HDMI monitor blinking (flickering)

I have a dual monitor setup at home, one is connected via HDMI and another one through DVI. A couple days back I noticed that the HDMI monitor was blinking very often, it used to go blank for a couple of seconds but the DVI one just worked fine. According to few forum posts the issue was related to graphics driver but in my case the problem was occurring on both Windows 7 as well as ArchLinux so I ruled out the driver issues, my Arch installation uses open source drivers.

Somewhere it was also mentioned that it might have something to do with "ground loop", you can read more about it on Wikipedia. Then I realized I had recently changed the power cords for the HDMI monitor, and the power cord which was in use did not have an earthing pin (3rd big pin in a plug), it looked like this:

When I replaced the 2-pin plug power chord with a 3-pin plug one (the one with the earthing pin) the blinking problem disappeared. So I guess it was related to earthing but not necessarily to ground loop.

Ebay India Orders Fuck Up

I purchased a 24'' monitor to replace my 4 year old 19'' monitor from eBay on 13th of December. The estimated delivery date mentioned on the product page was 17th Dec. On 17th Dec I received this email from eBay:

MC011 XXXXXXX: Update- Error in payment mode details updated with the courier

Hello, Thank you for shopping with eBay We have noticed that due to a system bug there are few transactions where a wrong information about the payment mode has been updated in the system. You might receive SMS alert or an Emails asking you to keep the cod amount ready with you at the time of delivery. Request you to kindly ignore this SMS/Email and not to give any cod amount at the time of delivery if you have made payment of your transaction by using Debit/Credit card or via Net banking. Kindly be rest assured this issues has been addressed and resolved, the correct information of payment has been shared with the courier to avoid confusion at the time of delivery. If the courier executive is asking you to pay the cod amount you can refuse the payment and expect the product to be delivered in the next 2-3 working days without the cash being collected. If your transaction is getting returned due to this reason, you will get the refund of your transaction as per Paisa pay timelines. We sincerely regret for the inconvenience caused to you and also appreciate your cooperation and understanding at this time. Regards eBay India

Next day I received this SMS from BlueDart courier company:

Ebay order will reach thru BlueDart Awb xxxxxxxxx on or after 19-DEC-13.Kindly keep Cash Rs.xxxxx ready.

Today (20th December) morning I received an email saying:

A refund has automatically been initiated on item "BenQ GL2450HM LED Monitor" on 20-Dec-2013 since our shipping partner has not confirmed pickup of your shipment from the seller within the timelines.

I called up the seller and asked about this refund thing, the seller did not have any clue about it. He told me that the item was already shipped. Around 3 PM the courier company guys appeared with the monitor at my doorstep and asked me to pay the whole amount again which I had already paid while placing the order. I tried to explain them that it was a prepaid item not a Cash On Delivery, it was of no use. Those guys took the monitor back and updated the status as: "Cnee Refused To Accept Shipment".
In the evening I got another email saying:

"Your refund request has been put on hold by PaisaPay on 20-Dec-13 as the seller has appealed against this refund"

I checked my account page and here is how it looked:

Notice the dates underlined by the orange line, they are all future dates. How on earth a company like ebay can fuck up so much and at so many levels ??
First they fucked up the order payment mode then gave wrong information about the shipment and now all the dates celebrating Christmas already.
This was indeed an enlightening experience, will probably avoid going to ebay any more. Its already 8th day since I placed the order and customer care guy told me to wait till 25th Dec. WOW!!

PITA 6: PHP Warning: Unknown: open(/var/lib/php/session/...., O_RDWR) failed: Permission denied (13) ...

Recently I compiled php 5.3 on my Centos 5.x machine, everything worked fine until I noticed that the HTTP session was not getting created.
I checked the apache error logs and found this php warning getting repeated:

 PHP Warning:  Unknown: open(/var/lib/php/session/...., O_RDWR) failed: Permission denied (13) in Unknown on line 0

I tried to look for the solution on the net, couldn't find a proper solution except someone saying that apache sever should have write access to the session directory (/var/lib/php/session in my case). I did: 

chmod 777 /var/lib/php/session

and restarted the http server, no warning this time in the error logs, everything started working as expected.

