3. Availability of a Service
One standard feature of Cloud Computing service
is availability "anytime and anywhere“.
Fast response time
Low downtime
A quasi tagline: five nines (99.999%) availability
7. ID Reported Summary Organization Services ID Reported Summary Organization Services
Companies left staggering or totally Amazon Elastic
Amazon Web Heroku Unable to Provision New Dedicated
1 4/21/2011 knocked out because of server problems Compute Cloud 30 3/2/2011 Heroku Cloud Hosting
Services Databases
in the Amazon datacenter (Amazon EC2)
Connectivity Issues Affect External
2 4/21/2011 PlayStation Network outages Sony PlayStation Network 31 2/28/2011 GoGrid GoGrid
GoGrid CRM
Twitter Experiences Delays in Delivering Twitter.com and API Experience Elevated
3 3/25/2011 Twitter, Inc. Twitter 32 2/26/2011 Twitter, Inc. Twitter
to Facebook and SMS Error Rates
Twitter.com and API Experience Stability
4 3/25/2011 Heroku Users Experience HTTP 503 Errors Heroku Cloud Hosting 33 2/24/2011 Twitter, Inc. Twitter
Issues
Twitter.com Experiences Unspecified
5 3/25/2011 Twitter Experiences Tweet Delivery Delay Twitter, Inc. Twitter 34 2/23/2011 Twitter, Inc. Twitter
Problems and Load Issues
Heroku Shared Database Experienced GoGrid Customers Experience Private
6 3/25/2011 Heroku Cloud Hosting 35 2/22/2011 GoGrid GoGrid
Hardware Failure Network Connectivity Issues
Heroku Users Unable to Provision New
7 3/25/2011 Heroku Cloud Hosting 36 2/21/2011 Heroku Database Does Not Accept Commands Heroku Cloud Hosting
Dedicated Databases
8 3/23/2011 Netflix Streaming and Web Site Down Netflix Netflix Streaming 37 2/21/2011 Heroku Slow Responses May Cause Timeouts Heroku Cloud Hosting
Heroku New Relic Deployment Notification
9 3/21/2011 Heroku Cloud Hosting 38 2/18/2011 Twitter Image Upload Disabled Twitter, Inc. Twitter
Outage
Network Connectivity Issues Cause
10 3/18/2011 Heroku Cloud Hosting 39 2/15/2011 Twitter API Redirects a Blank Page Twitter, Inc. Twitter
Increased Errors on Heroku
Code Error Causes Blogger Dashboard
11 3/17/2011 Google, Inc. Blogger 40 2/15/2011 Tweets Delayed in Displaying to Timeline Twitter, Inc. Twitter
Outage
Personal Tweets Delayed on Home Unspecified Errors Cause Elevated Errors
12 3/17/2011 Twitter, Inc. Twitter 41 2/15/2011 Twitter, Inc. Twitter
Timelines Rate in Twitter
Some outages in 2011
Multiple Twitter Functions Experience
13 3/16/2011 Twitter, Inc. Twitter 42 2/13/2011 Heroku Unable to Create New Applications Heroku Cloud Hosting
Outage
Heroku Experiences Increased Application
14 3/16/2011 Heroku Shared Database Offline Heroku Cloud Hosting 43 2/9/2011 Heroku Cloud Hosting
Latency
15 3/15/2011 Heroku Experiences Unspecified Errors Heroku Cloud Hosting 44 2/8/2011 Heroku Experiences Poor Performance Heroku Cloud Hosting
16 3/14/2011 Heroku Experiences Elevated Error Rates Heroku Cloud Hosting 45 2/2/2011 Rackspace Support Experiences Delays Rackspace, Inc. Support
Heroku Customers Unable to Deploy New The Rackspace
17 3/13/2011 Heroku Cloud Hosting 46 2/1/2011 DNS Issue Causes MySQL Server Outage Rackspace, Inc.
Applications Cloud
Rackspace Email &
GoGrid Experiences Network Latency Rackspace SAT and DFW Mail Relays
18 3/12/2011 GoGrid GoGrid 47 2/1/2011 Rackspace, Inc. Apps (formerly
Issues Blacklisted
Mailtrust)
Twitter Search Queries Experience GoGrid Portal Issue Prevent Cloud Server
19 3/11/2011 Twitter, Inc. Twitter 48 1/24/2011 GoGrid GoGrid Portal
Slowness and Failure Configuration
Heroku Users Unable to Access Database Issue Prevents Heroku App
20 3/11/2011 Heroku Cloud Hosting 49 1/21/2011 Heroku Cloud Hosting
Application Logs Creation
Jive Software Down Due to Hardware
21 3/11/2011 Heroku Experiences Elevated Error Rates Heroku Cloud Hosting 50 1/14/2011 Jive Software Jive Engage
Failure
Heroku Experiences Unspecified Elevated Bank of America Experiences Timeout
22 3/11/2011 Heroku Cloud Hosting 51 1/14/2011 Bank of America Online Banking
Error Rates Issues
Heroku Application Creation and Logging
23 3/10/2011 Heroku Cloud Hosting 52 1/14/2011 SalesForce CS0 Outage Salesforce.com Salesforce.com
Offline
Twitter Users Not Receiving Email Cloud Hosting 8.5
24 3/7/2011 Twitter, Inc. Twitter 53 1/14/2011 Heroku Unable to Provision New Databases Heroku
Notifications hours
Heroku Unable to Provision Dedicated Wikipedia and Associated Projects Wikimedia Wikipedia.com Wiki
25 3/7/2011 Heroku Cloud Hosting 54 1/13/2011
Databases Experience Short Term Outage Foundation, Inc. media Projects
Twitter.com Add Your Location Function GoGrid Portal Access and IP Assignment GoGrid
26 3/6/2011 Twitter, Inc. Twitter 55 1/12/2011 GoGrid
Temporarily Disabled Outage Portal GoGrid API
GoGrid Network Issues Affects Public and Heroku Load Balancer Causes Intermittent
27 3/4/2011 GoGrid GoGrid 56 1/12/2011 Heroku Cloud Hosting
Private Networks Request Failures
GoGrid Customers Unable to Add VPS Microsoft
28 3/4/2011 GoGrid GoGrid 57 1/4/2011 Hotmail Loses Emails for Two Days Hotmail
8. Possible Solution
• A physical view:
installment of more
servers/ datacenters
• A software view: employment of better design
for the server architecture and server
management system
9. A Netflix solution
Multiple Region Support
Avoid EBS Dependencies
Stateless Services
Graceful Degradation
"N+1" Redundancy
from The Netflix Tech Blog
10. Scalable Storage in the Cloud
Persistent (scalable ) storage enables that a named set of data items that come into
existence through explicit creation, persist through temporary failures of the system,
until they are explicitly deleted.
15. NoSQL
Seif Haridi 2011
NoSQL is a current trend in non-relational databases.
Data is stored and retrieved using a single key: may lack
table schemas, may lack ACID properties (no transactions),
no join operations.
Main advantages are excellent performance, with good
horizontal scalability and elasticity (ideal fit to clouds)
while SQL databases have good vertical scalability but
are not elastic.
