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April 04, 2008 07:04 PM
April 04, 2008 04:00 PM
Paul Frields, Fedora Project Leader, asks:
Fedora is being used in a hundred thousand interesting places out in the real world.
* At NASA to do analysis that makes future space exploration safer.
* In studies to improve development for children with Down’s Syndrome (trisomy 21).
* At Creative Commons, to promote open content discovery, creation, and remixing.
* Powering distribution of food to the needy in Mexico.
We want to hear a story about how YOU use Fedora to do something interesting. Enriching. Educational. Enhancing. At work or in your community. How did Fedora help you achieve something special? Just reply in a comment to [his] blog.
April 03, 2008 04:21 PM
Note: This article assumes that you are already familiar with Red Hat® Network (RHN) Satellite server and its applications.
Red Hat Network Satellite server allows users to locally host subscribed content from Red Hat Network and custom content in user-managed channels. An example configuration could include a server syncing content updates directly from RHN, while another mission-critical server could be disconnected from the external network, yet still receive updates via manual syncing. In the latter case, these offline servers must be manually updated regularly. Since content updates cannot be synced directly from rhn.redhat.com, RHN Satellite provides two options for our users:
1. Channel dump ISOs hosted on RHN, per Satellite release.
2. RHN-Satellite-Exporter tool running locally on a RHN Satellite server
To Illustrate this, consider the following setup:
In purely disconnected environments, servers don’t have direct access to RHN to synchronize content. Channel dump media are the primary source for content updates in such cases. As a service to our disconnected RHN Satellite customers, Red Hat provides channel dump media with a base channel dump per channel, supplemented with an incremental dump for every release update. This content can either be sent to customers from Red Hat or downloaded from rhn.redhat.com.
In an isolated Satellite environment, there is often a disconnected Satellite as well as a connected Satellite, as shown in the figure above. In this case, the user already has the updated content on their connected Satellite through Satellite-sync across the network. They don’t have to go to RHN to download channel dump ISOs and re-sync their disconnected satellites.
A tool called Satellite exporter extracts the content and generates its own local channel dumps. Exporter queries the connected Satellite database and exports all the content for a given channel from the database and file system on the Satellite server where the content resides. Content type supported includes channels, channel families, package metadata, RPMs, errata, kickstart files and kickstart trees.
For rhn-Satellite-exporter to work as expected, make sure that:
Let’s work with an example to demonstrate how exporter can be utilized to its maximum potential.
I’m a Satellite administrator with two RHN Satellites. I choose one to be a connected server communicating with RHN and syncing content updates directly over the network. The other is a mission-critical server that I prefer to keep isolated—it is disconnected completely from the outside network for security reasons.
The goal as a Satellite Administrator is to keep the disconnected servers updated. To achieve this, you will make use of the connected Satellite server, which already has content synced from RHN.
First, find out what channel content is available for the connected server to pull down from the connected Satellite. List the channels available with the following command:
[root@connected ~]# rhn-satellite-exporter --list-channels --db=rhnsat/****@rhnsat Channel List: B = Base Channel C = Child Channel B rhel-i386-server-5 C rhel-i386-server-vt-5 C rhn-tools-rhel-i386-server-5 B rhel-i386-as-4 C rhn-tools-rhel-4-as-i386
The example above gives all available channels on the connected server that are being synced from RHN. Lets choose to export rhel-i386-server-5 and its child channels, rhel-i386-server-vt-5 and rhn-tools-rhel-i386-server-5.
Now export the base channel content for the specified channels. Each content type is categorized and dumped as shown below. Multiple channels can be exported at the same time with multiple -c or –channel options. This combines all the channel data and dumps it under the directory specified.
If –end-date is not specified, it defaults to the current export date as end-date. The –db option directs the tool to access the source Satellite database to extract the requested content.
