OPS235 Lab 3 - Fedora17

This is a draft only!
It is still under construction and content may change. Do not rely on this information.

OPS235 Lab 3: Logical Volume Management and Software Package Management

Introduction

• In this lab, you are going to learn how to properly adjust your various Linux file system sizes by using and managing LVM both graphically (fedora1, fedora2) as well as command line (fedora3)

• Also in this lab, you will learn how to add and remove software packages on your different Linux systems.

Objectives

1. Learn about LVM concepts including Physical / Logical Volumes and Volume Groups.
2. Learn how to properly resize file-systems using LVM, and understand the consequences to the filesystem due to mistakes.
3. Learn how to add and remove software packages using RPM.

Required Materials (Bring to All Labs)

• Fedora 16 LIVE CD - You can burn this onto a CD-R in the Open Lab
• Fedora 16 x_64 Installation DVD - You can burn this onto a DVD-R in the Open Lab (or burn image onto a DVD+R if you are using the Freedom Toaster).
• SATA Hard Disk (in removable disk tray)
• USB Memory Stick (minimum 64M)
• Lab Logbook (Lab3 Reference Sheet) (to make notes and observations).

Prerequisites

• Completion and Instructor "Sign-off" of Lab 2: OPS235 Lab 2

Linux Command Online Reference

Each Link below displays online manpages for each command (via http://linuxmanpages.com):

LVM Information Utilities:	LVM Management Utilities:	Additional Utilities:
vgs lvs pvs vgdisplay lvdisplay pvdisplay	system-config-lvm (Tutorial) lvextend resize2fs lvcreate lvreduce pvcreate vgextend	mkfs umount yum rpm

Resources on the web

Additional links to tutorials and HOWTOs: Please read this page to get an overview of LVM:

• Logical Volume Management (Note: It is recommended to return to this guide as a reference when performing the next several investigations)
• Package Management
• User / Group Management

Logical Volume Management

Check Current LVM Information

Check LVM Information for all Fedora 16 Installs

LVM (Logical Volume Management) is used to manage hard disk drives / partitions for Unix/Linux systems. LVM provides more flexibility than just working with hard disks / hard disk partitions. Volume Groups are areas used to define Physical Volumes (i.e. hard disks, disk partitions, or other forms of storage devices). Logical Volumes are then used to represent specific portions of a file-system (directories) for that physical volume, or for a "range" or "span" of physical volumes.

Thus, LVM allows more flexibility and growth potential for Linux systems - for example, having Logical volumes span multiple hard disks. Fedora uses LVM by default upon installation. Other Linux distributions may provide the capacity to install LVM, or later install and then use Logical Volume Management.

Although the concept of LVM is simple, it takes practice and preparation (or "thinking ahead") in order to correctly use this valuable tool. It is important for students to gain an understanding of LVM, and how to manage their file-systems using LVM. It is recommended for students to read the following resource prior to this lab and/or return to the following resource while performing this lab: Logical Volume Management

At this point, having completed Lab 2 you should have roughly the following disk storage setup:
(Note: These results are output from the vgs, lvs, and pvs commands that provide volume group, physical volume and logical volume information for each of the virtual machines that you created in lab2. Before proceeding, check these values with your own system to see if you are generally "on the right track".

• fedora1

 VG         #PV #LV #SN Attr   VSize VFree
 vg_fedora1   1   2   0 wz--n- 9.50g    0

 PV         VG         Fmt  Attr PSize PFree
 /dev/vda3  vg_fedora1 lvm2 a--  9.50g    0

 LV      VG         Attr   LSize Origin Snap%  Move Log Copy%  Convert
 lv_root vg_fedora1 -wi-ao 8.03g                                     
 lv_swap vg_fedora1 -wi-ao 1.47g 

• fedora2

     VG         #PV #LV #SN Attr   VSize  VFree
 vg_fedora2   1   2   0 wz--n- 14.50g    0

 PV         VG         Fmt  Attr PSize  PFree
 /dev/vda3  vg_fedora2 lvm2 a--  14.50g    0

 LV      VG         Attr   LSize  Origin Snap%  Move Log Copy%  Convert
 lv_root vg_fedora2 -wi-ao 13.03g                                     
 lv_swap vg_fedora2 -wi-ao  1.47g                                     

 PV         VG         Fmt  Attr PSize PFree
 /dev/vda2  vg_fedora2 lvm2 a-   14.80G 4.07G

• fedora3 (Note: This VM has no GUI installed)

 VG         #PV #LV #SN Attr   VSize VFree
 vg_fedora3   1   3   0 wz--n- 9.51g    0

 PV         VG         Fmt  Attr PSize PFree
 /dev/vda3  vg_fedora3 lvm2 a--  9.51g    0

 LV      VG         Attr   LSize   Origin Snap%  Move Log Copy%  Convert
 lv_home vg_fedora3 -wi-ao   1.00g                                     
 lv_root vg_fedora3 -wi-ao   8.00g                                     
 lv_swap vg_fedora3 -wi-ao 520.00m                                     

