Occasionally as a Linux administrator you will be in the situation where working on a remote server and you are left with no option but to force a reboot the system. This may be for a number of reasons, but where I have found it most frequent is when working on Linux clusters in a remote location.
When the "reboot" or "shutdown" commands are executed daemons are gracefully stopped and storage volumes unmounted.
This is usually accomplished via scripts in the /etc/init.d directory which will wait for each daemon to shut down gracefully before proceeding on to the next one. This is where a situation can develop where your Linux server fails to shutdown cleanly leaving you unable to administer the system until it is inspected locally. This is obviously not ideal so the answer is to force a reboot on the system where you can guarantee that the system will power cycle and come back up. The method will not unmount file systems nor sync delayed disk writes, so use this at your own discretion.
To force the kernel to reboot the system we will be making use of the magic SysRq key.
The magic_SysRq_key provides a means to send low level instructions directly to the kernel via the /proc virtual file system.
To enable the use of the magic SysRq option type the following at the command prompt:
echo 1 > /proc/sys/kernel/sysrq
Then to reboot the machine simply enter the following:
echo b > /proc/sysrq-trigger
Voilà! Your system will instantly reboot.
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The Recital Oracle Gateway requires the Oracle libclntsh.so shared library. If this file is unknown to ld.so.conf, add it using the ldconfig command.
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Full details on Recital Function Keys can be found in the Key Assist section of the Help menu, or in our documentation wiki here.
System Requirements:
- Minimum memory: 4MB
- Minimum Diskspace: ~20MB
In Adobe's own words:"Adobe® AIR® is a cross-operating system runtime that lets developers combine HTML, Ajax, Adobe Flash®, and Adobe Flex® technologies to deploy rich Internet applications (RIAs) on the desktop."
The outcome of this combination of technologies is that developers can design and render quite beautiful user interfaces cross platform. For us desktop Linux users it is nice to have
an additional avenue for obtaining and running attractive desktop applications.Examples of great Adobe air applications are Adobe.com for My Desktop, TweetDeck and the Times Reader. You can download these applications and many more at the Adobe Marketplace.
The easiest way to install Adobe Air on Fedora 12 is to download the latest build from Adobe, click here.
Once you have downloaded the .bin file do the following at the shell:
su - chmod +x AdobeAIRInstaller.bin ./AdobeAIRInstaller.binOnce you have Air installed, there is a slight tweak you will have to do to get it running on Fedora 12, it is related to the security certificates. This can be remedied in one simple line at the shell prompt as root.
su - for c in /etc/opt/Adobe/certificates/crypt/*.0; do aucm -n $(basename $c) -t true; doneWhat this line is doing is using the aucm which is the Adobe Unix certificate manager to set the certificates installed as trusted.
You will now be able to go to the Adobe Marketplace and download and run Air applications without any issues.
Enjoy!
After split brain has been detected, one node will always have the resource in a StandAlone connection state. The other might either also be in the StandAlone state (if both nodes detected the split brain simultaneously), or in WFConnection (if the peer tore down the connection before the other node had a chance to detect split brain).
At this point, unless you configured DRBD to automatically recover from split brain, you must manually intervene by selecting one node whose modifications will be discarded (this node is referred to as the split brain victim). This intervention is made with the following commands:
# drbdadm secondary resource
# drbdadm disconnect resource
# drbdadm -- --discard-my-data connect resource
On the other node (the split brain survivor), if its connection state is also StandAlone, you would enter:
# drbdadm connect resource
You may omit this step if the node is already in the WFConnection state; it will then reconnect automatically.
If all else fails and the machines are still in a split-brain condition then on the secondary (backup) machine issue:
drbdadm invalidate resource
On entry to the .rsp page.
IF type( _session["state"] ) != "U"m_state = _session["state"]RESTORE DATASESSION FROM m_state
ELSE
// open up your tables for the first timeENDIF
SAVE DATASESSION TO m_state_SESSION["state"] = m_state
FOREACH array_expression AS value
statements...
ENDFOR
FOREACH array_expression AS key => value
statements...
ENDFOR
The first form loops over the array given by array_expression. On each loop, the value of the current element is assigned to value and the internal array pointer is advanced by one (so on the next loop, you'll be looking at the next element). The second form does the same thing, except that the current element's key will be assigned to the variable key on each loop. This form works only on associative arrays and objects.
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