Querying AIX device attribute values with the AIX kernel debugger

We all know that you can modify online certain attributes on AIX devices, like queue_depth on disks for example :

# chdev -l hdisk15 -a queue_depth=16

However, some attributes changes need a reboot as the device property is in use at that time. You can modify the property by specifying that it will be modified at boot time, with the 'chdev -P' option. This can lead to quite some confusion : imagine a junior sysadmin changing the property, but forgetting the reboot. The 'lsattr' command will report the modified value, but not if it is effectively in use.

We can obtain the currently used value by interrogating the AIX kernel with the kernel debugger, quite a handy feature.
The following command shows the current value of cmd_num_elems on the virtual fiber adapter :

echo vfcs fcs0 | kdb | grep num_cmd_elems 

The following command lists the current values of the queue_depth parameter on hdisk15 :

# echo scsidisk hdisk3 |kdb |grep queue
    ushort queue_depth   = 0x8;


Over the years, I've fallen in love with the AIX multibos command. Here's a little procedure howto test patches without even a reboot of the system :

  • First, clear out all references to old multibos instances :
  • # multibos -R
  • mount the patch server directory with the patch bundle :
  • # mount nim:/patches /mnt
  • Create a multibos instance of the running kernel and update it :
  • # multibos -Xs
    # multibos -Xac -l /mnt/6100-07-07
  • Check the Standby BOS and review any problems :
  • # multibos -S
    	MULTIBOS> oslevel -s
  • WARNING : adding multibos, will change bootlist, if not wanted, use -t flag :
  • # bootlist -m normal -o
    hdisk0 blv=bos_hd5 pathid=0
    hdisk0 blv=bos_hd5 pathid=1
    hdisk0 blv=hd5 pathid=0
    hdisk0 blv=hd5 pathid=1


You're one in a million
that's what you are
to us so very special
like a bright shining star !

On March 24th, we got blessed with a baby daughter Luna, 3.4kg and 52 cm large (small).

The Hobbit : an unexpected journey

After the Lord of the Rings trilogy, we have all eagerly been awaiting to venture back to Middle-Earth. Most of the Tolkien fans danced of joy when Peter Jackson announced that the prequel The Hobbit would be poured into 3 movies also. Finally, I had a chance now to see the first part of The Hobbit, called 'An Unexpected Journey'. And it's brilliant.

A lot of criticism mentioned the slow pace of the movie, but that did not bothered me once. What a beautiful role for Radagast, the odd hermit wizard which hardly got any attention in the Tolkien books. The attention to the Tolkien world has again been so intense, that after the movie I dove into the books to check on some details (who were the two blue Istari which Gandalf says he forgot the names of ? Has Radagast really been into Dol Guldur ? And so on). And Martin Freeman is just brilliant as the young Bilbo, wandering around in the magnificent scenery of New-Zealand.

Are there no bad points to give out ? Sure, some of the digital hocus-pocus really disappointed, such as the character of Azog, which always remains rubbery and never comes to life. Also, the goblin cave is just a digital splatterfest, and just feels too crammed and noisy onto the screen. The humor that was so prevalent in the book has been cut down drastically so the movie feels a bit too much of Wagnerian proportions. There has also been taken way more freedom into diverging away from the book : Radagast has never been into Dol Guldur and Galadriel was never mentioned in 'The Hobbit'.
But that's nitpicking.

Drupal 7

It has been a very long & bumpy road, but I have finally managed to upgrade this site to Drupal 7. Just in time, as Drupal 8 is getting finished and polished. There is still stuff that needs to be converted, most noticeable are the taxonomy_browser and taxonomy_image functionalities, that will be fixed in the next couple of weeks.

If you see anything abnormal, just leave a note in the reply section !

John Wed, 02/27/2013 - 10:15

Congrats with your Drupal 7 install !

Dirk Fri, 03/01/2013 - 11:00

The upgrade to Drupal 8 promises to be even harder. Just warning you ;)