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OPS245 Lab 5

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{{Admon/caution|DO NOT USE THIS VERSION OF THE COURSE. This page will no longer be updated.|'''Debian version here:''' https://seneca-ictoer.github.io/OPS245

'''CentOS version here:''' https://seneca-ictoer.github.io/OPS245-C7 '''Andrew's version here:''' http://wiki.littlesvr.ca/wiki/OPS245_Lab_5}}

=LAB PREPARATION=

{| width="40%" align="right" cellpadding="10"

#Perform this section in your '''c7host''' machine

~~#Use <code>sudo -i</code> to get temporary '''root''' permissions.~~#Change to ~~the~~ your '''~~/root/~~bin''' directory.#Download the following shell script by issuing the following command: <code>wget https://~~ict~~raw.~~senecacollege~~githubusercontent.cacom/~~~ops235~~OPS245/labs/main/monitor-disk-space.~~bash~~py</code>#Try to understand what this ~~Bash Shell~~ script does (refer to man pages for the '''awk''' command), and then run the script ~~as root~~with elevated permissions.

#Give execute permissions and run this shell script. This script is supposed to notify the root user by email if there are any potential partition size issues.

#Issue the follow command: <code>sudo mail-u root</code> (if you get an error, install email by issuing the command: <code>yum install mailx</code> Check to see if there are any mail messages. If there are mail messages, they do not relate to this ~~shell~~ script execution. Remove all mail messages by typing d immediately followed by a mail message number range (eg. to remove all messages. For example, if there are 5 messages, type '''d1-5''' and then press '''ENTER''' and enter '''q''' to exit the mail application).#Edit the '''monitor-disk-space.~~bash~~py''' ~~shell~~ script, and set the <code>ALERT=90</code> value to <code>ALERT=10</code>. Then save your editing session, and re-run this ~~shell~~ script.

#Run the '''mail''' command. Do you have a mail message? Enter the mail message number to view the message. If there is a message, what is the purpose of this message?

# Exit from the mail command.

<li value="11">Quickly view the tutorial about the [http://code.tutsplus.com/tutorials/scheduling-tasks-with-cron-jobs--net-8800 Using crontab] file to understand the purpose of this

file and how to basically set up a schedule to run a shell script.</li>

<li>Issue the following command to setup a crontab entry for root: <code>crontab -e</code></li><li>Enter the following line in order to run at 6:00 on the first day of every month: <code>0 6 1 * * /~~root~~home/<YOURUSERNAME>/bin/monitor-disk-space.~~bash~~ py #Runs first day of each month (6:00 am)</code> Note: Make sure you put your own username in that entry.</li><li>'''Save''' the crontab entry.</li><li>Confirm that the entry was properly saved by issuing the following command: <code>crontab -l</code></li></ol>

=INVESTIGATION 2: MANAGING HARD DISK SPACE USING LVM=

{{Admon/caution|DO NOT USE THIS VERSION OF THE COURSE. This page will no longer be updated.|'''Debian version here:''' https://seneca-ictoer.github.io/OPS245

'''CentOS version here:''' https://seneca-ictoer.github.io/OPS245-C7}}

An application called '''LVM''' is a very useful tool for Linux system administrators to easily manage file systems, in some cases, even when the computer system is running!

#Now issue the commands <code>n</code> (new partition), <code>p</code> (primary partition), <code>3</code> (i.e. next available partition number). When prompted for initial block, press '''enter''' to accept the default beginning block, and type: <code>+3G</code> at ending block (create a 3GB partition) and press '''enter'''.

#At the fdisk prompt, issue the command <code>p</code> to review the partition information.

#Enter the command <code>w</code> to save partition table and exit (~~ignore~~ read the WARNING message).