My ls -l looks like following:

drwxrwxrwx 2 root apache 270336 Feb 23 14:27 session

Resolving grub rescue issue after Windows 8 installation

The issue occurs when you try to upgrade your Windows 7 to Windows 8 and have installed a Linux version (e.g. Ubuntu) in the past, parallel to Windows 7. The grub rescue screen appears just after first restart and it doesn't let you boot into the Windows. In my case the text looked like this:

error: unknown filesystem.
grub rescue>

This happens because grub can not find the Linux partition, which you may have deleted earlier (just by formatting the Linux disk partition). First you can try all these options:

1. Repair Windows start-up using Windows 7 installation DVD.
2. Using command prompt option with W7 installation DVD to fix master boot record (MBR) [Link] & [Link]
3. Try removing Grub using Ubuntu live CD/DVD [Link]
4. Use Ubuntu tool "Boot-Repair" [Link]

If any of the above mentioned option did not work, then use the Ubuntu live CD/DVD to install Boot-Repair, after installation click on "Create a BootInfo summary":

This will analyze all the partitions' boot information and create a report, you'll have to access this report using the URL given by this program. The URL will look like: http://paste.ubuntu.com/(a_number)/

The report is divided in many sections, what you should be looking at is the block where you can find an entry mentioning grub.

For example in my case the grub entry was located on the partition sda3:

sda3:__________________________________________________________________________
    File system:       vfat
    Boot sector type:  Unknown
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:  
    Boot files:        /EFI/Boot/bootx64.efi /EFI/ubuntu/grubx64.efi 
                       /EFI/Microsoft/Boot/bootmgfw.efi 
                       /EFI/Microsoft/Boot/bootmgr.efi 
                       /EFI/Microsoft/Boot/memtest.efi

In you case grub boot file may be located on a different partition, mount that partition into newd directory using command (in ubuntu live cd/dvd session):

sudo mount /dev/sda3 /newd

go to the newd directory and then EFI by typing:

cd /newd/EFI/

remove the whole ubuntu directory using command:

sudo rm -r ubuntu

End the live Ubuntu session and restart. If you can boot into the Windows then it worked!! Otherwise look for other solutions on the Google (one of them was: re-installing the Ubuntu again, hence fixing the Grub).

PITA 5: NetBeans 6.8 Beta & Glassfish v3 Problems!

Installed NetBeans 6.8 Beta last week, firstly I had some trouble creating virtual server:

Cause: Unable to create a new instance of 'com.sun.faces.application.resource.ResourceHandlerImpl': java.lang.NullPointerException

had to use default virtual server.

and now after a glassfish update last night, I am not able to build, deploy and undeploy any web app on glassfish. Keep getting this in server log:

org.apache.catalina.LifecycleException: PWC2769: Manager has not yet been started
at org.apache.catalina.session.StandardManager.stop(StandardManager.java:892)
at org.apache.catalina.core.StandardContext.stop(StandardContext.java:5383)
at com.sun.enterprise.web.WebModule.stop(WebModule.java:531)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:5211)
at com.sun.enterprise.web.WebModule.start(WebModule.java:500)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:928)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:912)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:694)
at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1932)
at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1604)
at com.sun.enterprise.web.WebApplication.start(WebApplication.java:90)
at org.glassfish.internal.data.EngineRef.start(EngineRef.java:126)
at org.glassfish.internal.data.ModuleInfo.start(ModuleInfo.java:241)
at org.glassfish.internal.data.ApplicationInfo.start(ApplicationInfo.java:236)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:337)
at com.sun.enterprise.v3.server.ApplicationLoaderService.processApplication(ApplicationLoaderService.java:340)
at com.sun.enterprise.v3.server.ApplicationLoaderService.postConstruct(ApplicationLoaderService.java:163)
at com.sun.hk2.component.AbstractWombImpl.inject(AbstractWombImpl.java:174)
at com.sun.hk2.component.ConstructorWomb$1.run(ConstructorWomb.java:87)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.hk2.component.ConstructorWomb.initialize(ConstructorWomb.java:84)
at com.sun.hk2.component.AbstractWombImpl.get(AbstractWombImpl.java:77)
at com.sun.hk2.component.SingletonInhabitant.get(SingletonInhabitant.java:58)
at com.sun.hk2.component.LazyInhabitant.get(LazyInhabitant.java:107)
at com.sun.hk2.component.AbstractInhabitantImpl.get(AbstractInhabitantImpl.java:60)
at com.sun.enterprise.v3.server.AppServerStartup.run(AppServerStartup.java:236)
at com.sun.enterprise.v3.server.AppServerStartup.start(AppServerStartup.java:128)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:457)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:401)
at org.jvnet.hk2.osgiadapter.HK2Main.start(HK2Main.java:125)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:915)
at org.jvnet.hk2.osgimain.Main.start(Main.java:140)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1077)
at org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:264)
at java.lang.Thread.run(Thread.java:619)
|#]
org.apache.catalina.LifecycleException: java.lang.NullPointerException
at org.apache.catalina.core.StandardContext.start(StandardContext.java:5216)
at com.sun.enterprise.web.WebModule.start(WebModule.java:500)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:928)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:912)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:694)
at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1932)
at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1604)
at com.sun.enterprise.web.WebApplication.start(WebApplication.java:90)
at org.glassfish.internal.data.EngineRef.start(EngineRef.java:126)
at org.glassfish.internal.data.ModuleInfo.start(ModuleInfo.java:241)
at org.glassfish.internal.data.ApplicationInfo.start(ApplicationInfo.java:236)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:337)
at com.sun.enterprise.v3.server.ApplicationLoaderService.processApplication(ApplicationLoaderService.java:340)
at com.sun.enterprise.v3.server.ApplicationLoaderService.postConstruct(ApplicationLoaderService.java:163)
at com.sun.hk2.component.AbstractWombImpl.inject(AbstractWombImpl.java:174)
at com.sun.hk2.component.ConstructorWomb$1.run(ConstructorWomb.java:87)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.hk2.component.ConstructorWomb.initialize(ConstructorWomb.java:84)
at com.sun.hk2.component.AbstractWombImpl.get(AbstractWombImpl.java:77)
at com.sun.hk2.component.SingletonInhabitant.get(SingletonInhabitant.java:58)
at com.sun.hk2.component.LazyInhabitant.get(LazyInhabitant.java:107)
at com.sun.hk2.component.AbstractInhabitantImpl.get(AbstractInhabitantImpl.java:60)
at com.sun.enterprise.v3.server.AppServerStartup.run(AppServerStartup.java:236)
at com.sun.enterprise.v3.server.AppServerStartup.start(AppServerStartup.java:128)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:457)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:401)
at org.jvnet.hk2.osgiadapter.HK2Main.start(HK2Main.java:125)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:915)
at org.jvnet.hk2.osgimain.Main.start(Main.java:140)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1077)
at org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:264)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
at org.glassfish.deployment.common.ClassDependencyBuilder.getAnnotatedClasses(ClassDependencyBuilder.java:57)
at org.glassfish.deployment.common.ClassDependencyBuilder.computeResult(ClassDependencyBuilder.java:41)
at org.glassfish.web.loader.ServletContainerInitializerUtil.checkAgainstInterestList(ServletContainerInitializerUtil.java:405)
at org.glassfish.web.loader.ServletContainerInitializerUtil.getInitializerList(ServletContainerInitializerUtil.java:313)
at org.apache.catalina.core.StandardContext.callServletContainerInitializers(StandardContext.java:5258)
at com.sun.enterprise.web.WebModule.callServletContainerInitializers(WebModule.java:551)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:5190)
... 37 more
|#]
java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: java.lang.NullPointerException
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:932)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:912)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:694)
at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1932)