1. Create a directory for all the exported content:
[root@connected ~]# mkdir /tmp/dumps
2. Export base channel content:
[root@connected ~]# rhn-satellite-exporter --db=rhnsat/*****@rhnsat --dir=/tmp/dumps -c rhel-i386-server-5 -c rhel-i386-server-vt-5 -c rhn-tools-rhel-i386-server-5 --debug=5
Exporting incremental channel content (new in Satellite 5.1):
[root@connected ~]# rhn-satellite-exporter --db=rhnsat/*****@rhnsat --dir=/tmp/dumps/ --start-date=20071206000000 --end-date=20080206000000 -c rhel-i386-server-5 -c rhel-i386-server-vt-5 -c rhn-tools-rhel-i386-server-5 --debug=5
So, from the given Satellite server, get all the content for channel rhel-i386-server-5 and its child channels and dumps it under the directory /tmp/dumps/. Content under the directory is dumped into different content types, like so:
[root@connected ~]# ls -l /tmp/dumps/total drwxr-xr-x 2 root root 4096 Nov 11 02:30 arches drwxr-xr-x 2 root root 4096 Nov 11 02:30 blacklists drwxr-xr-x 2 root root 4096 Nov 11 02:30 channel_families drwxr-xr-x 3 root root 4096 Nov 11 02:30 channels drwxr-xr-x 12 root root 4096 Nov 11 02:47 errata drwxr-xr-x 4 root root 4096 Nov 11 02:47 kickstart_files drwxr-xr-x 2 root root 4096 Nov 11 02:47 kickstart_trees drwxr-xr-x 102 root root 4096 Nov 11 02:44 packages drwxr-xr-x 102 root root 4096 Nov 11 02:30 packages_short drwxr-xr-x 102 root root 4096 Nov 11 02:31 rpms
3. To exclude specific content types from the content dump, use –no- option. This is available for rpms, packages, errata, and kickstart trees. For example, if you want to exclude rpms from the rhel-i386-server-5 dump:
[root@connected ~]# rhn-satellite-exporter -c rhel-i386-server-5 --dir /tmp/dumps --no-rpms
Once we have all the content exported to a directory, we have multiple ways to make this content accessible to our disconnected satellites. The most common method is to burn the exported content onto CD or DVD media and carry it to your remote disconnected Satellite servers. Exporter has options to package the content into ISOs suitable for burning on CD or DVD. This can be achieved using the –make-iso= option.
For CD ISOs:
[root@connected ~]# rhn-satellite-exporter --db=rhnsat/rhnsat@rhnsat --dir=/tmp/ --start-date=20060106000000 -c rhel-i386-server-5 --debug=5 --make-iso=cd
For DVD ISOs:
[root@connected ~]# rhn-satellite-exporter --db=rhnsat/rhnsat@rhnsat --dir=/tmp/ --start-date=20060106000000 -c rhel-i386-server-5 --debug=5 --make-iso=dvd
This should create a Satellite-isos/ directory under the –dir specified, dumping the ISOs into that directory along with MD5SUM manifest for all the ISOs.
[root@connected ~]# ls -ld /tmp/dumps/satellite-isos/* -rw-r--r-- 1 root root 63 Nov 15 16:46 /tmp/dumps/Satellite-isos/MD5SUM -rw-r--r-- 1 root root 656816128 Nov 15 16:43 /tmp/dumps/Satellite-isos/rhn-export-20071115.0-01.iso
Now that we have the CD ISOs, burn them onto a CD:
[root@connected ~]# cdrecord -v -pad speed=1 dev=0,0,0 /tmp/dumps/satellite-isos/rhn-export-20071115.0-01.iso
This process of generating the channel content essentially remains the same for any channel and any amount of content. Its easy to setup a cron job to generate this content as frequently as it is needed.
We can now move the channel content created on the connected Satellite onto the disconnected server.
1. Create a mount point to mount the media:
[root@disconnected ~]# mkdir /mnt/dumps
2. Mount the content onto the disk:
[root@disconnected ~]# mount -t iso9660,udf /dev/cdrom /mnt/dumps
3. Check to see if the mounted channel dumps have the correct content:
[root@disconnected ~]# satellite-sync --mount-point=/mnt/dumps –list-channels
4. Use Satellite-sync to point to the above mount point on disk and sync down the channel content from the dumps:
[root@disconnected ~]# satellite-sync --mount-point=/mnt/dumps -c rhel-i386-server-5
Satellite-sync may take some time to complete based on how much content is being synced. Once this step is finished, our disconnected Satellite is all set with the required updated content. Repeat this process as frequently as possible to keep the disconnected servers up-to-date.
This article gives an overview of the multiple ways to populate content on a disconnected RHN Satellite server. It demonstrates exporting content using rhn-Satellite-exporter, packaging content as ISO images, burning them to media, and populating disconnected satellites. Rhn-satellite-exporter is a very powerful tool with a diverse set of options that make content portability between Satellites simple and effective.
Pradeep Kilambi is a Software Engineer and RHCT/RHCE primarily working on RHN Satellite Client/Server Development. In his spare time, he’s also a dedicated Python hacker and open source advocate.
