OBJECTIVES: I will be able to describe how fault tolerance is built into the internet during today's class.

CALENDAR:

WORDS FOR TODAY:

I STRONGLY URGE YOU TO START A DECK OF FLASH CARDS HERE

• abstraction (a layer between hardware/software hidden to the user)
• innovation: "A new or improved idea, device, product, etc
• prototype: "A proof of concept"
• bandwidth: Transmission capacity measure by bit rate
• latency: Time it takes for a bit to travel from its sender to its receiver.
• protocol: A set of rules governing the exchange or transmission of data between devices
• router: "Traffic Cop"
• packets: Discreet blocks of internet traffic sent between computers & servers as directed by routers.
• Port - one of 64,000 'doors' available to access your computer from the outside world
• Server - A computer designed to process specific data requests from users
• TCP - Transfer Control Protocol - Provides connection information to a specific port on a specific server on the interweb
• IP - Internet Protocol - Provides Name/Address information to a specific server on the interweb
• HTTP: Hyper Text Transfer Protocol
• Root Servers (Manage the DNS system)
• DNS - Domain Name System -- The service that translates URLs to IP addresses
• Redundancy (Backups and Many Paths)
• FAULT TOLERANCE

WORK O' THE DAY: 

Oh and before we get started, please go to your "MY AP" page. If you are planning on taking the test, please verify the check box is selected. If you are not planning on taking the test, please make sure that text box is NOT selected. Thank you.

Gentle reminder, the deadline is November 8th (next week!)

The industry standard for a measurement of the reliability of hard drives is something called the 'mean time to failure' (mttf) rate. That measure indicates how long we can expect a hard drive to last before it fails.

We can go right to the manufacturer and get that data. Let's look HERE

In preparing for today's class, I did some research and found the mechanical hard drives typically have a *shorter* mttf than solid state hard drives that have fewer mechanical parts.

Please go and find the mttf rates for either a Toshiba SDD (with the same or similar physical size and storage capacity). Let's compare.

Now let's sit back and take a gander at this. If a HDD has a mttf of a million hours that's over 100 years. Let's say we have a cabinet full of 10 rows of HDD and each row has 20 HDD and each of those we can expect to fail in 100 years, it sure sounds like we shouldn't worry about any of them failing.... so problem solved, right?

If we look at THIS data from a cloud computing outfit we find definitive evidence that HDDs DO fail. What gives?

Please discuss

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Having said that, there is a fly in the ointment here-- which is to say that SDD drives tend to wear down faster if they experience a higher number of read/write processes.

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What are other examples of Fault Tolerance in internet infrastructures? Please discuss.

What about Fault Tolerance in the PSD tech infrastructure?

What about Fault Tolerance in your home?