Month: April 2012

scsi_id and UDEV issues (update)…

Last month I wrote about a problem I saw with scsi_id and UDEV in  OL5.8. As it screwed up all my UDEV rules is was a pretty important issue for me. It turned out this was due to a mainline security fix (CVE-2011-4127) affecting the latest kernels of both RHEL/OL5 and RHEL/OL6. The comments on the previous post show a couple of workarounds.

Over the weekend I started to update a couple of articles that mentioned UDEV rules (here and here) and noticed the problem had dissapeared. I updated two VMs (OL5.8 and OL6.2) with the latest changes, including the UEK updates and ran the tests again and here’s what I got.

# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 5.8 (Tikanga)
# uname -r
2.6.39-100.6.1.el5uek
# scsi_id -g -u -s /block/sda/sda1
SATA_VBOX_HARDDISK_VB535d493d-7a44eb0f_
#

# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.2 (Santiago)
# uname -r
2.6.39-100.6.1.el6uek.x86_64
# /sbin/scsi_id -g -u /dev/sda1
1ATA_VBOX_HARDDISK_VB2b5dc561-4ae6e154
#

So it looked like normal service had been resumed. 🙂 Unfortunately, the MOS Note 1438604.1 associated with this issue is still not public, so I couldn’t tell if this was a unilateral change in UEK, or part of a mainline fix for the previous change.

To check I fired up a CentOS 6.2 VM with the latest kernel updates and switched an Oracle Linux VM to the latest RHEL compatible kernel and did the test on both. As you can see, they both still don’t report the scsi_id for partitions.

# cat /etc/redhat-release
CentOS release 6.2 (Final)
# uname -r
2.6.32-220.13.1.el6.x86_64
# /sbin/scsi_id -g -u /dev/sda1
#

# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.2 (Santiago)
# uname -r
2.6.32-220.13.1.el6.x86_64
# /sbin/scsi_id -g -u /dev/sda1
#

It could be the associated fix has not worked through the mainline to RHEL and CentOS yet. I’ll do a bit of digging around to see what is going on here.

Cheers

Tim…

Update: It appears the reversion of this functionality may not be permanent, so I’ve updated my articles to use a “safer” method of referencing the parent (disk) device, rather than the partition device.

Avengers Assemble…

If you have ever enjoyed a superhero film in your life you simply must go to see Avengers Assemble. It is totally fantastic. It has great action scenes, some really neat characters and is really funny at times too. I’ve not enjoyed an action film this much since I saw the first Iron Man Film. Awesome!!!

Iron Man/Tony Stark : I want to be him. He is too cool for school. He is Kool and the Gang.

The Hulk : All The Hulk films have been a bit of a let down because the only thing I really like is the green monster running around destroying things. The great thing about this film is it doesn’t have to fill two hours with the story of Bruce Banner, so you just get to see the bit you really want to see. The Hulk is fantastic in this film and adds greatly to the comedy elements. He literally had the whole audience laughing hard on several occasions.

Thor : I know the Thor film got a bit of a slating, but I liked it. I think the Thor character works well in this film.

Loki : I think he worked well as the bad guy. It’s always good when the bad guy is a little fragile.

Captain America : I didn’t like the CA film and I don’t really like the character in this film. It’s not Chris Evans fault. I just think the character is a bit lame and I feel no connection with him. He’s just totally meh.

Black Widow and Hawkeye : Whatever… Never heard of them before this film. Have no feeling either way about their presence in the film.

I guess you can see that in my head it’s an Iron Man and Hulk roadshow and I loved it.

So now I’ve raised your expectations you are going to hate it. 🙂

Cheers

Tim…

Linux Firewall and SELinux (RHCSA)…

I’ve put the last two articles in the RHSCA certification series live.

These took a little bit of time because I was in denial (and ill for a couple of weeks). When I put the previous batch of articles live, I mentioned these objectives were the ones I knew least about. That’s mostly because my standard operating procedure for Oracle servers is to disable SELinux and turn off the firewall. I reached out to the OakTable to see what Oracle do on their engineered solutions (Exadata and ODA) and it seems the answer depends on which part of the solution you are discussing (RAC nodes or storage cells) and the age/patch level of the kit software you have.