April 02, 2008 09:06 PM
Release Found:Red Hat Cluster Suite 4 update 6
In Red Hat Cluster Suite 4 update 6, the running of system-config-cluster will abort with following error messages or similar:
[root@dhcp-1-170 ~]# system-config-cluster Traceback (most recent call last): File "/usr/sbin/system-config-cluster", line 52, in ? from ConfigTab import ConfigTab File "/usr/share/system-config-cluster/ConfigTab.py", line 27, in ? from ConfigTabController import ConfigTabController File "/usr/share/system-config-cluster/ConfigTabController.py", line 35, in ? from FaildomController import FaildomController File "/usr/share/system-config-cluster/FaildomController.py", line 213 if val == "Yes" or val == "yes" or val="1": ^ SyntaxError: invalid syntax
This is a known issue. At the time this article is written, this bug is under QA process, it will be fixed in next version of Red Hat Cluster Suite.
To work around this issue, please open the file /usr/share/system-config-cluster/FaildomController.py with an editing tool( such as vi, gedit, or similar ), and find line 213 of this file. This line should be read as follows:
if val == "Yes" or val == "yes" or val="1":
Modify the line to:
if val == "Yes" or val == "yes" or val == "1":
Save the modified file and re-execute the system-config-cluster and it will work.
April 01, 2008 04:35 PM
1. First delete the password lists for all profiles on the machine.
del c:windows*.pwl
2. From the command line:
REGEDIT /s \MY_PDCnetlogonnocache.reg
This will run regedit with no program output and a registry input file named nocache.reg, which looks like this:
REGEDIT4 [HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionPoliciesNetwork] "DisablePwdCaching"=dword:00000001
3. Save that as plain text and name it nocache.reg.
Following these steps will greatly increase the security of your Windows 9x machines.
(Ed. note 4/4/08: This was posted for April Fool’s Day.)
March 31, 2008 09:42 PM
No, hardware must meet certain requirements to support full virtualization in Red Hat Enterprise Linux 5. For x86_64-based systems, the processor must support Intel VT-x or AMD-V technology. For Itanium2-based systems, the system must use a Montecito (or newer) processor.
In addition to CPU support, the system BIOS must also support full virtualization. Please contact the system vendor to determine if the BIOS supports full virtualization.
(Note that if this Knowledgebase article was linked from a system listing on the Red Hat Hardware Catalog, the system in question does not support full virtualization.)
March 28, 2008 06:00 PM
Today’s OOXML vote isn’t complete yet, but while you’re waiting for the news, here’s what we’ve been looking at on the web this week:
March 27, 2008 04:38 PM
We got the chance to talk to a lot of developers at JBoss World, including Mark Proctor. In case you don’t know the name, he’s the leader of the Drools project, also known as JBoss Rules to the enterprise folks.
In this segment, we asked what it’s like to be a developer for a project that’s part of the Service Oriented Architecture: how it’s integrated with that philosophy, uses in the real world, and what the future of Drools/ JBoss Rules is.
March 26, 2008 05:36 PM
In 60 countries around the world, 200 teams have organized activities for today, the first Document Freedom Day. It’s a day of grassroots effort (based on the model of Software Freedom Day) to promote and build awareness for the relevance of free document formats and open standards.
Things you can do
Previous RHM articles about ODF
March 25, 2008 06:09 PM
Release Found: Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 4 Update 5
Conga is a web user interface that provides remote management to add and delete cluster nodes, add and delete users along with their privileges. It also provides the capability to remotely configure high-availability and storage clusters. luci maintains a database that stores all cluster and nodes registered to the luci server. It also stores information on all users that are allowed to access those clusters and nodes.
It is ideal to backup the luci database after successfully configuring the cluster infrastructure. The luci_admin backup command backups the luci database and stores the backup data file as /var/lib/luci/var/luci_backup.xml.
Meanwhile, run luci_admin restore to recover the luci database from a backup copy. Only use the luci_admin command when the luci daemon is not running.
March 24, 2008 08:10 PM
Contributing author: Jonathan Robie
You may have read our background article about ODF and OOXML and why Red Hat believes OOXML should not be approved as an ISO standard. This time, we focus on how the standardization process has been compromised at ISO.
ISO’s JTC-1 directives were designed to provide a fair, consensus-based way to design standards that are portable, interoperable, and adaptable to all languages and cultures. The OOXML proposal has suffered from two basic problems: (1) voting irregularities, and (2) the use of a fast-track process for a complex, new, large specification that has not received adequate industry review. The resulting specification was driven almost exclusively by one vendor, has not achieved industry consensus, and has had thousands of issues logged against it, largely due to issues involving implementability, portability, and interoperability. Although resolutions have been proposed for many of the issues that have been raised, there is virtually no time to review these resolutions to determine whether they fix the problems. And the voting irregularities have raised serious issues with the fairness of the process.
