Compling ANTLR 2.7.7 on CentOS 6

November 26, 2014, 12:08 am

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What is ANTLR?
ANTLR, ANother Tool for Language Recognition, (formerly PCCTS) is a language tool that provides a framework for constructing recognizers, compilers, and translators from grammatical descriptions containing Java, C#, C++, or Python actions. ANTLR provides excellent support for tree construction, tree walking, and translation. There are

Step 1:Download ANTLR 2.7.7

Step 2: Untar ANTLR-2.7.7

# tar -zxvf antlr-2.7.7
# antlr-2.7.7

Step 3: For RHEL and CentOS, edit the source file /root/antlr-2.7.7/lib/cpp/antlr/CharScanner.hpp

# vim /root/antlr-2.7.7/lib/cpp/antlr/CharScanner.hpp

Add the following into the CharScanner.hpp file


Step 4: Compile the antlr-2.7.7

# ./configure --prefix=/usr/local/antlr2.7.7 --disable-examples
# make -j 8
# make install

References:

1. http://sourceforge.net/p/nco/discussion/9830/thread/08ae0201

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Compiling udunits-2.1.24 on CentOS 6

November 26, 2014, 12:53 am

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The UDUNITS package supports units of physical quantities. Its C library provides for arithmetic manipulation of units and for conver

Step 1: Download udunits-2.1.24 from ftp://ftp.unidata.ucar.edu/pub/udunits/

Step 2:Untar and compile

# tar -zxvf udunits-2.1.24
# cd udunits-2.1.24
# ./configure --prefix=/usr/local/udunits-2.1.24 CC=gcc CXX=g++
# make 
# make install

Understanding Formatted Capacity versus Unformated Capacity

November 26, 2014, 7:51 pm

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Have you wondered why Formatted Capacity is lesser than the Unformated Capacity of a Hard Disk. Do take a look at this article Formatted capacity confusion clarified

Storage hardware is using the base 10 system and software is using the base 2 system. So no storage is actually lost, it is just a question of how the information is represented.

Alert-Out-of-Band Security Updates for Adobe Flash Player

November 26, 2014, 8:41 pm

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Adobe has released security updates for Adobe Flash Player 15.0.0.223 and earlier versions for Windows and Macintosh and Adobe Flash Player 11.2.202.418 and earlier versions for Linux.

Update Adobe Flash Player to the latest version

References:

1. http://helpx.adobe.com/security/products/flash-player/apsb14-26.html

Yum giving "Cannot retrieve metalink for repository: epel" Error for CentOS 6

December 4, 2014, 1:18 am

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When I was updating yum install or doing yum update on CentOS 6.4, I received an error "Cannot retrieve metalink for repository: epel"

The error is because of the scripts in the epel.repo under the mirrorlist pointing to https instead of http. If you amend it to http, the epel repo will work

 At /etc/yum/repos.d/epel.repo, change to

[epel]
.....
.....
mirrorlist=http://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch

[epel-debuginfo]
.....
.....
mirrorlist=http://mirrors.fedoraproject.org/metalink?repo=epel-debug-6&arch=$basearch

References:

1. CentOS 6.3 Instance Giving "Cannot retrieve metalink for repository: epel" Error

Changing local and group ownership

December 7, 2014, 8:39 am

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I usually use the following commands to change ownership of a file or directory

# chown username.usergroups myfile.

But sometimes the users name contain a fullstop in the username. In that case, the following

# chown user.name:usergroups myfile

LRZ HPC Cluster Storage Systems

December 8, 2014, 9:39 pm

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I thought I pen down the LRZ HPC Cluster Storage Systems usage of NetApp and GPFS File System to support their computing needs.

Storage Systems
SuperMUC has a powerful I/O-Subsystem which helps to process large amounts of data generated by simulations.

Home file systems
Permanent storage for data and programs is provided by a 16-node NAS cluster from Netapp. This primary cluster has a capacity of 2 Petabytes and has demonstrated an aggregated throughput of more than 10 GB/s using NFSv3. Netapp's Ontap 8 "Cluster-mode" provides a single namespace for several hundred project volumes on the system. Users can access multiple snapshots of data in their home directories.

Data is regularly replicated to a separate 4-node Netapp cluster with another 2 PB of storage for recovery purposes. Replication uses Snapmirror-technology and runs with up to 2 GB/s in this setup.

