I had a very nasty experience with Oracle ASM recently. A long story short, ASM crashed on both our RAC nodes when removing a corrupted archive file on file and incarnation number (removing it on it’s name didn’t work). Starting the instance failed. When removing the failing diskgroup ASM was happy again. Luckily the failing diskgroup only housed archivelog files, except for one database it also held it’s index datafile. So that one wouldn’t come up. If you’re in such a situation, you can use the Oracle tools amdu in combination with kfed to extract the missing datafile or archivelogs (in our situation) from a dismounted diskgroup. If I knew that from the start it saved me alot of frustrating hours.
Oracle ASM lifesaver
June 29, 2012 by · Leave a Comment
Unattended icaclient installation
June 13, 2012 by · Leave a Comment
For a new project we need to build Linux workstations with Debian. One of the wishes is to have a Citrix Receiver installed, so we created a nice install script, but the EULA agreement is not very helpful in an unattended install.
echo "icaclient icaclient/accepteula boolean true" | debconf-set-selections dpkg -i /tmp/icaclient_12.0.0_amd64.deb
This was found by doing the following:
cd /tmp dpkg-deb -x icaclient_12.0.0_amd64.deb extract/ dpkg-deb -e icaclient_12.0.0_amd64.deb extract/DEBIAN
Have a look at the contents of the extract/DEBIAN/config file and you’ll find out.
It took me quite some time to figure this one out, so I thought let’s share.
Intermittent WiFi signal
June 7, 2012 by · Leave a Comment
I experienced a intermittent WiFi signal lately on multiple devices. Since I haven’t touched my router configuration for a while it had to be something different. Some time passed before I realized it could be a neighbor who was using the same frequency I was using. Looking into my router configuration it turned out I was using a fixed frequency (2462). Below are the frequencies that can be configured.
Channel 1 : 2412 Mhz 11g Channel 2 : 2417 Mhz 11g Channel 3 : 2422 Mhz 11g Channel 4 : 2427 Mhz 11g Channel 5 : 2432 Mhz 11g Channel 6 : 2437* Mhz 11g Channel 7 : 2442 Mhz 11g Channel 8 : 2447 Mhz 11g Channel 9 : 2452 Mhz 11g Channel 10 : 2457 Mhz 11g Channel 11 : 2462 Mhz 11g Channel 12 : 2467 Mhz 11g Channel 13 : 2472 Mhz 11g
While thinking about which new frequency to choose I figured out there is an option to choose the least congested. That’s what I need in an area where there are at least 30+ different access-points.
router#conf t Enter configuration commands, one per line. End with CNTL/Z. router(config)#interface Dot11Radio0 router(config-if)#channel 2457 router(config-if)# channel ? <1-2472> One of: 1 2 3 4 5 6 7 8 9 10 11 12 13 2412 2417 2422 2427 2432 2437 2442 2447 2452 2457 2462 2467 2472 least-congested Scan for best frequency router(config-if)# channel least-congested router(config-if)#end
Now every WiFi enabled device in the house is happy again.
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