at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1604)
at com.sun.enterprise.web.WebApplication.start(WebApplication.java:90)
at org.glassfish.internal.data.EngineRef.start(EngineRef.java:126)
at org.glassfish.internal.data.ModuleInfo.start(ModuleInfo.java:241)
at org.glassfish.internal.data.ApplicationInfo.start(ApplicationInfo.java:236)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:337)
at com.sun.enterprise.v3.server.ApplicationLoaderService.processApplication(ApplicationLoaderService.java:340)
at com.sun.enterprise.v3.server.ApplicationLoaderService.postConstruct(ApplicationLoaderService.java:163)
at com.sun.hk2.component.AbstractWombImpl.inject(AbstractWombImpl.java:174)
at com.sun.hk2.component.ConstructorWomb$1.run(ConstructorWomb.java:87)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.hk2.component.ConstructorWomb.initialize(ConstructorWomb.java:84)
at com.sun.hk2.component.AbstractWombImpl.get(AbstractWombImpl.java:77)
at com.sun.hk2.component.SingletonInhabitant.get(SingletonInhabitant.java:58)
at com.sun.hk2.component.LazyInhabitant.get(LazyInhabitant.java:107)
at com.sun.hk2.component.AbstractInhabitantImpl.get(AbstractInhabitantImpl.java:60)
at com.sun.enterprise.v3.server.AppServerStartup.run(AppServerStartup.java:236)
at com.sun.enterprise.v3.server.AppServerStartup.start(AppServerStartup.java:128)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:457)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:401)
at org.jvnet.hk2.osgiadapter.HK2Main.start(HK2Main.java:125)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:915)
at org.jvnet.hk2.osgimain.Main.start(Main.java:140)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1077)
at org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:264)
at java.lang.Thread.run(Thread.java:619)
|#]
java.lang.Exception: java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: java.lang.NullPointerException
at com.sun.enterprise.web.WebApplication.start(WebApplication.java:118)
at org.glassfish.internal.data.EngineRef.start(EngineRef.java:126)
at org.glassfish.internal.data.ModuleInfo.start(ModuleInfo.java:241)
at org.glassfish.internal.data.ApplicationInfo.start(ApplicationInfo.java:236)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:337)
at com.sun.enterprise.v3.server.ApplicationLoaderService.processApplication(ApplicationLoaderService.java:340)
at com.sun.enterprise.v3.server.ApplicationLoaderService.postConstruct(ApplicationLoaderService.java:163)
at com.sun.hk2.component.AbstractWombImpl.inject(AbstractWombImpl.java:174)
at com.sun.hk2.component.ConstructorWomb$1.run(ConstructorWomb.java:87)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.hk2.component.ConstructorWomb.initialize(ConstructorWomb.java:84)
at com.sun.hk2.component.AbstractWombImpl.get(AbstractWombImpl.java:77)
at com.sun.hk2.component.SingletonInhabitant.get(SingletonInhabitant.java:58)
at com.sun.hk2.component.LazyInhabitant.get(LazyInhabitant.java:107)
at com.sun.hk2.component.AbstractInhabitantImpl.get(AbstractInhabitantImpl.java:60)
at com.sun.enterprise.v3.server.AppServerStartup.run(AppServerStartup.java:236)
at com.sun.enterprise.v3.server.AppServerStartup.start(AppServerStartup.java:128)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:457)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:401)
at org.jvnet.hk2.osgiadapter.HK2Main.start(HK2Main.java:125)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:915)
at org.jvnet.hk2.osgimain.Main.start(Main.java:140)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1077)
at org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:264)
at java.lang.Thread.run(Thread.java:619)
|#]
java.lang.Exception: java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: java.lang.NullPointerException
at com.sun.enterprise.web.WebApplication.start(WebApplication.java:118)
at org.glassfish.internal.data.EngineRef.start(EngineRef.java:126)
at org.glassfish.internal.data.ModuleInfo.start(ModuleInfo.java:241)
at org.glassfish.internal.data.ApplicationInfo.start(ApplicationInfo.java:236)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:337)
at com.sun.enterprise.v3.server.ApplicationLoaderService.processApplication(ApplicationLoaderService.java:340)
at com.sun.enterprise.v3.server.ApplicationLoaderService.postConstruct(ApplicationLoaderService.java:163)
at com.sun.hk2.component.AbstractWombImpl.inject(AbstractWombImpl.java:174)
at com.sun.hk2.component.ConstructorWomb$1.run(ConstructorWomb.java:87)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.hk2.component.ConstructorWomb.initialize(ConstructorWomb.java:84)
at com.sun.hk2.component.AbstractWombImpl.get(AbstractWombImpl.java:77)
at com.sun.hk2.component.SingletonInhabitant.get(SingletonInhabitant.java:58)
at com.sun.hk2.component.LazyInhabitant.get(LazyInhabitant.java:107)
at com.sun.hk2.component.AbstractInhabitantImpl.get(AbstractInhabitantImpl.java:60)
at com.sun.enterprise.v3.server.AppServerStartup.run(AppServerStartup.java:236)
at com.sun.enterprise.v3.server.AppServerStartup.start(AppServerStartup.java:128)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:457)
at com.sun.enterprise.module.bootstrap.Main.launch(Main.java:401)
at org.jvnet.hk2.osgiadapter.HK2Main.start(HK2Main.java:125)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:915)
at org.jvnet.hk2.osgimain.Main.start(Main.java:140)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:640)
at org.apache.felix.framework.Felix.activateBundle(Felix.java:1700)
at org.apache.felix.framework.Felix.startBundle(Felix.java:1622)
at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1077)
at org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:264)
at java.lang.Thread.run(Thread.java:619)
|#]
|#]
|#]

