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Tech Tips, Tricks & Trivia

by 'Anil' Radhakrishna
A seasoned developer's little discoveries and annotated bookmarks.

Search from over a hundred HOW TO articles, Tips and Tricks


Azure Questions & Answers - 2

Wednesday, August 26, 2015

1. What is Azure Cloud Service & the usefulness of it?

Cloud service is a term that means more than one thing, but in summary it's a logical group.

There's also Worker and Web Roles that usually are referred as Cloud Service too. So, what is Cloud Service, depends on context.

Cloud Services are ways to combine a set of stateful virtual machines (or web/worker role instances, which are stateless virtual machines) into its own private network, sitting behind a public virtual IP address. Cloud service is a management and security boundary for VMs

Cloud Service also provides optional load-balancing between the virtual machines

Originally, the cloud service was a network isolation container into which compute resources are placed. It is used for Azure PaaS and IaaSv1 resources. Its considered "legacy" and is not present in Azure's IaaSv2 which is based on the new Azure Resource Manager model

v1 is the version of IaaS that was launched in 2012. IaaS v2 uses Azure Resource Manager (ARM) API's

2. What are the different ways in which Traffic Manager decides to which endpoint to route traffic?

  • Round-Robin
  • Failover
  • Performance


3. What is the maximum bandwidth provided by ExpressRoute?

1 Gbps when a Network Service Provider is used and 10 Gbps with an Exchange Service Provider

4. How many data drives can you attach to a Standard_G5 VM (the biggest size in the series)?

64 data drives which can provide the maximum IOPS of  32000 (64 X 500)

5. While considering lifting and shipping existing applications to Azure VMs, what are the challenges to prepare for?

Reliability, availability, security, and performance are all important concerns.

Especially, because Azure provides SLAs only if there are at least two VMs in an Availability Set, to ensure availability, you’ll need to deploy the application to at least two VMs and join them behind a load balancer. This might immediately cause some problems because not all applications are designed for such deployment. For instance, some of the legacy systems are designed to have a single central server that handles all user transactions. When the transactions are distributed to multiple instances, you might have two centers of truth that can’t be reconciled. Data replication and customer partition are two effective approaches in some cases.


6. When you have servers running on both on-premises and the cloud, it’s almost unavoidable that you will experience some performance degradation because of the extra network latency. What code changes would you make to reduce latency?

Common techniques include introducing cache to reduce accesses to databases, using asynchronous IO operations, compressing data, sending deltas and only required data instead of complete data sets, and paging.

7. What is the difference between Upgrade Domain and Fault Domain?

Upgrade domains are similar to Fault domains in function, but they support upgrades rather than failures.

An Upgrade domain is a logical unit of instance separation that determines which instances in a particular service will be upgraded at a point of time

A Fault domain boundary is basically a different hardware rack in the same datacenter. Fault domains don't share a common power source or network switch

8. What is the difference between Access Control Lists & Network Security Groups?

You can use both network Access Control Lists (ACLs) and Network Security Groups (NSGs) to control traffic to your VMs. In either case, the traffic is filtered before it reaches your VM so that your machine doesn’t need to spend extra cycles on packet filtering.

NSGs are different from ACLs in a couple of aspects:
* ACLs are applied to traffic with a specific VM endpoint, whereas NSGs are applied to all traffic
that is inbound and outbound on the VM.
* ACLs are associated to a VM endpoint, whereas NSGs are associated to a VM, or a subnet
within a virtual network.

9. What are the different sources of images for a Azure VM?

  • Azure VM Gallery
  • VM Depot
  • Custom images

10. What is the role of Internal Load Balancers?

ILBs provide load balancing among VMs residing in a Cloud Service or a regional virtual network. ILBs (Internal Load Balancers) are not publicly accessible.

Note - Features of Azure services may change at any time.