 PV         VG         Fmt  Attr PSize PFree
 /dev/vda2  vg_fedora3 lvm2 a-   9.80G 3.83G

• f16host (i.e. "disk pack")

 VG         #PV #LV #SN Attr   VSize   VFree
 vg_f16host   1   3   0 wz--n- 232.38g    0

 PV         VG         Fmt  Attr PSize   PFree
 /dev/sda3  vg_f16host lvm2 a--  232.38g    0

 LV      VG         Attr   LSize   Origin Snap%  Move Log Copy%  Convert
 lv_home vg_f16host -wi-ao 176.62g                                     
 lv_root vg_f16host -wi-ao  50.00g                                     
 lv_swap vg_f16host -wi-ao   5.75g

Recovering VMs
Most of these investigations will take place in you virtual machines. If you make a significant mistake, your virtual machine may not boot. Remember that you created backups of your virtual machines in Lab 3, and you can restore them if something goes wrong.

Redistributing Size Among Logical Volumes

Adjusting Sizes of lv_root and lv_home

If you refer to the LV sizes of f16host, you may notice that the size of lv_root (your root system) is quite small compared to the size of lv_home. Since virtual machines that you have created are stored in the directory pathname /var/lib/libvirt/images/, then it is important that there is ample space to accommodate future Virtual Machines (eg. assignments) or future growth of file-systems.

Although you will be performing Logical Volume Management graphically in Investigation #1, we will be adjusting the sizes of lv_root and lv_home for this section via command line.

Perform the following operations to readjust size of lv_root and lv_home in f16host:

1. Make certain you are in your f16host system.
2. Open a terminal.
3. login in as super-user.
4. Issue the following Linux command to reduce the logical volume size of lv_home: lvreduce -r vg_f16host/lv_home --size 150G
5. Issue the following Linux command to increase the logical volume size of lv_root: lvextend vg_f16host/lv_root --size +25G
6. Issue the vgs, pvs, and lvs commands to verify new volume information for f16host.
7. Proceed to Investigation #1.

Investigation 1: How are LVMs are managed using system-config-lvm?

Perform this investigation on the VM named fedora2.

Screenshot of system-config-lvm in Fedora. Click to enlarge.

1. Let's learn to manage or administer our LVM graphically for our Virtual Machine (Fedora2).
   Fedora provides a tool called system-config-lvm to graphically administer LVM. It will appear on the menu as System>Administration>Logical Volume Management. Verify that this package is present, and install it if required (yum install system-config-lvm).

2. Use this tool to determine the current LVM configuration by clicking on the appropriate element and reading the properties in the right-hand panel -- write down the answers:
   1. What are the names and sizes of the PVs?
   2. What is the name and size of the VG?
   3. What are the names and sizes of the LVs?
   4. Is there any space in the VG which is not allocated to a LV?
3. Increase the size of the home filesystem to 2 GB:
   1. Click on the LV containing the home filesystem.
   2. Click on Edit Properties.
   3. Change the size to 2 GB and click Ok.
4. Create a new 2G LV (LV Properties: linear) containing an ext4 filesystem named lv_archive and mount it at /archive
   1. Click on Logical View.
   2. Click the Create New Logical Volume.
   3. Set the name, size, filesystem, and mount point.
   4. Click Ok.
5. Backup /etc into /archive

• Copy the files in /etc into the filesystem mounted at /archive
  (use the graphical tools or the command line. If using cp, remember to use the -R option).

6. Shrink the size of lv_archive to 1 GB.
7. Try shrinking / -- what happens? Why?

Investigation 2: How are LVMs are managed using Command-Line Tools

1. You are going to repeat the same LVM management operations (as your did with the fedora2 VM), but you will using command-line tools in the fedora 3 VM. Since the fedora3 VM only operates in command-line mode, you will need to refer to the "Logical Volume Management" link above.
2. Write down the exact commands used at each step, and record appropriate command output:
   1. Determine the current LVM configuration using the pvs, vgs, and lvs command.
   2. Grow the home filesystem to 2G using the command lvextend and resize2fs.
   3. Create a new 2G LV containing an ext4 filesystem and mount it at /archive (use lvcreate, mkfs, mount, edit the file /etc/fstab, and then reboot to confirm automatic mount).
   4. Copy the contents of /etc into /archive.
   5. Shrink lv_archive to 1G (use umount, resize2fs, lvreduce, and mount)

Investigation 3: How can a PV be added to an existing VG?

Add an additional 2 GB virtual disk to your fedora1 system, and use it as an additional physical volume:

1. Start virt-manager.
2. Shutdown fedora1 if it is running.
3. Open the console window for fedora1.
4. Select the menu option View>Details.
5. Click Add Hardware button at the bottom left-hand corner.
6. In the Adding new virtual hardware window that appears, select a Hardware Type of "storage" and click "Forward".
7. Make certain option "Managed or other existing storage" is selected. Click on the Browse button, then click on New Volume.
8. Give the new virtual disk file a name of fedora1b, a format of raw, with a Max Capacity and Allocation of 2000 MB. Click Finish.
9. Select the new virtual disk file fedora1b.img and click Choose Volume.
10. Select a device type of Virtio Disk.
11. Finish creating the new virtual disk by clicking Forward and then Finish.
12. Boot the system. You should now have both /dev/vda and /dev/vdb.
13. Record the size of the volume group and the amount of free space led downlight singapore(Hint: use a command that you learned in a previous lab).
14. Partition /dev/vdb with a single partition that fills the whole disk.
15. Check the messages printed when fdisk exits -- you may need to reboot the system in order for the new partition table to take effect.
16. Run this command to format the physical volume: pvcreate /dev/vdb1
17. Add the new physical volume to the existing volume group: vgextend nameOfVolumeGroup /dev/vdb1
18. Verify that the volume group is larger and has more free space.

