Back to blogging in honor of RHEL 6…
Finally, the latest major version of RHEL is announced today.
Here is the press release for it: http://www.redhat.com/about/news/prarchive/2010/new-standard.html and the release notes are available at http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Release_Notes/
More importantly all the new stuff can be found here: http://www.redhat.com/rhel/server/details/
There are a lot of improvements and new features all of which I think will make Red Hat Linux a rock solid operating system for the data center.
Yesterday I took the RH302 Red Hat Certified Engineer Lab Exam and passed it.
I have been certified as a Red Hat Certified Engineer.
Below are my exam results:
Dear ORHAN BIYIKLIOGLU:
The results of your RHCE Certification Exam are reported below. The
RHCE Certification Exam allows candidates to qualify for the
Red Hat Certified Engineer (RHCE) and Red Hat Certified Technician
(RHCT) certificates. Please note that the RHCE designation is
understood to both include and supersede the RHCT designation.
RHCE requirements: score of 70 or higher on RHCT components (100 points)
score of 70 or higher on RHCE components (100 points)
RHCT requirement: score of 70 or higher on RHCT components (100 points)
RHCT components score: 100.0
RHCE components score: 100.0
RHCE Certification: PASS
Congratulations — you are now certified as a Red Hat Certified
crs_stat is the Oracle Clusterware command that provides status information for resources on the cluster nodes.
It provides NAME,TYPE,TARGET and STATE information for each configured resource in the following format by default:
STATE=ONLINE on node1
The awaited Ubuntu version 9.10 aka Karmic Koala is released today.
It is available for download here.
Some of the notable changes are:
- Linux kernel 2.6.31
- GNOME 2.28
- Mozilla Firefox 3.5
- OpenOffice.org 3.1.1
- Empathy Instant Messenger replacing Pidgin for instant messaging tasks
- Ubuntu One client for the Ubuntu One, personal cloud platform that provides 2GB of storage to keep you files, notes and contacts
- Ubuntu Software Center is the new graphical utility for package management which replaces the traditional GNOME Add/Remove tool
Also there are some important feature changes like:
- ext4 is the new default filesystem used for new installations
- GRUB2 is the new default boot loader for new installations
- Upstart is the new startup mechanism that replaces the venerable System-V init
These features seem to help achieve faster boot times.
The Ubuntu variants Kubuntu, Xubuntu, Edubuntu, Mythbuntu, and Ubuntu Studio are also updated to version 9.10
Release Notes contains a list of known problems with this new release but there is no show stopper so far.
See here for some screenshots.
FTP server processes of most UNIX systems records user login and logout events in the login log file (wtmpx/wtmps). These files keep track of all login/logout events and typically grow without bounds.
If your systems are receiving large number of ftp connections than ftp records dominates the log files and makes it difficult to track shell logins via last command and other utilities. Also the size of the wtmpx/wtmps files will grow huge and take a lot of disk space.
Thankfully ftpd command on Solaris 10 and HP-UX 11.23/11.31 systems has a command line switch that disables recording of ftp login/logout sessions. You must add the “-W” on the command line while starting the ftpd process.
To achieve this:
You can use the inetadm command to configure inetd-controlled services on Solaris 10 systems.
Issue the following inetadm command to append “-W” to the command line of the svc:/network/ftp:default service. You must refresh the service definition using the svcadm command to make the change take effect.
inetadm -m svc:/network/ftp:default exec="/usr/sbin/in.ftpd -a -W"
svcadm refresh svc:/network/ftp:default
inetd configuration is done using the good old inetd.conf file on HP-UX systems.
You can edit the /etc/inetd.conf file and append the “-W” at the end of the ftp line.
You must run the inetd -c command to make the inetd deamon to reload the configuration and make your changes take effect.
ftp stream tcp6 nowait root /usr/lbin/ftpd ftpd -l -W
If you are using ASMLIB library to label ASM disks on Red Hat Enterprise Linux 5.X or SuSE Linux Enterprise Server 10/11 systems with EMC PowerPath as your multipathing software you may encounter the following error while running the oracleasm createdisk command:
#/etc/init.d/oracleasm createdisk DATA01 /dev/emcpowera1
Marking disk "/dev/emcpowera1" as an ASM disk:
asmtool: Device "/dev/emcpowera1" is not a partition
This is due to the EMC PowerPath bug #285242 which makes it to not properly support the sd_getgeo() i/o calls that oracleasm makes, as mentioned in the Oracle Metalink document 469163.1 and EMC Powerlink document emc203137
The workaround to overcome this problem is to use the asmtool command with “-a force=yes” option.
#/usr/sbin/asmtool -C -l /dev/oracleasm -n DATA01 -s /dev/emcpowera1 -a force=yes
asmtool: Device "/dev/emcpowera1" is not a partition
asmtool: Continuing anyway
asmtool will also complain that the device is not a partition but it will put the asmlib header on the device and create the related device file under /dev/oracleasm/disks/ directory. However it will leave the device file with root:root as the owner and group. Restarting the asmlib service will solve this problem.
service oracleasm restart
The actual solution has arrived with PowerPath for LINUX 5.3.1 for RHEL and PowerPath for LINUX 5.3.2 for SLES 11. After updating to this release oracleasm createdisk command works flawlesly as expected.
#oracleasm createdisk DATA02 /dev/emcpowerb1
Writing disk header: done
Instantiating disk: done
There are some other very important bugs solved in Powerpath releases 5.3 and 5.3 SP1 like “Dynamic addition of large number of LUNs may result in a host hang” and “PowerPath: emcpmgr processes are causing high load during startup” so there is good reason to update to the latest Powerpath release.
Let’s begin with a very good description of the term System Administrator.
The following description is taken from the book “UNIX Administration Guide for System V” by Rebecca Thomas and Rik Farrow (Pearson PTR; 2 edition, June 1989)
The system administrator is one of the users of a system, and something more. The administrator wears many hats, as knowledgeable user of UNIX commands, as an operator of system hardware, and as a problem solver. The administrator is also called upon to be an arbitrator in human affairs. A multiuser computer is like a vast imaginary space where many people work and utilize the resources found there. The administrator must be the village elder in this space and settle the disputes that may arise with, hopefully, the wisdom of Solomon.
Very well stated and still valid after 20 years!