Storage hardware consists of >3400 SATA-Disks with 2 TB each protected by double-parity RAID and integrated checksum


Work and Scratch areas
For highest-performance checkpoint I/O IBM's General Parallel File System (GPFS) with 10 PB of capacity and an aggregated throughput of 200 GB/s is available. Disk storage subsystems were built by DDN.

References:

1.  SuperMUC Petascale System

Encountering 'Write Failed: Broken Pipe" suring SSH connection on CentOS

December 10, 2014, 9:01 am

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I encountered this error Write Failed: Broken Pipe" during SSH connection. From what I know, it is caused by the Linux Server severing connections that have been idle too long ago.

To solve the issues, you can do the following

1. At your Linux Server Side, you can configure

# vim /etc/ssh/sshd_config

.....
ClientAliveInterval 60
.....

2. At your Client Side

# vim ~/.ssh/config 

.....
ServerAliveInterval 60
.....

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Red Hat Atomic and Containers

December 14, 2014, 8:54 pm

≫ Next: NetApp SteelStore Cloud Integrated Storage Appliance

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Red Hat and Containers

Articles

1. Small footprint, big impact: Red Hat Enterprise Linux 7 Atomic Host Beta now available
2. Splitting the Atom: Recapping the First Atomic Application Forum
3. Containers – There’s No Going It Alone

Atomic Video

1.  Red Hat Enterprise Linux 7 Atomic Host & Containers

Blog About Atomic Performance

1.  Performance Testing Red Hat Enterprise Linux 7 Atomic Host Beta on Amazon EC2

NetApp SteelStore Cloud Integrated Storage Appliance

December 15, 2014, 4:55 am

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Taken from NetApp SteelStore

Quick Overview

Use the NetApp® SteelStore™ cloud integrated storage appliance to leverage public and private cloud as part of your backup and archive strategy.

Features (from the website) includes

• Integrates with all leading backup solutions and all major public and private cloud providers.
• Offers complete, end-to-end security for data at rest and in flight using FIPS 140-2 certified encryption.
• Uses efficient, variable-length inline deduplication and compression, reducing storage costs up to 90%.
• Delivers fast, intelligent local backup and recovery based on local storage.
• Vaults older versions to the cloud, allowing for rapid restores with offsite protection.
• Supports policy-based data lifecycle management.
• Scales to an effective capacity of 28PB per appliance.

Technical Specification

Intel NIC driver causing multicast flooding (intermittent wired network disconnection)

December 19, 2014, 2:12 am

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Symptom:
The symptom can range from random disconnection to slowness in the entire school/building wired network. Eventually, the cause of this problem was found to be due to intel-chipset nic card (Intel I2xx/825xx series) sending out erratic & massive multicast traffic, causing flooding of the network and high CPU on the switches. The below link are some url which describe the same problem faced by other user environment:


Resolution:
The recommended step to resolve this problem is to upgrade the intel nic card driver to version 19.0 and above.


References:

1. IPv6 multicast flood during sleep from i217-LM
2. ICMPv6 'Multicast Listener Report' messages are flooding the local network 
3. ICMPv6 'Multicast Listener Report' messages flooding the local network

Using log collector in RHEV 3.3 and above to collect full log

December 22, 2014, 12:02 am

≫ Next: Displaying SPICE on the VM network for RHEV 3.4

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The Log Collector Utility for RHEV 3 is located in /usr/bin/rhevm-log-collector and is provided by the rhevm-log-collector package installed on the RHEV manager system.

 1. To collect all the information, use command

# engine-log-collector
INFO: Gathering oVirt Engine information...
INFO: Gathering PostgreSQL the oVirt Engine database and log files from localhost...
Please provide the REST API password for the admin@internal oVirt Engine user (CTRL+D to skip):
About to collect information from 1 hypervisors. Continue? (Y/n): y
INFO: Gathering information from selected hypervisors...
INFO: collecting information from 192.168.50.56
INFO: finished collecting information from 192.168.50.56
Creating compressed archive...

