Troubleshooting and Error Messages Tips for Platform and OpenLava

Troubleshooting and Error Messages Tips for Platform. But it can be used for OpenLava. Do take a look and digest.

Troubleshooting and Error Messages

udev: renamed network interface eth0 to eth2

I was encountering this error when I start the network

# dmesg |grep eth0 
udev: renamed network interface eth0 to eth2

This occurs when you clone or change the NIC hardware and the OS still retain the old interface information in /etc/udev/rules.d/70-persistent-net.rules.

Just delete /etc/udev/rules.d/70-persisitent-net.rules and reboot the system so the Linux can rebuild the /etc/udev/rules.d/70-persistent-net.rules that match the replaced NIC hardware.

# rm  /etc/udev/rules.d/70-persistent-net.rules
# reboot

Failed to conect to FastX Server

Do take a look at Failed to start a secure connection to the server

Basically, to fix this issue, run the command from your linux machine:

# killall fastx_server 

Relaunch the FastX Client

No irq handler for vector on CentOS 6

If you are getting error messages on the /var/log/messages on your CentOS 6. You may want to see Redhat Bugzilla "No irq handler for vector" error, sluggish system"

Aug 20 11:22:58 node1 kernel: do_IRQ: 2.135 No irq handler for vector (irq -1)

Step 1: Edit Grub Bootloader. Add the pci=nomsi,noaer to the end of the kernel options

# vim /boot/grub.menu.1st

default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS 6 (2.6.32-504.el6.x86_64)
        root (hd0,0)
        kernel /vmlinuz-2.6.32-504.el6.x86_64 ro root=/dev/mapper/vg_cherry-lv_root rd_NO_LUKS  KEYBOARDTYPE=pc KEYTABLE=us LANG=en_US.UTF-8 rd_NO_MD rd_LVM_LV=vg_cherry/lv_root SYSFONT=latarcyrheb-sun16 crashkernel=128M rd_LVM_LV=vg_cherry/lv_swap rd_NO_DM rhgb quiet pci=nomsi,noaer
        initrd /initramfs-2.6.32-504.el6.x86_64.img

Step 2: Disable irqbalance daemon

# service irqbalance stop
# chkconfig --levels 2345 irqbalance off

Step 3: Reboot the System

# reboot 

References:

1.  Red Hat Bugzilla – Bug 225399
2.  No irq handler for vector

Using Python 2 on JupyterHub

If you are installing and configuring JupyterHub, do take a look

1. Basic Setup and Configuration of JupyterHub with Python-3.4.3 

By default, JupyterHub uses Python 3.3. However you may want to use Python-2 on JuypterHub. You may want to take a look at Basic Setup and Configuration of JupyterHub with Python-3.4.3

Step 1: Install latest version of Python-2
You may want to see Installing and Compiling Python 2.7.8 on CentOS 5. You can apply this for CentOS 6

Step 2: Remember to install iPython2 and iPython[notebook] on Python-2
Do take a look at Installing scipy and other scientific packages using pip3 for Python 3.4.1 for some similar ideas

 Step 3: Install Python KernelSpec for Python 2

# /usr/local/python-2.7.10/bin/python2 -m IPython kernelspec install-self
# /usr/local/python-3.4.3/bin/python3 -m IPython kernelspec install-self

Step 4: Restart JupytHub

# juypterHub

Fixing Rsync out of memory Issues

If you are doing rsync and you encountered this error like rsync out of memory, you may want to take a look.a this article (Rsync out of memory? Try this...). Need to add an additional parameter (--no-inc-recursive) to the rsync commands.

According to the article, the the out of memory failure occured when  rsync attempts to load all the filenames and info in to RAM at startup. For example,

# rsync -lH -rva --no-inc-recursive --progress gromacs remote_server:/usr/local

References:

1. Commonly Used rsync Arguments

Cannot retrieve metalink for repository: epel. Please verify its path and try again

I was doing a yum install and I encountered an error

# yum install libstdc++-4.4.7-16.el6.x86_64
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
Error: Cannot retrieve metalink for repository: epel. 
Please verify its path and try again

The correct fix is to update your SSL certificates.

# yum upgrade ca-certificates --disablerepo=epel -y

Yum install again. You should be able to work.

# yum install libstdc++-4.4.7-16.el6.x86_64

Error when installing libXrender for CentOS 6

If you do encountered an issue such as this. Apparently, there is a incompatibility between llibXi-1.7.2-2.,/pre>2.el6.i686 != libXi-1.6.1-3.el6.x86_64

# yum install libXrender

Error:  Multilib version problems found. This often means that the root
       cause is something else and multilib version checking is just
       pointing out that there is a problem. Eg.:

         1. You have an upgrade for libXrender which is missing some
            dependency that another package requires. Yum is trying to
            solve this by installing an older version of libXrender of the
            different architecture. If you exclude the bad architecture
            yum will tell you what the root cause is (which package
            requires what). You can try redoing the upgrade with
            --exclude libXrender.otherarch ... this should give you an error
            message showing the root cause of the problem.

