allows you to write, manage, and compile PowerShell Desired State Configuration (DSC) configurations, import DSC Resources, and assign configurations to target nodes, all in the cloud.
2. Azure Automation DSC provides several advantages over using DSC outside of Azure.
9. Auto Scaling 
1. The standard service plan or higher is required for auto-scaling.
10. Availability Sets 
1. The availability set can only be configured when creating a virtual machine. You must recreate the virtual machine to move it in or out of an availability set.
11. Scale Set Vs Placement Group
1. The core difference is that scale sets are Identical vms where availibity does not require them to be identical. 
2. A placement group is a construct similar to an Azure availability set, with its own fault domains and upgrade domains. By default, a scale set consists of a single placement group with a maximum size of 100 VMs. If a scale set property called singlePlacementGroup is set to false, the scale set can be composed of multiple placement groups and has a range of 0-1,000 VMs.
3. Availability set,>>Scale Set>>placement group
12. Azure's Azure Compute Unit (ACU) 
1. Azure have created the concept of the Azure Compute Unit (ACU) to provide a way of comparing compute (CPU) performance across Azure SKUs
2. A1-A7 100 ACU , A8-A11- 225 ACU, H 290-300 ACU , G 180-250 ACU , F 210- 250 ACU
13. Important Point to remembers 
1. Every Azure VM has temporary storage drive (D:) – lost when VM is moved/restarted.
2. VMs may be attached to data disks that persist across VM restarts/redeployments and are locally replicated in-region (and beyond if specified).
3. Can use gallery images or create custom images (to meet custom requirements, e.g. with certain software pre-installed).
4. OS disk always has caching, default Read/Write (data disk caching is optional, default none) – changes need a reboot.
5. Can create a bootable image from an OS disk (not data disk).
6. Can change caching on data disk without reboot.
7. OS disk max 127GB, data disk max 1TB.
8. Only charged for storage used (regardless of what is provisioned).
9. Can take VHDs from on-premises: (Windows Server 2008 R2 SP1 or later), sysprep then upload with Add-AzureVhd -Destination storageaccount/container/name.vhd -LocalFilePath localfile.vhd; for Linux install WALinuxAgent (different preparation for different distributions).
10. Tell cloud service to load balance an endpoint to split load between VMs. With ARM there is the option to define a separate Load Balancer.
11. Encryption at rest for data disks requires third party applications (encryption is in preview though…).
12. Availability set: 2 or more VMs distributed across fault domains and upgrade domains for SLA of 99.95% (no SLA for single VMs).
13. Auto-scaling based on thresholds (mix/max number of instances, CPU utilisation, queue length – between web and worker roles) or time schedule (also time to wait before adding/removing more instances – AKA cooldown period). Needs at least 2 VMs in an availability set.
14. Basic Pricing Tier VMs have no load balancing or auto-scaling.
15. Standard Pricing Tier has similar configuration as of basic but support auto scaling and load balancing. https://azure.microsoft.com/en-us/blog/basic-tier-virtual-machines-2/