ReferenceExam Ref 70-534 Architecting Microsoft Azure Solutions

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This Week I Learned - Week #124

Sunday, August 23, 2015
This Week I Learned -

* Linux now (August 2015) drives about 25 percent of the activity on Azure - Wired

* Cloud computing was invented by Amazon in 2006.  Netflix built its TV and movie business atop the Amazon cloud. Dropbox erected its file-sharing operation there. Google and Microsoft released beta versions of similar cloud services in 2008 — Google App Engine and Windows Azure - Wired

* ..you should think of Docker as a shipping container for software. Just as shipping containers give us a standard pod we can transfer from boat to train to truck, Docker offers a standard means of moving software from machine to machine to machine. If an app needs more computing power—or some of the machines running it quit working—Docker provides a way of easily spreading to new machines - Wired

Hyper-V requires a 64-bit processor that includes Hardware-assisted virtualization & Hardware-enforced Data Execution Prevention (DEP)

* The Hyper-V role is not supported on Windows Azure Virtual Machines. Microsoft supports only specific versions of Microsoft server software within the Azure virtual machine environment.

If your application needs 1 quad core processor in a physical server, you can say that it will need 4 virtual processors as a virtual machine.

* The PDF eBook version of Skype for Business User Tips & Tricks for Anyone is free to download

* The System Information tool (Msinfo32.exe) available with Windows OS. On some older versions of Windows, it cannot be invoked by typing msinfo32.exe at the command line. In such cases, it can be located at this path - c:\program files\common files\microsoft shared\msinfo

* Mark Russinovich, now Microsoft Technical Fellow, completed a computer engineering master’s degree from the Rensselaer Polytechnic Institute in New York and a PhD at Carnegie Mellon, before doing a post-doc at the University of Oregon. He specialized in the design of computer operating systems.

...future patches are going to continue to say nothing more than "This update includes improvements to enhance the functionality of Windows 10."

* ServerWatch ranks Ubuntu as the best in its list of top 10 Linux server operating systems for 2015

* India-born, Britisher, Sir Ronald Ross received the Nobel Prize for Physiology or Medicine in 1902 for his work on malaria.  After two years of research failure, he discovered the presence of the malarial parasite inside the gut of mosquito in 1897 in Secunderabad. It is Italian physician and zoologist Giovanni Battista Grassi who demonstrated that human malarial parasites were transmitted only by female Anopheles. Ross's personal vendetta with G.B. Grassi became a legendary tale in science. Ross carefully saved virtually everything about himself: correspondence, telegrams, newspaper cuttings, drafts of published and unpublished material, and all manner of ephemera

Archibald Campbell brought tea cultivation to Darjeeling

Louis Pasteur created the first vaccines for rabies and anthrax.  He is best known for his invention of the technique of treating milk and wine to stop bacterial contamination, a process now called pasteurization.  Three of his five children died of typhoid before reaching adulthood. These personal tragedies were his motivations for curing infectious diseases. Historical reassessment of Pasteur's notebook revealed that he practiced deception to overcome his rivals.

* "In the field of observation, chance favors only the prepared mind" - Louis Pasteur

JD Salinger ("The Catcher in the Rye"), Anna Sewell ("Black Beauty"),  Margaret Mitchell ("Gone With the Wind") are a few of the most celebrated authors who did not write a second novel

Some tax experts recommend filing Income Tax returns even if you annual income is below the taxable limits so that you can claim a refund in the following cases -
- you have suffered losses from stock market transactions and you want to carry it forward to the next year then you must file refund
- your employer has cut Tax Deducted at Source (TDS)
- you earned some money through freelance work and the company deducted TDS at 10 per cent. Since your income is lower than the taxable limit, you are entitled for refund.
- you are earning rental income of more than Rs 1.8 lakh per year. In this case, the tenant has to deduct TDS. So, while you are entitled to refund, if you have no other source of income, you have to file return to claim the refund

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HOW TO copy a doc / spreadsheet from Google Docs to OneDrive without saving to local computer

1. Open the document or spreadsheet to be copied to OneDrive, within Google Docs / Drive
2. From the menu, choose File > Email as Attachment...

3. In the dialog box that opens, choose to attach the file as .docx or .xlsx as appropriate and email it to your Microsoft account

4. When the email is opened within Outlook.com, click on the button View in OneDrive to view & save that file in OneDrive to view it in Word Online or Excel Online

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Azure Questions & Answers - 1

Saturday, August 22, 2015

1. Name the "kernel" of the Azure Cloud operating system

Fabric Controller (FC). It provisions, stores, delivers, monitors and commands the virtual machines (VMs) and physical servers that make up Azure.