In the early releases it was very much SELinux and firewall disabled. Later release have SELinux in permissive mode on some components and the firewall enabled on some components.

Running SELinux in permissive mode seems a bit pointless to me, unless you are investigating what policies need to be changed in order to switch to enforcing it at a later date. I’m still not convinced about the relevance of SELinux for a database server at this point, but my opinion may change as I get more familiar with it. It is quite literally an uneducated opinion at this point. 🙂

Now I’ve completed the revision notes for the RHCSA exam I guess I should think about taking the exam. I’ve just checked the Red Hat website and the earliest I could sit the exam in Birmingham is July. Unfortunately I’m out of the country for much of July, so it would appear the middle of August is probably going to be the first real opportunity. Most other cities have a couple of dates a month, but not here. Once again Birmingham proves itself to be at the arse-end of British I.T. 🙁

Cheers

Tim…

You don’t need an app for that… (browser stats)…

I’m getting a bit sick of reading about how not having a mobile presence is a big fail. Once again the marketing people take a one-size-fits-all approach and assume that if you are on the net, then people must want to use your services from mobile devices. This is utter nonsense. In reality, the need for a mobile presence depends very much on what services you are offering and who you are offering them to.

For example, look at the OS breakdown for my website over the last month.

So 98.6% of visitors are using non-mobile devices. This is not a surprise since my website focuses on Oracle DBAs and developers, who are unlikely to be working from mobile devices. Would you suggest a real company with this focus and these sort of web stats should invest in a mobile presence?

Just out of interest I checked the browser stats.

Since I last checked in November, Chrome has bitten even more market share from IE and Firefox. We’re fast approaching a 3-way tie. Looks like Microsoft really do need all those IE adverts after all. 🙂

Cheers

Tim…

Lockout…

If you took Escape from New York and gave it a Sci-Fi touch-up you would probably end up with Lockdown. That’s not a bad thing, since I really enjoyed EfNY when I saw it as a kid. I thought Lockdown was a fun action film. It doesn’t push the boundaries, but what it does, it does pretty well.

Guy Pierce‘s character (Snow) is actually pretty similar to Kurt Russell‘s character (Snake Plissken). Mouthy and cool. Nice also to see Joseph Gilgun from the This is England film and TV spin-offs.

Overall I would say lightweight, but quite enjoyable.

I’ve been playing catch-up this week. Of the four films I’ve seen I think I enjoyed this one the most.

Cheers

Tim…

Fasthosts : Good Riddance…

It’s been a couple of weeks since I stopped hosting my website with Fasthosts. It’s too early to start singing the praises of the new hosting company, but so far so good.

As a parting shot, when I asked Fasthosts to cancel my hosting account I asked for a refund on the 8 months of outstanding service I had paid for. I got the answer back today and it was a definite no.

I’m not particularly surprised at this, but I thought as a good will gesture to a customer of 11 years they may do the decent thing and give me my money back. It’s not like I wanted to leave. I was forced to by their complete incompetence.

My advice to anyone considering using Fasthosts would be DONT!

Cheers

Tim…

Repairman Jack : Gateways…

Gateways is the seventh book in the Repairman Jack series by F. Paul Wilson.

Jack’s dad has an “accident” and is left in a coma. Jack goes to visit him and tries to find out what happened. Another brush with “The Otherness” inevitably follows.

As I’ve come to expect, the backdrop to the story is quite sinister, but it moves too fast for you to dwell on that. It’s more like a full on action story and much less bleak than some of the previous stories. Maybe I’m just getting acclimatized… 🙂

Cheers

Tim…

PS. Having this cold has certainly allowed me to motor through some of these books.

Wrath of the Titans…

Wrath of the Titans has one clear advantage over the previous film. It’s not a remake of a film I have seen masses of times. That alone makes it a little more interesting for me.

It looks great, but it does seem to drag on at times. I came out thinking they should have cut about 30 minutes to make it flow better. Imagine my surprise when I found out the running time was only 99 minutes. 🙂

IMHO this is a “wait for DVD” film. Even then I would hold on until you can get it in a sale. It’s not bad, but it won’t rock your world.

Cheers

Tim…