LVM – Setup and configure Physical Volumes in RHEL 6/Centos 6 – Part 1

Welcome to Part 1 of this series of 4 articles detailing how to setup and configure multiple filesystems running on LVM partitions. Each article will cover a specific topic, per the below:

Part 1 – Setup and configure Physical Volumes
Part 2 – Setup and configure Volume Groups
Part 3 – Setup and configure Logical Volumes
Part 4 – Setup and configure Filesystems

In Part 1 I will cover how to setup and setup Physical Volumes on three empty disks that have been attached to my test server, which is a VMware VM running Centos 6.6.

Without further ado, let’s proceed. So the first thing to do is ensure LVM is actually installed on your system – my minimal install of Centos 6 had LVM pre-installed however we must still check in order to ensure we can perform all the necessary tasks to complete our goal.

To ensure lvm installed on your server, run the following command:

rpm -qa |grep -i lvm

Running this on my system confirmed that LVM already installed and is version 2:

[root@lnx-svr-01 ~]# rpm -qa |grep -i lvm
lvm2-libs-2.02.111-2.el6.x86_64
lvm2-2.02.111-2.el6.x86_64
[root@lnx-svr-01 ~]#

If it isn’t installed run the following command and enter Yes to any prompts:

[root@lnx-svr-01 ~]#  yum install lvm2*

Next thing to check is our current disk/partition layout by running fdisk -l:

[root@lnx-svr-01 ~]# fdisk -l

Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00099a71

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64        2611    20458496   8e  Linux LVM

Disk /dev/sdb: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sdd: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sdc: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_root: 18.8 GB, 18798870528 bytes
255 heads, 63 sectors/track, 2285 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_swap: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

[root@lnx-svr-01 ~]#

We have 4 disks attached to this server, which happens to be a VMware VM. The screenshot below shows the disks in question, Hard disk 1 – Hard disk 4:

20150611165654

The four disks are /dev/sda, /dev/sdb, /dev/sdc and /dev/sdd. There are no partitions yet on /dev/sdb/dev/sdd, these disks are empty. You can see that /dev/sda2 has an LVM partition already as the Id is 8e, which denotes an LVM partition. The System heading confirms that it is indeed Linux LVM.

We will now create the partitions /dev/sdb1, /dev/sdc1 and /dev/sdd1. I will start the process by partitioning /dev/sdb:

[root@lnx-svr-01 ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x2ac771b0.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): m
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-652, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-652, default 652):
Using default value 652

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): L

 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris
 1  FAT12           39  Plan 9          82  Linux swap / So c1  DRDOS/sec (FAT-
 2  XENIX root      3c  PartitionMagic  83  Linux           c4  DRDOS/sec (FAT-
 3  XENIX usr       40  Venix 80286     84  OS/2 hidden C:  c6  DRDOS/sec (FAT-
 4  FAT16 <32M      41  PPC PReP Boot   85  Linux extended  c7  Syrinx
 5  Extended        42  SFS             86  NTFS volume set da  Non-FS data
 6  FAT16           4d  QNX4.x          87  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS       4e  QNX4.x 2nd part 88  Linux plaintext de  Dell Utility
 8  AIX             4f  QNX4.x 3rd part 8e  Linux LVM       df  BootIt
 9  AIX bootable    50  OnTrack DM      93  Amoeba          e1  DOS access
 a  OS/2 Boot Manag 51  OnTrack DM6 Aux 94  Amoeba BBT      e3  DOS R/O
 b  W95 FAT32       52  CP/M            9f  BSD/OS          e4  SpeedStor
 c  W95 FAT32 (LBA) 53  OnTrack DM6 Aux a0  IBM Thinkpad hi eb  BeOS fs
 e  W95 FAT16 (LBA) 54  OnTrackDM6      a5  FreeBSD         ee  GPT
 f  W95 Ext'd (LBA) 55  EZ-Drive        a6  OpenBSD         ef  EFI (FAT-12/16/
10  OPUS            56  Golden Bow      a7  NeXTSTEP        f0  Linux/PA-RISC b
11  Hidden FAT12    5c  Priam Edisk     a8  Darwin UFS      f1  SpeedStor
12  Compaq diagnost 61  SpeedStor       a9  NetBSD          f4  SpeedStor
14  Hidden FAT16 <3 63  GNU HURD or Sys ab  Darwin boot     f2  DOS secondary
16  Hidden FAT16    64  Novell Netware  af  HFS / HFS+      fb  VMware VMFS
17  Hidden HPFS/NTF 65  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE
18  AST SmartSleep  70  DiskSecure Mult b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 75  PC/IX           bb  Boot Wizard hid fe  LANstep
1c  Hidden W95 FAT3 80  Old Minix       be  Solaris boot    ff  BBT
1e  Hidden W95 FAT1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@lnx-svr-01 ~]#