For a standards body to have credibility, the procedures it follows need to be credible. ISO’s JTC-1 directives say that the “objective in the development of International Standards should be the achievement of consensus between those concerned rather than a decision based on counting votes.”1 Clearly, there has been no achievement of consensus regarding the adoption of OOXML as a standard, and therefore ISO has turned to a voting process.
We believe that the flaws in the ISO voting process for OOXML are so serious that they must be addressed in order to maintain ISO’s credibility as a standards body. For a standards body to review a proposal adequately and achieve consensus, the participants need to be involved in the entire review process, not merely show up to cast a vote.
Unfortunately, the ISO voting process is not restricted to those who have participated in the past.2 Thirty-six new countries joined the JTC-1 technical committee–just in time for the OOXML vote3– and 90% of these voted in favor of the OOXML proposal. Only 36% of the original membership voted in favor of approving OOXML as a standard.
Allegations have been made that Microsoft encouraged new countries to join the JTC-1, or to upgrade their status (from O-status to P-status) to influence the vote. Contrary to what has been demonstrated, the JTC-1 directives say that the “objective in the development of International Standards should be the achievement of consensus between those concerned rather than a decision based on counting votes.”4
Before an individual country votes in the ISO process, it holds a vote within its own national body. An employee of Microsoft Sweden admitted to offering incentives to business partners to encourage them to vote for OOXML5, leading the Swedish Standards Institute (SIS) to declare its vote in favor of OOXML invalid. Critics have speculated that similar practices occurred in Italy, Switzerland, Spain, and other countries. Such allegations have prompted the EU to launch an investigation into Microsoft’s practices during the ISO vote.
OOXML was submitted to ISO using the fast-track process, which was intended to make it easier to approve an ISO standard if it has already been approved by an existing standards organization. This was meant to speed up the process for standards whose problems have already been resolved and where consensus has already been achieved. The process generally requires three years or more; fast-track can cut this time to six months.
The first review of the 6,000-page OOXML proposal resulted in a disapproving ballot by national bodies on September 2nd. There were over 3,500 comments. The issues identified with OOXML did not stop there.
After the 3,500 comments during the initial ballot, one delegate wrote, “I and my reviewers found 13 additional errors in the original specification. However, national bodies were not allowed to submit new comments (and rightly so, otherwise there would have been total chaos). Therefore, there was no way to submit and correct them.”6
In response, ECMA submitted a proposed Disposition of Comments report that was close to 2,300 pages long. This Disposition of Comments contained proposed changes scheduled to be discussed at a Ballot Resolution Meeting (BRM) in February. This gave only six weeks to review this documentation (that’s a rate of 55 pages per day) before the BRM; it was impossible for all technical issues to be addressed or resolved in that timeframe.
The BRM meeting itself only lasted one week, even though the JTC 1 Directives impose no such time limitation. The normal course for a BRM is to meet, recess with email discussion, and to meet again until consensus is reached on the changes to a proposal. (Remember, the JTC 1 emphasizes consensus in its standardization process.)
Complaints have been lodged with the ISO by some national bodies alleging that the BRM process was inadequate for the number of issues needing resolution. In the final vote at the BRM, only six of the thirty members voted to approve the changes. Four voted to disapprove, and 20 either abstained or refused to register and vote at all.
Obviously, ISO should have referred the proposal to a working committee for further improvements before it was placed on a fast track ballot. But the relevant ISO process was not designed to make this possible. When this is combined with the addition of new members at the last minute in order to influence a vote, the process is fatally flawed.
The IT industry clearly needs systems so that companies can work well together, and these systems need to work well in all countries. The ISO process for IT standards was designed to promote interoperability, portability, and cultural and linguistic adaptability,1 using a consensus process. We believe strongly in these goals, but the current process is not designed to achieve them. The OOXML proposal has exposed serious flaws in ISO process–especially in the fast-track process–and we believe these flaws need to be fixed.
The credibility of ISO is at stake.
March 20, 2008 09:29 PM
As we’re off for a much-deserved long weekend here in the US, we’re bringing you the Friday round-up… a day early. Not much going on this week, but a couple of things we thought we’d leave you with:
Ever see something you think we should include in our weekly round-up? Let us know. We’re always looking for the most interesting bits.