Think!
The next part of this investigation is designed to encourage the student to research, think, and use some creativity in working around obstacles in order to solve a task. Research methods can include the Internet searches, etc...

Using that additional space, create a separate filesystem for /home:

1. Create the logical volume lv_home (1G ext4)
2. Find a way to move the contents of /home onto it.
3. Change your system configuration so that the new filesystem is mounted on /home from now on.

SELinux relabelling may be required
Your system may report that the files are not present in the new /home filesystem when they are clearly there. This is due to the Security-Enhanced Linux system (SELinux) preventing access to the files, because the files were tampered with (moved) and are no longer recognized as home directory content. You can fix this problem by restoring the file context labels so that SELinux accepts the files as valid home directory content: restorecon -r /home

Investigation 4: How can I use LVM to manage storage on my disk pack?

On your f16host (i.e. "disk pack"), using your choice of the GUI and/or command-line tools:

1. Create a new logical partition (NOT a logical volume!) - minimum 5G, leaving at least 10G free space in the extended partition.
2. Add that partition as a PV into the existing VG (using the commands you used in the previous investigation).
3. Grow the root filesystem to fill the available space.

Package Management

Investigation 5: How do you query the RPM database?

RPM maintains a database of installed software. This information is very useful to system administrators. In Lab 3, you queried that database using RPM with the -q argument. When you query the RPM database, you can separately specify:

• Which packages you want information about, using a select-option
• What information you want about those packages, using a query-option

Steps:

1. Using information from the man page for rpm, fill in this information:

Option	Meaning	Is this a select-option or a query-option?
-a	Select all packages	select-option
-l
-p filename'	Select this uninstalled package
-i	Show the package license, packager, URL, description, and other general information.
-f filename
packagename	Select just this package	select-option

Make sure that your lab notes answer the Investigation 5 question.

Investigation 6: How do you install and remove software with RPM?

1. Change to the directory on your Installation DVD containing the file: lynx-2.8.7-2.fc16.x86_64.rpm
2. Execute this command: rpm -i lynx-2.8.7-2.fc16.x86_64.rpm
3. Issue an RPM query to check that lynx is installed.
4. Issue this command: rpm -e lynx
5. Issue an RPM query to verify that lynx is no longer installed.
6. Issue this command: rpm -i BackupPC-3.1.0-16.fc16.noarch.rpm and note the result

Answer the Investigation 6 question.

Investigation 7: How do you install and remove software with yum?

Internet Connection
In order for yum to work you require a connection to the Internet. Establish this connection by using the browser to log into SeneNET

1. Change to your home directory.

1. Issue the command: yum install BackupPC and answer y to the question about installation.
   • Where did yum get the BackupPC software?
   • Why could yum install BackupPC when rpm couldn't?
2. Issue an RPM query to verify that BackupPC is installed.
3. Issue the command: yum remove BackupPC
4. Issue an RPM query to verify that BackupPC is no longer installed.
5. Install nled using yum.
6. Issue this command: yum info cups
   • Based on the result, do you think that cups is a useful package for your system? If not, try removing it.
7. Unused and unneeded software can present a security risk and ties up disk space needlessly. Find at least 4 other packages that you're not using on your system, and remove them. Be careful to ensure that removing those packages does not also remove other software that you do need.

Answer the Investigation 7 question.

Completing the lab

Time for a new backup!
If you have successfully completed this lab, make a new backup of your virtual machines. Remember to also make a backup of the new second virtual disk drive on fedora1 -- you now have two virtual disks on fedora1, and therefore two image files, and therefore will need two backup files.

Arrange proof of the following on the screen:

1. Two PVs on fedora1.
2. Separate /home filesystem (on an LV) in fedora1.
3. Larger /home on fedora2 and fedora3.
4. Unnecessary/unused packages have been deleted (list at least 4, and show that they are no longer installed).
5. Account created on fedora3 matching your Matrix account.
6. nled installed on the host (disk pack - main system f16host).
7. Answer to this question:
   • What is the license of the nautilus package?
8. Fresh backup of the virtual machines.

Preparing for the Quizzes

1. What is a VG? PV? LV?
2. What does yum do that rpm does not?
3. What is the total size of the "main" VG on your system?
4. How do you create a LV?
5. How do you delete an LV?
6. How would you add the disk partition /dev/sdb7 to your volume group "main"?
7. How would you increase the size of the root filesystem by 50 MB?