{{Admon/important|You MUST reboot your centos2 VM|You MUST now reboot your centos2 VM before proceeding!}}

<ol><li value="13">You '''must''' '''restart''' your centos2 VM to allow changes to take effect.</li>

<li>Verify that you created this partition by issuing the following command: <code>sudo fdisk -l /dev/vda</code></li>

<li>Re-issue the '''ssmlist''' command. Do you see a new /dev/vda3 partition under Physical Volumes?</li>

<li>To add the newly created partition, you need to add it into LVM to be used. Issue the following command to add the partition into LVM: <code>sudo pvcreate /dev/vda3</code> (or ''pvcreate /dev/sda3'' ) (enter '''y''' to proceed - ignore warning)</li>

</ol>

{{Admon/important|Check your VG name|Run vgs to determine your Volume Group name. If it is just centos or cl, replace centos_centos2 with centos or cl for the rest of the following commands in this lab. Do '''NOT''' try to rename your volume group.}}

<ol>

<li value="17">Issue the following command to add your new-created and formatted partition called /dev/vda3 to your volume group: <code>sudo vgextend centos_centos2 /dev/vda3</code></li>

|- valign="top"

|

[[Image:Add_virtual_disk.png|thumb|right|400px|You can add virtual hard disks for a VM by changing to the Details section for the VM (as opposed to console), click Add Hardware, fill information in the Add New Virtual Hardware dialog box and clicking Finish.'''Notice that I have my original storage in the background so I know what type of disk to select for this second device. They should match.''']]

|}

# Remain in your '''centos2''' VM for this section.

# Run the following commands and make note of the output of the commands: <code>sudo ls /dev/vd*</code>, <code>sudo ssm list</code>, and <code>sudo df -h</code>

<ol>

<li value="3">Record the size of the volume group and the amount of free space</li>

<li>At the bottom left-hand corner, click '''Add Hardware''' and add a new storage device of '''2GBs''', make sure the '''Bus type''' is selected '''using the same type as your first drive that's already there'''. If your first drive is SATA, IDE, or VirtIO, select that.</li>

<li>Click the '''VM''' menu again, and return to the '''console''' view to access your centos2 VM display.</li>

<li>Issue the command: <code>sudo ls /dev/vd*</code>, what has changed?</li>

<li>Use '''fdisk''' (''refer to how to use in Part 1'') to create a new single '''primary''' partition for '''/dev/vdb''' that fills the ''entire'' disk, save partition table (accepting default prompts would work and '''type w to write your changes'''!), restart your '''centos2''' VM.

<li> Format your new ''vdb1'' partition with file type: '''ext4'''</li>

<li>Now we'll make the new device a '''physical volume''', add it to the '''volume group''' by issuing the following commands: <code>sudo pvcreate /dev/vdb1</code> (enter '''y''' to proceed - ignore warning) <code>sudo vgextend centos_centos2 /dev/vdb1</code> '''NOTE:''' If you experience an error message, issue the '''sudo ssm list''' command, and check the '''volume group name''' under the '''"pool"''' section. If the volume group name is different than '''centos_centos2''', then use that volume group name for all remaining commands that use "centos_centos2" </li> <li>Re-issue the '''sudo ssm list''' command to see if there is any change.</li> <li>Issue the following command to extend the logical volume for the home file-system: <code>sudo lvextend -r centos_centos2/home --size +2G</code></li>

<li>Record the size of the volume group and the amount of free space. What has changed and what caused those changes?</li>

<li>Issue the '''sudo ssm list''' command. Note that your home file-system is now 2GB bigger, and you have not even rebooted your machine since you used fdisk to create a partition!</li>

<li>'''Reboot''' your centos2 VM</li>

<li>Record the LVM Management commands in your lab log-book.</li>

# Perform this part in your '''centos2''' VM.

# Issue the following command to create a mount-point (directory to connect /dev/dva3 partition to): <code>sudo mkdir /archive</code># Issue the following command to mount the partition: <code>sudo mount -t ext4 /dev/centos_centos2/archive /archive</code>

# Use the '''ls''' command to view the contents of the /archive directory. What do you see?

# Issue the '''mount''' command (without arguments) to confirm it has been mounted.

# Unmount the '''/archive''' directory by issuing the following commmand: <code>sudo umount /archive</code># Issue the '''mount''' command (without arguments) to confirm it has been ~~mounted~~unmounted.