March 19, 2008 08:07 PM
Miss out on JBoss World in Orlando? Or are you still wondering how JBoss and middleware fit into the bigger picture? These and more curiousities are answered in our summary video. And if you’re wondering what the new CEO’s like, you can catch him here as well.
March 18, 2008 09:28 PM
This is a new feature that has been requested in the Red Hat Enterprise Linux product line. The supported algorithms are DES, MD5, and SHA-256/512. They will be available after the upcoming updates releases as well as in Rawhide. The new algorithms will be configurable via Kickstart only. Here is the correct code.
authconfig --enableshadow --passalgo=descrypt rootpw fedora
authconfig --enableshadow --enablemd5 rootpw fedora
or
authconfig --enableshadow --passalgo=md5 rootpw fedora
authconfig --enableshadow --passalgo=sha256 rootpw fedora
authconfig --enableshadow --passalgo=sha512 rootpw fedora
If you provide an encrypted root password in the above examples it will not be encrypted again.
March 17, 2008 09:48 PM
At the moment, JBoss Technical Support is available in English. Support for other languages may be added at a future time.
When transferring an existing Red Hat Support case in another language to JBoss Support, please be prepared to provide a description of the case in English for the JBoss engineer.
March 14, 2008 08:53 PM
Welcome to Friday, our favorite day of the week. And here’s our handful of recent news we couldn’t resist sharing, to send you on your way into the weekend:
Charles Chen has been in meetings with the Philippine Business for Social Progress (PBSP) to evaluate the XO, and comments:
“This is to inform all the members of OLPC PH that I had met two weeks ago with the officials of the Philippine Business for Social Progress (PBSP), the country’s largest NGO in working in partnership in establishing an OLPC pilot to be done with the primary school level of the Don Bosco Technical College in Mandaluyong.”
“PBSP can support OLPC PH by developing the needed governance practices we need to implement this program. At the moment, PBSP is currently evaluating the project requirements of this pilot as well as the possible use of the XO for its own educational program. Their program initially aims to provide about 20,000 laptops and will be a big boost to OLPC PH if they find XO suitable for their needs.”
March 13, 2008 08:33 PM
Whether you’re a returning guest or a just thinking about attending, the Red Hat Summit is fast approaching. Check out this year’s Summit preview video, and when you’re done, hit the event website and get the details. We’d love to see you there. And get some chowda.
March 12, 2008 08:09 PM
In the event that a process is not achieving the desired performance performance benchmarks, it can be helpful to set CPU affinity, real-time scheduling policy and real-time scheduling priority. Experimenting with different options using the taskset and chrt commands can help determine if this approach will provide the desired results.
The taskset sets CPU affinity for a process. The chrt sets real time scheduling options. The two commands can be used in tandem. For example:
taskset -c 2-3 chrt -f 1 <command>
The above usage would force <command> to run on CPUs 2 through 3, using the “fifo” scheduling policy at priority level 1. The results of using these options depend on the workload of the application, as well as the load of the system in general.
For more information on the taskset and chrt commands, see their respective man pages. For more information on setting these attributes within an application, rather than when launching the application, see man 2 sched_setaffinity and man 2 sched_setscheduler.
March 11, 2008 03:24 PM
I listened to a webcast from JBoss World today with a group of people. After hearing several speakers announce new middleware products and initiatives (as JBoss is the leading force in open source middleware), one of them turned to me and asked, “Just what is middleware?” When I started to describe transaction servers and database connection pool sharing, she held up a hand and said, “No. I want to know what it is in real world terms, and why it’s a big deal.”
That got me thinking and sent me to Google to look for a short definition of middleware. I found a lot of them, but they mostly were either too vague or too dependent on the reader already having some knowledge about middleware. Then, I found this one:
middleware: The kind of word that software industry insiders love to spew. Vague enough to mean just about any software program that functions as a link between two other programs, such as a Web server and a database program. Middleware also has a more specific meaning as a program that exists between a “network” and an “application” and carries out such tasks as authentication. But middleware functionality is often incorporated in application or network software, so precise definitions can get all messy. Avoid using at all costs…
And that really got me thinking about how to describe middleware and why it matters. What I was searching for was a real-world analogy that would make sense to people with varying levels of computer and software experience. And then, it hit me.
Middleware is plumbing.
There are four ways that this is true.
First, it’s mostly invisible.
