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Apple iPad Success or Failure ?

Wednesday, February 17th, 2010

Apple iPad is the most innovative product launched in Feb,2010. Well, before its growth there are many criticisms and debates about the product. I am giving my views after analysis.

There are very less chances for the product to get failed.  The crispy features in the ipad announces its success and wrote a foreword for the “iPad’s Success Story”

iPad is the super idea  to access the Web,Photos,Videos,E-mail etc.,

Features of  Apple ipad

Safari Browser

The tablet has a large multi-touch screen which has the option to switch to portrait  and landscape view.

Strengths of iPad

No multitasking, no USB port, no Flash, no camera – that’s iPad for you. Still the device has speed, portability, style, simplicity and above all price going for it.

The iPad seems to have come in with a clearcut and flawless strategy to capture the market. By cutting out on expensive features such as the camera, Apple is set to penetrate the market on the price flank.

Price of iPad

The price of iPad starts at $499.  So that a middle class can afford buying it. I accept it is not economic for all. :-)

Great Features of iPad

LED-Backlit IPS Display – This has 9.6 inches of LED display that you can’t image even. So working on this would be great.

Multi-Touch Screen – This is similar to the one we see in iPhone.

Light Weight – Apple iPad weighs just 1.5 pounds and 0.5 inch thin.

Very long battery life – This graphical tablet deserves the long battery life. The battery lasts almost for 10 hours.

Numerous Applications – There are about 140,000 applications available in this great magic box.

You can write and send email, text messages

With the Apple iPad you can store all your information personal or for work.

You can listen to music or watch a movie when you have nothing to do.

And of course you can browse the internet.

Facebook – This comes with you where ever you go. Connect to your friends in one touch.

You Tube -  The iPad has the built in you tube video organiser where you can play videos in landscape mode. In this mode the video automatically switches to fullscreen view.

Handy iPod and iTunes – You can still feel the pleasure of iPod and the power of iTunes. Buletooth headphones are supported.

iBookStore – This is apple’s online bookstore. You can just read or buy books and keep it in your shelf just in one touch.

 

http://www.apple.com/ipad/

Regards,
R.Gopinath

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mysql error #1226 user has exceeded max_questions

Tuesday, January 19th, 2010

Problem Statement:

mysql error #1226

The problem that everyone faces with very old databases. The reason for this error is when the database user connects to the server for several times, there are many possibilities of database lock.

1. The user connection may not have terminated properly.

2. Or the maximum connection limit specified for that particular user may have exceeded from the limit.

To resolve this mysql error #1226. we have to configure the database properly.

Mostly people using the wordpress CMS need to change the wp_options table.

Usually this situation happens sometimes due to server overloading or user exceeding max_connections_per_hour.

Solution:

But there are many instances for us that we can’t wait for such a long time to update the tables and databases and we may need to seek help from others.

During that critical time, this solution helps you much from avoiding the downtime of your website.

Once i faced a similar problem and my website was down for 1 week. It was a drastic situation and i lost all my page rank.

But i came forward with a quick and simple solution.

Follow these simple steps to solve ‘user has exceeded max_questions’ problem

1. Your database must have a user ‘A’ using which you have configured your wordpress blog.

2. Now the problem is that user ‘A’ has exceeded maximum_questions resource (current value: 40)

3.  Create a new user ‘B’ in your database through your domain control panel  and update the same user name you wp-config.php file in  wordpress installation directory.

4.  Now you got the problem fixed in few minutes. It will not disturb the database or the posts you have in your wordpress or phpbb.

For phpbb  users ‘mysql error #1226 user has exceeded max_questions’

1.  Follow the same steps above and update the config.php file in your phpbb installation directory.

The issue is solved.  This may be a simple two-lined solution but powerful.

Keep away your worries and enjoy blogging. if any clarifications revert back to gopi@neuronring.com.

Regards,

R.Gopinath

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Posted in Troubleshooting | No Comments »

High Availability Clustering–Types and Advantages

Tuesday, October 27th, 2009

What does High Availability mean?

In terms of computers HA means a system design protocol which ensures the availability of a resource in a given amount of time or any terms of measurement.

HA-Clustering and Failover

This is a computer cluster implemented for making a resource available all the time or reducing the downtime of the resource. For example, an application server serving the user requests continuously and in come point of time it stopped responding. In that time the users waiting for a response from the server should not get disappointed.

Here comes the clustering technology, the cluster configuration in the network transfers or redirects the user requests to the backup server. This process is called Failover.

High-availability-clustering

High-availability-clustering

The Clustering Software

The clustering software plays main role in the successful functioning of the HA-Clusters. Everyone have a question of who maintains the information and transactions processed by the First Machine.

Yes, the clustering software does that for us. It will copy the last good known configuration from the machine which failed to complete its duty to the machine which is ready to serve for us.

Heart Beat of Clustering

HA clusters use a private Heart-Beat network. This network is responsible for monitoring the health status of all the nodes in the cluster.

HA-Clustering

HA-Clustering-Heart Beat

Split-Brain in Cluster network

The term “Split-Brain” technically explains the following scenario. When all the private network link goes down but the individual cluster nodes are still running, there is a possibility of confusion. Each node in the cluster may think that other node is down and will supply duplicate data. So this is a tedious configure the network to avoid split-brains.