Perform the same step for hard disks /dev/sdc – /dev/sdd:

fdisk /dev/sdc
fdisk /dev/sdd

Once you partitioned all the disks run fdisk -l again to see the new partition layout:

[root@lnx-svr-01 ~]# fdisk -l

Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00099a71

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64        2611    20458496   8e  Linux LVM

Disk /dev/sdb: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x2ac771b0

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         652     5237158+  8e  Linux LVM

Disk /dev/sdd: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x8b19e7ca

   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1               1         652     5237158+  8e  Linux LVM

Disk /dev/sdc: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xfd839be4

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1        1305    10482381   8e  Linux LVM

Disk /dev/mapper/VolGroup-lv_root: 18.8 GB, 18798870528 bytes
255 heads, 63 sectors/track, 2285 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_swap: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

[root@lnx-svr-01 ~]#

As you can see from the output /dev/sdb1, /dev/sdc1 and /dev/sdd1 represent the newly created partitions on each disk (1 = first partition). They are all identified as 8e Linux LVM partitions.

Next, we are going to setup the physical volumes on our newly created partitions by running the pvcreate command:

pvcreate /dev/sdb1 /dev/sdc1 /dev/sdd1

Results from pvcreate:

[root@lnx-svr-01 ~]# pvcreate /dev/sdb1 /dev/sdc1 /dev/sdd1
  Physical volume "/dev/sdb1" successfully created
  Physical volume "/dev/sdc1" successfully created
  Physical volume "/dev/sdd1" successfully created
[root@lnx-svr-01 ~]#

Please note that pvremove deletes the physical volumes, run it for the purposes of learning:

[root@lnx-svr-01 ~]# pvremove /dev/sdb1 /dev/sdc1 /dev/sdd1
  Labels on physical volume "/dev/sdb1" successfully wiped
  Labels on physical volume "/dev/sdc1" successfully wiped
  Labels on physical volume "/dev/sdd1" successfully wiped
[root@lnx-svr-01 ~]#

Then re-run pvcreate to re-create the physical volumes:

[root@lnx-svr-01 ~]# pvcreate /dev/sdb1 /dev/sdc1 /dev/sdd1
  Physical volume "/dev/sdb1" successfully created
  Physical volume "/dev/sdc1" successfully created
  Physical volume "/dev/sdd1" successfully created
[root@lnx-svr-01 ~]#

Now run pvdisplay to display all the physical volumes:

[root@lnx-svr-01 ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               VolGroup
  PV Size               19.51 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              4994
  Free PE               0
  Allocated PE          4994
  PV UUID               tx5fGZ-LURm-Bqgq-Jxqz-AuJD-IWgl-YMxPle

  "/dev/sdb1" is a new physical volume of "4.99 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb1
  VG Name
  PV Size               4.99 GiB
  Allocatable           NO
  PE Size               0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               OpA0C8-wv7K-0cZT-3zHW-GXeb-YLM8-hWbRjL

  "/dev/sdc1" is a new physical volume of "10.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdc1
  VG Name
  PV Size               10.00 GiB
  Allocatable           NO
  PE Size               0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               VC7As8-pB3U-GGqa-l0xg-NIVj-jv7l-dTGGHl

  "/dev/sdd1" is a new physical volume of "4.99 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdd1
  VG Name
  PV Size               4.99 GiB
  Allocatable           NO
  PE Size               0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               xKOs8i-UQy1-mpvu-8Hhl-zjF4-FYjb-w4DwSu

[root@lnx-svr-01 ~]#

The output above shows all of the physical volumes on this system.

This is then end of Part 1. Please go to Part 2, to setup and configure Volume Groups.

References:
How to Create LVM Partition in RHEL 6 / CentoOS
Linux Basics – LVM (Logical Volume Manager) Tutorial
How to Install LVM on Linux and Disk Operations
A Beginner’s Guide To LVM
How To Create LVM Using vgcreate, lvcreate, and lvextend lvm2 Commands

Setup and Configure SMTP Server on Windows Server 2012

The steps to setup and configure an SMTP Server or mail relay on Windows Server 2012 are very similar to those for Windows Server 2008 except for a few differences. Confusion has arisen due to GUI changes in Server 2012, which has led me to create this post to help anyone that requires explicit step-by-step instructions.