You don’t generally see much of the plumbing in your house. What you see is the water. As a consumer, you don’t see middleware. You see the web sites and the information flow that middleware make possible. This is part of why middleware is hard to define. If you live and work with software, and if you’re reading this you probably do, then you’re very aware of software packages at the top level in a logical view, such as e-commerce web applications, and packages that exist at the bottom level, such as databases and the operating system. The middle part, that plumbing that ties everything together, can seem less concrete and identifiable.
Second, it provides a standard way of doing things.
If you wanted to build your own plumbing from scratch, you could. But it’s much easier to just buy plumbing fixtures. You, as a software developer, could design and build your own application servers, database connection drivers, authentication handlers, messaging systems, etc. But these wouldn’t be easy to build and maintain. It’s much easier to make use of middleware components that are built according to established (and especially open!) standards. In middleware, these standards take the form of libraries of functions that your programs call through well-defined application programming interfaces (APIs). You call these functions instead of having to invent your own.
Third, it ties together parts of complex systems.
In your house, you have kitchens, heating systems, bathrooms, washing machines, garden faucets, etc. Each plays an important part in making your house livable. You almost never have to worry about not having running water because the plumbing is robust and reliable. It just keeps the water moving through the pipes. Middleware keeps information moving through complex web-based applications. One of its primary tasks is to connect systems, applications, and databases together in a secure and reliable way. For example, let’s say you bought an over-priced sweater at a store web site last night. What happened? You looked through various sweaters’ images, selected color and size, entered a charge card number, and that was it, right? Well, behind the scenes, middleware made sure that the store’s inventory database showed that sweater in stock, connected to the charge card company’s database to make sure that your card wasn’t maxed out, and connected to the shipping company database to verify a delivery date. And, it made sure that hundreds or thousands of people could all shop that site at the same time. Also, while it looked to you like you were looking at one web site, middleware tied together many different computers, each in a different location, all running the store’s e-commerce application, into a cluster. Why is this important? To make sure that you can always get to the store online, even if some of these computers are down due to maintenance or power failures.
There’s another similarity about your household plumbing and middleware tying systems together. They both enable you to tie together systems that were built by different people, at different times, without your having to reconstruct everything from scratch. Think about your house for a minute. If your house is older, you probably have several generations of plumbing all working together. You didn’t have to upgrade your washing machine with multiple service packs when you installed a new hot water heater. In middleware, one the most powerful approaches is service-oriented architecture (SOA) based on an enterprise system bus (ESB). As its name implies, an ESB provides a server, messaging, and APIs that function like a hardware bus. In order to integrate enterprise software applications developed at different times, by different organizations, and even communicating via different protocols, you don’t have to rewrite them to speak one consistent language. The ESB enables you to “plug” these applications as services into the bus. The ESB takes care of transforming messages between the protocols and routing the messages to the correct services. In February, Red Hat announced the JBoss SOA Enterprise Platform. This platform provides a flexible, open source solution for businesses to integrate applications, SOA services, and business events, as well as to automate business processes.
Fourth and finally, it lets you worry about other things.
When you put an addition onto a house, what do you worry about? Bathroom fixtures, kitchen appliances, flooring, colors, and how to pay for it all. It’s a very stressful process. The last thing you want to worry about is whether you want 3/4-inch or half-inch pipe, copper or PVC connectors, #9 or #17 solder, etc. With middleware taking care of all the invisible functions, you (as a software developer or a business owner) can concentrate on building software to solve your business problems and fulfill your customers’ needs.
My father once told me, “when you move to a new town, don’t look for a doctor–first thing, you find a good plumber so you can sleep nights.” It’s like that with middleware. It may be mostly invisible, but it keeps things running so a lot of developers and managers and customers can sleep at night.
March 10, 2008 09:02 PM
In Red Hat Enterprise Linux 5, device-mapper-multipath is installed by default. This is a change from Red Hat Enterprise Linux 4. If a third party multipathing solution is in use, device-mapper-multipath should be disabled to avoid any conflict between multiple multipathing technologies. To disable device-mapper-multipath, turn it off with the following command:
chkconfig multipathd off
In addition, make sure the /etc/sysconfig/mkinitrd/multipath file has the following line:
MULTIPATH=NO
By default, /etc/multipath.conf has all devices blacklisted. If this default configuration has been changed, the change should be reverted. If the devices are not blacklisted, then running the multipath command could cause a conflict with other multipathing software. The /etc/multipath.conf file should contain the following:
# Blacklist all devices by default. Remove this to enable multipathing
# on the default devices.
blacklist {
devnode "*"
}
These steps will ensure that device-mapper-multipath does not conflict with any other multipathing solution in use.