2. Critical business applications require a low RTO & RPO. True or False

True

3. Scaling-out is a preferable scaling method for cloud applications than scaling-up - True or False

True. Scaling up is constrained by what VM sizes are available

4. Azure organizes VM sizes into different machine series. What are they & what is specialty of each series?

  • A series - generic workloads
  • A8-A11 - high performance computing
  • D series - high CPU & high temporary data IO
  • DS series - high I/O workloads
  • G series - high CPU & high memory demands

5. When you create a VM in Windows Azure you are provided with a temporary storage automatically. What is the location of this storage

This temporary storage is “D:” on a Windows VM and it is “/dev/sdb1” on a Linux VM.

6. What is the purpose of temporary storage in VMs?

This temporary storage is used to save the system paging file.

You can also use this drive only to store temporary data, which you can afford to lose at any time.

Like for example: If your workflow involves getting content from the blob, processing it and storing it back to the blob then you could download content to the temporary storage, process the content, then take the processed content and save it back to the blob.

7. When will the data on temporary drive in a VM be lost?

When you resize the VM, when you shutdown or restart your VM, when your VM is moved to a different host server(due to service healing, shutdown and restart), when the host is updated, when the host experiences a hardware failure etc.

8. Is there any cost associated with temporary storage?

The temporary storage provided with each VM has no extra cost associated with it for storage space as well as for transactions.

9. How are VHDs in Azure Storage charged?

VHD's are persisted as page blobs and so you are charged for the space consumed in the blob. 

For Windows Azure Drive storage, you will be billed only for the storage space used by the page blob and the read/write transactions to the page blob. You will not be charged for read transactions that utilize the local drive cache. Windows Azure Drive usage is billed at the same rates as standard Windows Azure Storage and is included with Windows Azure Storage usage in your bill. - Official Azure documentation

10. If I place VMs in different cloud services in Azure, can they still talk to each other?

Yes. All VMs within the cloud service can communicate with each other via the DIP. VMs in different cloud services can communicate via endpoints defined on the cloud service VIP. Although this is fine for limited communications, it isn't efficient.

The better solution is to place the cloud services in a virtual network, which then allows all the VMs in cloud services on the same virtual network to communicate directly using the internal (DIP) addresses

Note - Features of Azure services may change at any time.

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This Week I Learned - Week #123

Sunday, August 16, 2015
This Week I Learned -

* Azure may provision VMs having either AMD or Intel processors. Currently, there is no choice of hardware while creating VMs in Azure. G-series VMs run on hosts with Intel Xeon E5 V3 family processors.

All images and disks in Azure, except the temporary disk, are actually virtual hard disks (VHDs). The virtual hard disks are .vhd files stored as page blobs in a standard or premium storage account in Azure. They can also be fixed, dynamically expanding, or differencing. Azure supports VHD format, fixed disks.

Once a blob is created/uploaded you can't change the blob type.

* AWS EC2 virtual machines use EBS (similar to page blobs) for running disks

You can’t assign more vCPUs to a virtual machine than you have physical cores in your host.

Jeff Bezos believes in data-driven management. Amazon has laid out 14 leadership principles. “Amazon is where overachievers go to feel bad about themselves”. As team members are ranked, and those at the bottom eliminated every year, it is in everyone’s interest to outperform everyone else.

Workday, a human resources software company, makes a product called Collaborative Anytime Feedback that promises to turn the annual performance review into a daily event. One of the early backers of Workday was Jeff Bezos, in one of his many investments. 

The median employee tenure at Amazon is one year, among the briefest in the Fortune 500

Total colorblindness, in which a person sees only black and white, is very rare.

* Hyderabad’s IT workforce has 3.20 lakh professionals. Hyderabad accounts for only 13 per cent of the country’s IT exports against 31 per cent from the Garden City (Bangalore)

* Put your phone on airplane mode & it will charge faster

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