Cluster Node Configurations

 These are the available clustering node configurations

 1. Active/Active – Traffic is directed to another existing node or balanced across all other nodes

2. Active/Passive – A complete new node is served when primary node fails

3.  N+1 – Serving a complete new node in the place of primary node and the new node    in the cluster must be capable of handling any services which the primary node handled with/without any special additional software.

4. N+M – Here more than one dedicated nodes are served for handling failovers.
This   may require high cost and maintenance.

5. N-to-1 – Here the backup node is serving temporarily until the primary node is brought back online. Then the running services are transferred to primary node.

6. N-to-N — A combination of Active/Active and N+M clusters, N to N clusters.

Requirements for a High Availability Clustering Environment

 

The HA-Clustering is widely used technology in Data centers and Industries where adaptive infrastructure is required. This requires high investment hence this is called as costly technology.

Below given are the minimum requirements for setting up a HA Clustered Environment.

  1. You must be having suitable advanced application which is capable to support HA-C. Not all the applications can run in High Availability Environment.
  2. The application should be capable of running its own multiple instances.
  3. The application you are using in HA-C must have command line utility. i.e ability to control the app through command line interface by executing some commands.
  4. The application should have the capability of using Storage Area Network (SAN).

The application must be capable of storing the data in a SAN, so that even a crash occurs the other back-up node can use the saved-state of information.

Applications of HA Clustering Technology

So, where is this clustering more useful and applied ? HA Clustering is used for

1. Critical databases

2. File sharing networks

3. Business Applications

4. E-Commerce Websites

oracle-real-application-clusters-RAC

Some famous HA-Clustering products

Vendor Product Name Supported Platforms
Hewlett-Packard HP ServiceGuard   HP-UX, Linux
IBM High Availability Cluster AIX, Linux
Open –Source Linux-HA   Linux
Microsoft Microsoft Cluster Server (MSCS) Windows server 2008
Red Hat Red Hat Cluster Suite Linux

My next update in HA-Clustering would be about configuring the HA clusters in live environment.

Wait for a couple days….

Regards,
R.Gopinath

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Posted in Unix and Linux | No Comments »

Logical Volume Manager – LVM Configuration,pvcreate,vgdisplay,vgscan,lvcreate

Tuesday, October 20th, 2009

What is  Logical Volume Manager ?

HP-UX LVM is used to manage disk space with special features like mirroring, high availability, stripping, etc. Physical volumes can be organized into a logical volume groups with equal size extent.

Each volume group can have one or more physical volumes. A system can have more than single volume groups. A volume group can be moved from a system to another instead of physical disk.

A volume group can be divided into virtual disks, called logical volumes. A logical volume can span a number of physical volumes or represent only a portion of one physical volume. Disks can be added into logical volumes with different sizes.

The following commands are used to create, display and manipulate the LVM:

1. pvcreate

Creates physical volume to use in logical volume group.

Syntax:  pvcreate -f /dev/rdsk/c2tod1

2. pvdisplay

Displays information about physical volumes in LVM volume group.

Syntax:  pvdisplay /dev/dsk/c2tod1

3. pvmove

Move allocated physical extents frm one LVM physcal volume to another.

Syntax:  pvmove /dev/dsk/c1t0d0 PVG0

4. vgcreate

Creates LVM volume group.

Syntax:  Create a directory for volume group. 

mkdir /dev/vg00 

vgcreate -s 2 /dev/vg00 /dev/dsk/c1t0d0

5. vgdisplay

Display information about LVM volume groups.

Syntax:  vgdisplay -v /dev/vg00

6. vgexport

Export an LVM volume group and its associated logical volumes.

Syntax:  vgexport -v -f vg00.outfile /dev/vg00

7. vgimport

Import an LVM volume group onto the system.

Syntax: vgimport -v /dev/vg00 /dev/dsk/c0t1d0

8. vgextend

Extend an LVM volume group by adding physical volumes.

Syntax:  vgextend /dev/vg00 /dev/dsk/c0t1d0

9. vgreduce

Remove physical volumes from an LVM volume group.

Syntax:  vgreduce /dev/vg00 /dev/dsk/c0t1d0

10. vgremove

Remove LVM logical volume group from system.

Syntax:  vgremove /dev/vg00 /dev/dsk/c0t1d0

11. vgscan

Scans physcal volumes for LVM volume group.

Syntax: vgscan

12. lvcreate

Creates logical volume in LVM volume group.

Syntax: 

lvcreate -L 100 /dev/vg03

13.  lvdisplay

Displays information about logical volumes .

lvdisplay /dev/vg00

14. lvextend

Increase space,mirrors for logical volumes.

lvextend -L 400 /dev/vg03

15.  lvreduce

Reduce number of physical extents, mirrors.

lvreduce -L 50 /dev/vg03

16. lvremove

Remove one or more logical volumes from system.

lvremove -f /dev/vg03

17. lvlnboot

Prepare LVM logical volume to be root, boot, primary swap, or dump volume.

lvlnboot -r /dev/vg00

18. lvrmboot

Remove logical volume link to root, primary swap, or dump volume.

lvrmboot -r /dev/vg00

Regards,
R.Gopinath

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