For now I am using Tomcat and waiting for final release of glassfish v3.
Also I keep getting following error all the time whenever I try to edit a jsp file in NB:

java.lang.NullPointerException
at org.netbeans.modules.web.core.jsploader.BaseJspEditorSupport$4.propertyChange(BaseJspEditorSupport.java:176)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:276)
at org.openide.text.CloneableEditorSupport.firePropertyChange(CloneableEditorSupport.java:527)
at org.openide.text.CloneableEditorSupport.fireDocumentChange(CloneableEditorSupport.java:2320)
at org.openide.text.CloneableEditorSupport.closeDocument(CloneableEditorSupport.java:2201)
at org.openide.text.CloneableEditorSupport.access$2500(CloneableEditorSupport.java:123)
at org.openide.text.CloneableEditorSupport$StrongRef.run(CloneableEditorSupport.java:2681)
at org.netbeans.modules.openide.util.ActiveQueue.run(ActiveQueue.java:64)
[catch] at java.lang.Thread.run(Thread.java:619)

Hope this too gets resolved in final 6.8 release.

PITA 4: MySQL Error Messages

Today while connecting to my DB Server, I got a strange error message:

Got error 28 from storage engine

Tried to check the .err file located in var/lib/mysql (Xubuntu), couldn't open the file, when checked, the file size was more than 50GB.

This was the reason of the above error (No free space on the disk to write!). Stopped MySQL server and deleted the .err file. After starting the server I checked the file for errors and found this error repeated for millions times:

091026 ***** InnoDB: Error: page ***** log sequence number * *********
InnoDB: is in the future! Current system log sequence number 0 330424282.
InnoDB: Your database may be corrupt or you may have copied the InnoDB
InnoDB: tablespace but not the InnoDB log files. See
InnoDB: http://dev.mysql.com/doc/mysql/en/backing-up.html for more information.

Since I copied the complete data folder from one computer to another, the log files for InnoDB got corrupted. I could not restore them.

The only option I had to avoid any data loss or corruption was to change the Engine type to MyISAM, which doesn't look for log files and can be repaired with less effort.

PITA 3: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

I was trying to update around 70k records in a MySQL table through a loop, and kept getting the following exception after 16k+ records:

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
Last packet sent to the server was 0 ms ago.

Tried everything which I could get on the web, but nothing happened. Few suggestions which I found on the web are:

1. replace localhost with 127.0.0.1 in MySQL connection string... In some cases this works because Windows Defender removes localhost entry from C:\Windows\system32\drivers\etc\hosts file therefore MySQL won't be able to resolve the host and throw that exception.

2. modify registry to connect from TCP ports greater than 5000... this also didn't work for me, you can see the opened connection by typing the command netstat -b.
Details about this are given here http://support.microsoft.com/kb/196271

3. add wait_timeout = X in my.ini (or my.cnf on *nix env.)... this will help if you have problems with MySQL itself, for that check MySQL error log located in mysql Data directory. If you have any errors about connections setting wait_timeout may help, but in my case there are no errors from MySQL site.

How did I resolve it??... Instead of processing all the records in one execution I processed only 1000 records at a time.

However the exact reason is still unknown.

PITA 2: Edit my.cnf file in Ubuntu

I tried to bind the local machine's global address to allow the remote connections for mysql (5.1) in my.cnf file, it kept giving me:

Error: no write permission for file "my.cnf"

tried edit etc/mysql/my.cnf and gedit etc/mysql/my.cnf also tried to change the permission of the file and the mysql folder by chmod with no success.

Until I found out putting sudo is necessary before every command if the user account is not root.
http://ubuntuforums.org/showthread.php?p=7077569

Used sudo gedit etc/mysql/my.cnf and it worked.