<ol><li value="8">View the contents of the file-system table '''/etc/fstab''' by issuing the following command: <code>cat /etc/fstab</code></li>

<li>~~Issue the following command~~ use <code>sudo vi /etc/fstab</code> to add an entry to automatically mount the /archive directory upon bootup: <code>~~sudo echo "~~/dev/centos_centos2/archive /archive ext4 defaults 1 2~~" >> /etc/fstab~~</code>::Note: do not alter any of the lines that are already in that file.</li><li>~~'''Reboot''' your centos2 VM so see if~~ Issue the ~~/archive directory is automatically mounted.~~command <brb><brcode>~~'''Note~~sudo mount -a~~''' to~~ <u/span></code>~~automatically~~</ub> ~~mount~~ to see if the ~~file-systems contained~~ entry in ~~the~~ '''/etc/fstab''' ~~file without booting the VM (good for testing~~ works correctly. If there are any errors you must correct them before ~~trying a reboot)~~rebooting your machine.<br/li><brli>Reboot the machine and make sure the '''/archive''' directory is automatically mounted when the machine boots.</li>

</ol>

=INVESTIGATION 3: Scripting=

~~Under construction.~~The script used to monitor disk space earlier in the lab is very useful but has a noticeable flaw: You have to manually change the script to modify the percentage of disk space usage that will trigger a warning. It also will only ever send the email to root (unless you manually change the script).

<ol>

<li>Make a copy of of "monitor-disk-space.py" called '''disk-monitor.py''' and place it in your user's bin directory.</li>

<li>Keep the original preamble comments in the script, but add a line indicating that you modified it (and when you did so). Make sure you indicate the change in script name too.</li>

<li>Modify the script so that it will use '''argparse''' to accept command line input from the user for their preferred values for who to send the email to, and what percentage of use is worth sending an email over.

::You may choose the letters for each of these options, just document your choice in the comments in the script.

::Make sure your script keeps the original values as defaults, in case the user doesn't specify one of them (i.e. if they don't use the option to set who to send the email to, just continue to use root).</li>

<li>Test your script with both good and bad data to make sure it works.</li>

<li>When you are confident your script works, you are ready to submit the lab.</li>

</ol>

= LAB 5 SIGN-OFF (SHOW INSTRUCTOR) =

# Make certain that your '''c7host''' and '''centos2''' VMs are running.

# Switch to your '''c7host''' machine.

# Open a shell terminal, ~~'''su -''' into root, and~~ change to ~~the~~ your user's '''~~/root/~~bin''' directory.~~, open a shell terminal~~# Issue the Linux command: <code>wget https://~~ict~~raw.~~senecacollege~~githubusercontent.com/OPS245/labs/main//lab5-check.cabash</code>

# Give the '''lab5-check.bash''' file execute permissions (for the file owner).

# Run the shell script (with elevated permissions) and if there are any warnings, make fixes and re-run shell script until you receive "congratulations" message.#Arrange proof of the following on the screen: <blockquote>✓ '''centos2''' VM:<blockquote><ul><li>Output from '''sudo ssm list''' command.</li><li>Proof that '''/archive''' has been mounted</li></ul></blockquote>✓ '''c7host''' Machine:<blockquote><ul><li>Proof of creation of the shell script: '''monitor-disk-space.~~bash~~py'''</li><li>Crontab entry for '''root''' account</li><li>Run the '''lab5-check.bash''' script in front of your instructor (must have all <code> OK </code> messages)</li></ul></blockquote>✓ '''Lab5''' log-book filled out.#Upload a screen of the proof from the previous step, along with the file generated by '''lab5-check.bash''', your log book, and your disk-monitior.py script to blackboard.

= Practice For Quizzes, Tests, Midterm & Final Exam =

Andrew

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OPS245 Lab 5

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