2. To collect information from selected hosts ending with ending in .11 and .15

# engine-log-collector --hosts=*.11,*.15

3. To collect information from the RHEV-M only

# engine-log-collector --no-hypervisors

References

1. https://access.redhat.com/solutions/61546

Displaying SPICE on the VM network for RHEV 3.4

December 22, 2014, 7:39 pm

≫ Next: cannot change directory to /home/user1. Permission denied on NFS mount

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For more information, do take a look at my blog Displaying SPICE on the VM network for RHEV 3.4

The key issue is that after after selecting the network to house the "Display Network", do remember to boot all the VMs

cannot change directory to /home/user1. Permission denied on NFS mount

December 24, 2014, 11:41 am

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If you encountered the "cannot change directory to /home/user1. Permission denied on NFS mount" when you do a su --login user1. Do check the base directory permission. If the owner and group /home is root.root, do remember to chmod 755

# ls -ld /home
drwx------ 7 root root 8192 Dec 22 15:13 home

Change the permission to

# chmod 755 /home
drwxr-xr-x 7 root root 8192 Dec 22 15:13 home

Checking for Torque Server Version Number

December 24, 2014, 7:55 pm

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To check Torque Version Number, do issue the command

# qstat --version
Version: 4.2.7
Commit: xxxxxxxxxxxxxxxxxxxxxx

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Forcibly kill or purge the Job in the Torque Scheduler

December 29, 2014, 11:30 pm

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When there is a job stuck and cannot be remove by a normal qdel, you can use the command qdel -p jobid. Do note that this command should be used when there is no other way to kill off the job in the usual fashion especially if the compute node is unresponsive.

# qdel -p jobID

References:

1. [torqueusers] qdel will not delete

Kano - Make Machine Yourself.

January 4, 2015, 5:57 pm

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Kano is powered by the Raspberry Pi Model B and  comes with color coded accessories packed in a nifty and good-looking box. The accessories includes

1. Green Wi-Fi dongle; 
2. Red Power Supply
3. Yellow HDMI cable
4. Orange Keyboard
5. Transparent Kit Box
6. Raspberry Pi Model B (ARM 700MHz CPU and 512MB RAM)
7. DIY Speaker
8. Manual with a story-like instruction.
9. SD Card preloaded with Kano OS.
10. Low Price of US$149.99

Checking for Constant Time Stamp Counter

January 6, 2015, 8:03 am

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A Constant Time Stamp Counter is included in more recent Intel Processors (TSC) to reads at the processor's maximum rate regardless of the actual CPU running rate. While this makes time keeping more consistent, but it can skew benchmarks, where a certain amount of spin-up time is spent at a lower clock rate before the OS switches the processor to the higher rate. For more information on Time Stamp Counter, do look at Time Stamp Counter (wikipedia)

To check whether your CPU support TSC, you can issue the command

# grep -q constant_tsc /proc/cpuinfo && echo "Constant TSC detected" || echo "No Constant TSC Detected"

Compiling and Configuring Python 3.4.1 on CentOS

January 13, 2015, 8:41 pm

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Step 1: Remember to turn on RPMForge and EPEL Repository. For more information on repository, see Repository of CentOS 6 and Scientific Linux 6 

Step 2: Download Python-3.4.1 from the Python Download Page

Step 3: Install Prerequisite Software

# yum install openssl-devel bzip2-devel expat-devel gdbm-devel readline-devel sqlite-devel

Step 4: Configure and Build

# cd /installation_home/Python-3.4.1
# ./configure --prefix=/usr/local/python-3.4.1
# make
# make install

Step 5: Check that scripts query the correct interpreter:

#/usr/local/python3/bin/python3

Step 6: Install Scientific Components (Optional: If you requires it) Scipy Stack (for scientific packages in python)

# yum install numpy scipy python-matplotlib ipython python-pandas sympy python-nose

Step 7: Install Python Modules (whatever you need. Here is an example)

# /usr/local/python-3.4.1/bin/pip3 install networkx

Cannot set user id: Resource temporarily unavailable while trying to login or su as a local user in CentOS

January 13, 2015, 10:08 pm

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If you encounter this error while logging on or su --login as a user,

"cannot set user id: Resource temporarily unavailable" while trying to login or su as a local user.

In CentOS 6, the reason for this error is that the the user’s the number of executing threads has reached the nproc resource limit. You can solve the issues

You can edit /etc/security/limits.d/90-nproc.conf which is

# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.

*          soft    nproc     1024
user1       soft    nproc    10240

More Information:

1. Cannot set user id: Resource temporarily unavailable while trying to login or su as a local user in CentOS