Long Time Coming

Ok.. So it has been a while since I have entered a post. It does not mean that I have not been doing anything. Quite the contrary. Now that I have had a chance to breathe I will begin entering some posts that will hopefully be of interest. They will probably be more on the lines of VMware ESX 4 and ESXi 4 since that is what I have been working with as of late. Without any further waste of time, here is the first post:

Setting up your own iSCSI...

The average person is probably thinking "What is iSCSI and why would I care" but the VMware folks in our midst are saying "Tell me more...". I needed to set up a VMware ESX environment at home to test ESXi 4 and some other VMware products. Working on a budget, I sourced a used Dell PE2850 and downloaded the free ESXi from VMware. Now back to the budget. I managed to get the server with 2 - 18GB disks but I did not have much in the way of money left for additional space. So out with the iSCSI solution. Since ESXi will connect to iSCSI over a normal Ethernet network I could add an larger SATA drive to a normal PC and then present it via the iSCSI software to the ESXi host and BANG.. more ESXi storage.

Can I speak with root?

Once again... this is not a very exciting post. Unless you are having to re-install a Linux system because you do not have the root password, then it could be like sex. Maybe just a piece of candy but you get the idea.

First get the installation media for said system. In this example it is a Red Hat 4.6 or 5.1 system. Then perform the following:
1. Boot from the media. When it comes up with the installation prompt type "linux rescue"
2. The system will continue to boot and ask about the network interface - it is not needed
3. When it asks about mounting the installation allow it to mount with read-write

Now for the fun part.. ok as fun as it gets

4. The hard drive installation will be under /mnt/sysimage
5. Change to /mnt/sysimage/etc and then edit shadow with vi
6. Find the root entry in the shadow file it will look like:

root:Ep6mckrOLChF.:10063:0:99999:7:::

7. Change the line in the file to look like the following:

root::10063:0:99999:7:::

8. Save and exit vi, and then reboot the system
9. Voila, no root password.
10. Log in as root and set the password with the passwd command ASAP!

What to expect....

Ok when it comes to programming ANYTHING I am pretty slow. I needed to change the firewall ruleset on quite a few ESX servers and it seemed like a script was in order to make this change for me. However, since I could not get the Opsware client to run a script remotely (that was part of the problem) i needed to figure out an alternative method.

Enter EXPECT.. I had heard it mentioned before but not really understood what it did. Basically you can open a connection to another system and if you can tell the script what to "expect" then it will know what to send it in return.. pretty cool huh.. This is the part where my wife's eyes glaze over.

Basically what I was doing is this...

spawn ssh some_user@somemachine.com
expect "someuse@somemachine's password:"
send password\r
expect "someuser@somesmachine"

And so on.. you get the idea. BUT.. is there not always a but... the issue I was having was that the prompt was on a VMware ESX server and looked like [usename@hostname username]$. I entered the text verbatim so that the expect showed the brackets etc. It puked. But by removing the brackets and only going to the end of the first word it works. Example..
expect "someuser@hostname" works but expect "[usename@hostname username]$" does not. Go figure. So I am going to stop while I am ahead today and revel in my glory....

Just rember... You Stay Classy San Diego.

Backup a minute..

Ok.. another yawner of a post but hey that is me. I am working on process of backing up the VM's in an environment and making it as quick to recover as possible. In my search I ran across a product called esXpress v3.1. It is pretty cool (ok as cool as VM software can be). It does a couple things:

1. It will put a VM into "Snapshot Mode" and then perform a backup of the VMDK.
2. It can put the VMDK backup to SMB/FTP or SSH.
3. After it is done it will remove the snapshot.

THIS IS DONE WHILE THE VM IS RUNNING! HOW COOL IS THAT!

Oh and I did not mention the best part. The software is FREE! Now there are additonal features such as being able to make backups local and remote at the same time, having additional helper machines, encryption and other things.

Check it out at www.esxpress.com

My Friend CRON...

OK another dry post but hey.. this is not the Life and Times of Someone Exciting.. sorry. I was at work minding my own business when I realized that my little automated email was not there waiting in my inbox from several servers on Mondays when I came in. (Maybe it had a "Case of the Mundays" as described in the movie Office Space) Computers are like Marines. They are not supposed to choose what orders they follow and what ones they do not. I began to investigate.


Looking into the cron log (/var/log/cron) I noticed that NONE of the CRON jobs were running. I am on to something. I looked into the messages log and sure enough there was an entry "Authentication token is not longer valid; new one required". Clear as mud, of course. So I went to the worlds User Manual.. Google. It showed that there was an issue with the root user id. Huh? I just used it. Logging into the console with the root user id, I was greeted with a message that the id was aged out and would have to be changed! I DID NOT GET THIS WHEN I SU to the ROOT ACCOUNT! I changed the password and restarted the crond service. All good now..

As usual, I hope someone benefits from my stupidity.

Don't Go Away Mad...

Ok, it has been a little while since the last post, but hey, I don't create magic that often (never if you ask my wife).

One of the things we were dealing with is an automated flow that deleted our Virtual Machines. This is a good thing if you want the VM's gone but in our case we kind of wanted them there but they kept getting deleted. Needless to say this was NOT a good thing. I was able to come up with a solution. We modified the delete script to a rename script.

Here is how it works....

The script was using "rm vm_name" and with a little trial and error I came up with...



mv vm_name vm_name.`date +"%Y%m%d"`_`date +"%H%m"`

Now that seems complex but it moves (hence the mv command" from the vm_name directory to vm_name.yearmonthday_hourminute .. for example a VM named vm01 decomissioned on December 19th at 11:15 am would be...

vm01.20081219_1115

Now it it would still be resident on the disk but it would show when it was decomissioned. This will help if you want to keep VM's around for 30 days or so before deleting them.

Also some other steps were not covered.. the vmware-cmd was used for all the shutdown and unregistering of the VM's..

Hope this helps somone..

Perl and the Array..

Ok this is not going to be much fun for the average person but I found it helpful. Figured I would put it out here for everyone to ponder.. much like the meaning of life, why are we here, how my belly button fills with lint. The REALLY important stuff.

I was working on a small script ( I really do not call it a program). In this script, I needed to find the most recent log file on a Linux box and do something with it. How I accomplished this was a rather cumbersome Perl script but here goes:

1. I was able to sort the data by using "ls -c". This put the newest log file on top.
2. The I was able to pipe that data into an array. If you are not familiar with an array, it stores information in separate entries kind of like of a database.
3. Since I wanted the first entry in the array I was able to pull it using the following code:

@item_wanted = $array_i_am_using[0];

Then I can print the array item out if needed etc.

Hope this helps someone.

I might be reading this later in the future :)