         2. You have multiple architectures of libXrender installed, but
            yum can only see an upgrade for one of those arcitectures.
            If you don't want/need both architectures anymore then you
            can remove the one with the missing update and everything
            will work.

         3. You have duplicate versions of libXrender installed already.
            You can use "yum check" to get yum show these errors.

       ...you can also use --setopt=protected_multilib=false to remove
       this checking, however this is almost never the correct thing to
       do as something else is very likely to go wrong (often causing
       much more problems).

       Protected multilib versions: libXrender-0.9.8-2.1.el6.i686 != libXrender-0.9.7-2.el6.x86_64
 You could try using --skip-broken to work around the problem

To resolve the issue, you have to install libXrender-0.9.8-2.1.el6.x86_64

# yum install libXrender-0.9.8-2.1.el6.x86_64

Finally, do a

# yum install libXrender

Error when installing libXi for CentOS 6

If you do encountered an issue such as this. Apparently, there is a incompatibility between llibXi-1.7.2-2.,/pre>2.el6.i686 != libXi-1.6.1-3.el6.x86_64

# yum install libXi 

Error:  Multilib version problems found. This often means that the root
       cause is something else and multilib version checking is just
       pointing out that there is a problem. Eg.:

         1. You have an upgrade for libXi which is missing some
            dependency that another package requires. Yum is trying to
            solve this by installing an older version of libXi of the
            different architecture. If you exclude the bad architecture
            yum will tell you what the root cause is (which package
            requires what). You can try redoing the upgrade with
            --exclude libXi.otherarch ... this should give you an error
            message showing the root cause of the problem.

         2. You have multiple architectures of libXi installed, but
            yum can only see an upgrade for one of those arcitectures.
            If you don't want/need both architectures anymore then you
            can remove the one with the missing update and everything
            will work.

         3. You have duplicate versions of libXi installed already.
            You can use "yum check" to get yum show these errors.

       ...you can also use --setopt=protected_multilib=false to remove
       this checking, however this is almost never the correct thing to
       do as something else is very likely to go wrong (often causing
       much more problems).

       Protected multilib versions: libXi-1.7.2-2.2.el6.i686 != libXi-1.6.1-3.el6.x86_64
 You could try using --skip-broken to work around the problem

To resolve the issue, we have to do a

# yum install libXi-1.7.2-2.2.el6.x86_64

and you will see quite a list of updates to some core libraries. Finally, you can do a

# yum install libXi 

Error when installing libstc++ for CentOS 6

If you do encountered an issue such as this. Apparently, there is a incompatibility between libstdc++-4.4.7-16.el6.i686 != libstdc++-4.4.7-11.el6.x86_64.

# yum install libstdc++.so.6

Resolving Dependencies
--> Running transaction check
---> Package libstdc++.i686 0:4.4.7-16.el6 will be installed
--> Finished Dependency Resolution
Error:  Multilib version problems found. This often means that the root
       cause is something else and multilib version checking is just
       pointing out that there is a problem. Eg.:

         1. You have an upgrade for libstdc++ which is missing some
            dependency that another package requires. Yum is trying to
            solve this by installing an older version of libstdc++ of the
            different architecture. If you exclude the bad architecture
            yum will tell you what the root cause is (which package
            requires what). You can try redoing the upgrade with
            --exclude libstdc++.otherarch ... this should give you an error
            message showing the root cause of the problem.

         2. You have multiple architectures of libstdc++ installed, but
            yum can only see an upgrade for one of those arcitectures.
            If you don't want/need both architectures anymore then you
            can remove the one with the missing update and everything
            will work.

         3. You have duplicate versions of libstdc++ installed already.
            You can use "yum check" to get yum show these errors.

       ...you can also use --setopt=protected_multilib=false to remove
       this checking, however this is almost never the correct thing to
       do as something else is very likely to go wrong (often causing
       much more problems).

       Protected multilib versions: libstdc++-4.4.7-16.el6.i686 != libstdc++-4.4.7-11.el6.x86_64
You could try using --skip-broken to work around the problem
** Found 1 pre-existing rpmdb problem(s), 'yum check' output follows:
1:emacs-23.1-25.el6.x86_64 has missing requires of libotf.so.0()(64bit)

To resolve the issues, do a

# yum install libstdc++-4.4.7-16.el6.x86_64

and you will see quite a list of updates to some core libraries. Finally, you can do a

# yum install libstdc++