Note: The exact steps for installing SMTP Server on Windows Server 2008 can be found in this previous post of mine.

Installing the SMTP feature

1. Click on the Server Manager icon in the bottom left-hand corner to load the Server Manager Dashboard:

20141101005404

Alternatively, click on the Powershell icon to its right and enter servermanager.exe at the prompt to load the Server Manager Dashboard:

PS C:\Users\Admin> servermanager.exe

2. When the Server Manager Dashboard loads, click on Add roles and features in the center pane as highlighted below:

20141101010748

The Add Roles and Features Wizard will load, click Next to go past the initial Before You Begin Page:

20140924014048

3. In the Installation Type section, select Role-based or feature-based installation and click Next:

20140924014128

4. In the Server Selection section, select your server, in my example below, my server is called 2012, then click Next to proceed:

20140924014215

5. In the Server Roles section select Web Server (IIS) as highlighted below and click Next:

20140924014306

Doing so will initiate a prompt to install the required IIS Management Console. Ensure you check the Include management tools (if applicable) box per the below and click Add Features to proceed:

20140924014441

6. In the Features section, select the SMTP Server feature then click Install to proceed:

20140924014555

You will prompted to install services and features required by the SMTP Server. Ensure you check the Include management tools (if applicable) box per the below and click Add Features to proceed:

20140924014632

7. You will now be presented with the Web Server Role (IIS) section. Click Next to proceed:

20140924014741

In the Role Services section, scroll down and under Management Tools select the services to match those checked in screenshot below then click Next to proceed:

20140924015141

8. The Confirmation section will show all the role and feature configuration options you previously selected:

20140924015230

Click Install to start the installation:

20140924015320

The installation should complete shortly. You nay need to reboot your server to fully complete the installation.

Configuring the SMTP Server

The next step is to configure SMTP. To do so we will need to open Internet Information Services (IIS) Manager 6. 10. Click on the Server Manager icon per step 1 to load the Server Manager Dashboard. Then click Tools and then click on Internet Information Services (IIS) 6.0 Manager to load IIS Manager 6:

20140924022404

9. In IIS 6 Manager, expand the server name, in my example below it is 2012, then right-click on SMTP Server and select Properties:

20140924022612

10. In the General tab, unless you want the SMTP Server to use a specific IP address,  leave the settings as they are so that the IP address is set to (All Unassigned):

20140924023027

11. To proceed, click on the Access tab:

20140924023125

12. Click on the Authentication button and ensure Anonymous access is checked and then click OK:

20140924023219

13. Once back in the Access tab, click on the Connection button. Select Only the list below and then click Add. Enter 127.0.0.1 as the IP address and then click OK:

20140924023339

The Connection setting controls which computers can connect to the SMTP server and send mail. By granting only localhost (127.0.0.1) access, limits only the server itself the ability to connect to the SMTP server. This is a requirement for security. Click OK to return to the Access tab and then click on the Relay button. Enter 127.0.0.1 as the IP address and then click OK:

20140924023442

The Relay section determines which computers can relay mail through this SMTP server. By only allowing the localhost IP address (127.0.0.1) relay permissions it means that only the server itself can relay mail. Conversely, it prevents the SMTP server from being an open relay and being used to send unsolicited spam email by other computers on the internet, which could lead to the SMTP server being blacklisted.

14. Next, go to the Messages tab. Here you can enter an email address where copies of non-delivery reports are sent to. You can also configure the location of the Badmail director, however, the default setting should suffice:

20140924023556

15. Next, go to the Delivery tab:

20140924023648

16. Click on the Outbound Security button and ensure Anonymous access is selected. As the only server that can connect and relay mail through the SMTP server is localhost this security settings is fine:

20140924023728

17. Click OK to return to the Delivery tab and then click on Outbound Connections. Leave the defaults as they are:

20140924023810

18. Click OK to return to the Delivery tab and then click on Outbound Connections, then click on the Advanced button:

20140924023903

Here you will need to enter the fully-qualified domain name of the SMTP server. This will be the host name or A record that has been created in your DNS zone file. This is straight-forward to do but you will have to confirm how you do this with the party that manages DNS for your domain. I have entered mail.vsysad.com as this is fully-qualified. If you click on the Check DNS button you can confirm whether your chosen name resolves successfully. In my case it does as I see the following:

20140924023952

19. Click OK and then OK again to exit the SMTP Virtual Server Properties. You can also perform this test by running nslookup to confirm the existence of the host name as well as confirming the IP address it resolves to – which should the IP address of your server:

20141105035933

You can also load the nslookup command from PowerShell also:

20141105040434

Please note that DNS is crucial to successful email delivery. If your SMTP server cannot resolve the domains it is trying to send messages to then it will fail. Ensure that the DNS servers you have configured are able to resolve DNS queries successfully. From the above screenshot you can see that the DNS server I have configured, cachens2.dfw1.rackspace.com, was able to successfully resolve my SMTP server’s hostname, mail.vsysad.com. This is one of Rackspace’s many DNS servers and I am 100% confident it works fine.

The reason I am highlighting this is because if your SMTP Server sits within a corporate network it will likely use an internal DNS server. Often these are only configured to resolve internal namespaces therefore resolving external hostnames may fail. Also, firewall rules may block your SMTP Server from querying any DNS servers so please check and ensure DNS queries are resolved successfully and if not make sure it get fixed before going onto the testing phase below.

Another very important point about DNS is that you must ensure that you have a PTR record for reverse DNS lookups configured. The PTR record allows your SMTP Server’s public IP address to be resolved back to your hostname. Some of the major email providers perform revers DNS lookups of  mail servers connecting to them as a security measure to check their credibility or reputation. Your web host should have a control panel that allows you to configure reverse DNS if you have a dedicated public IP address. Not having a PTR record will not guarantee email delivery failure but it will very likely delay email delivery and at worst may result in your messages being blocked and your host being blacklisted. I highly recommend you you configure a PTR record for your server.

Follow the instructions in this post which shows you how to verify correct DNS configuration using the SMTPDIAG tool.

20. The last configuration step will be to set the SMTP Service to Automatic so that it automatically starts when the server boots up. Open up the Powershell console and run the command below to enable this setting:

PS C:\Users\Admin> set-service smtpsvc -StartupType Automatic

Then run the command below to confirm that the service is actually running:

PS C:\Users\Admin> get-service smtpsvc

Status   Name               DisplayName
------   ----               -----------
Running  smtpsvc            Simple Mail Transfer Protocol (SMTP)

If the SMTP Service is not running the command will return a status of Stopped. If that is the case then run the command below to start it:

PS C:\Users\Admin> start-service smtpsvc

We are now ready to test the configuration.

 Testing the SMTP Server

The next step is to verify that the SMTP server is able to send email successfully. To do this follow the steps below:

21. Create a text file on your desktop called email.txt and paste the following into it, remembering to change the email address information to reflect your own details:

From: blog@yourdomain.com
To: email@yourdomain.com
Subject: Email test

This is the test body of the email

.

22. Save the changes to email.txt and then copy the file to C:\inetpub\mailroot\Pickup. The SMTP server monitors this folder and when it detects the email.txt file, it will read the contents and send the email to the address in the To: section. This should happen almost immediately.

23. Check the email address the email was sent to and it should arrive shortly – the email was sent to my Gmail account:

20130429184511

A much easier, alternative way of doing this is to use PowerShell. To do so, launch the console and simply run the command below, ensuring that you complete the sending and receiving email addresses plus the subject and body text:

PS C:\Users\admin> Send-MailMessage -SMTPServer localhost -To xxxxx@gmail.com -From blog@vsysad.com -Subject "This is a test email" -Body "Hi Japinator, this is a test email sent via PowerShell"

The above command sent an email to my Gmail account, a screenshot of the email generated is below:

20131031223718

You can save the above command in a file with a .ps1 (PowerShell) file extension and run it whenever you need to test sending/routing of mail.

Apparently there’s more than one way to skin a cat. There’s also another way to test your mail relay server. You can use an email web form application which is similar to a contact us page on a website which allows you to post some feedback, which then uses an SMTP Server to deliver the messages to specific email contacts such as info@yourdomain.com that monitor this information. See this post to learn how to do this using an ASP.NET 4.0 C# email web form application.

That’s all there is to it! Now you have a fully functioning STMP server that can successfully send emails. Many of the companies that I have worked with use this method to send emails generated by their web applications.

If emails are not being successfully delivered you may notice that messages are building up in specific SMTP folders. Visit this post to understand the purpose of each SMTP folder and how to approach issues when messages are queuing up in those folders.

References:
How to test outbound mail flow with a file in the Pickup folder
IIS SMTP Folder Structure and how SMTP service works