DISCLAIMER : Please note that blog owner takes no responsibility of any kind for any type of data loss or damage by trying any of the command/method mentioned in this blog. You may use the commands/method/scripts on your own responsibility.If you find something useful, a comment would be appreciated to let other viewers also know that the solution/method work(ed) for you.

How to reduce LVM partition size in RHEL and CentOS

Sometimes when we are running out of disk space in our Linux box and if partition created on LVM , then we can make some free space in the volume group by reducing the LVM using lvreduce command.In this article we will discuss the required steps to reduce the size of LVM safely on CentOS and RHEL Servers, Below steps are eligible when the LVM partition is formated either as ext
Scenario : Suppose we want to reduce /home by 2GB which is on LVM partition & formated as ext4.
[root@cloud ~]# df -h /home/
 Filesystem            Size  Used Avail Use% Mounted on
 /dev/mapper/vg_cloud-LogVol00
                       12G   9.2G  1.9G  84%  /home

Step:1 Umount the file system

Use the beneath umount command
[root@cloud ~]# umount /home/

Step:2 check the file system for Errors using e2fsck command.

[root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00
 e2fsck 1.41.12 (17-May-2010)
 Pass 1: Checking inodes, blocks, and sizes
 Pass 2: Checking directory structure
 Pass 3: Checking directory connectivity
 Pass 4: Checking reference counts
 Pass 5: Checking group summary information
 /dev/mapper/vg_cloud-LogVol00: 12/770640 files (0.0% non-contiguous), 2446686/3084288 blocks
Note: In the above command e2fsck , we use the option ‘-f’ to forcefully check the file system, even if the file system is clean.

Step:3 Reduce or Shrink the size of /home to desire size.

As shown in the above scenario, size of /home is 12 GB , so by reducing it by 2GB , then the size will become 10GB.
[root@cloud ~]# resize2fs /dev/mapper/vg_cloud-LogVol00 10G
 resize2fs 1.41.12 (17-May-2010)
 Resizing the filesystem on /dev/mapper/vg_cloud-LogVol00 to 2621440 (4k) blocks.
 The filesystem on /dev/mapper/vg_cloud-LogVol00 is now 2621440 blocks long.

Step:4 Now reduce the size using lvreduce command.

[root@cloud ~]# lvreduce -L 10G /dev/mapper/vg_cloud-LogVol00
 WARNING: Reducing active logical volume to 10.00 GiB
 THIS MAY DESTROY YOUR DATA (filesystem etc.)
 Do you really want to reduce LogVol00? [y/n]: y
 Reducing logical volume LogVol00 to 10.00 GiB
 Logical volume LogVol00 successfully resized

Step:5 (Optional) For the safer side, now check the reduced file system for errors

[root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00
 e2fsck 1.41.12 (17-May-2010)
 Pass 1: Checking inodes, blocks, and sizes
 Pass 2: Checking directory structure
 Pass 3: Checking directory connectivity
 Pass 4: Checking reference counts
 Pass 5: Checking group summary information
 /dev/mapper/vg_cloud-LogVol00: 12/648960 files (0.0% non-contiguous), 2438425/2621440 blocks

Step:6 Mount the file system and verify its size.

[root@cloud ~]# mount /home/
 [root@cloud ~]# df -h /home/
 Filesystem            Size  Used Avail Use% Mounted on
 /dev/mapper/vg_cloud-LogVol00
                       9.9G  9.2G  208M  98% /home
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Add Multiple IP address to single NIC in Suse Linux - Azure

Some of you might wondering why would we assign multiple IP addresses to single Network card. There can be many reasons. Say for example, you are doing some testing on your Linux box that requires two or more network cards. Would you buy new one? No, It is not necessary to buy a new one.

You can set multiple IP series, for example 192.168.1.0, 192.168.2.0, 192.168.3.0 etc., for a network card, and use all of them at the same time. Sounds useful? Of course, it is!

This method might be helpful when setting up Internet sharing servers, like Squid proxy.

To add multiple IP address for SUSE Linux VM on Azure, you may can take reference from below steps:

Login Azure portal then navigate to VM - Networking - Network Interface, then click the NIC

Click "Add" to add secondary DIP with static type

Login the VM then run "yast" to add the second IP address
$ sudo yast

Press "F4 Edit" – "F3 Add" then input the assigned IP address from the portal and follow the steps to press F10 Next|OK to save and exit
        

Now the VM has added the second IP address
$ sudo ifconfig
$ ip a

And it's able to ping from another VM within same VNET

Now you have successfully configured the multiple address fro single NIC.

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Install AzCopy on Linux - Fastest way to copy in Azure

AzCopy is a command-line utility designed for copying data to/from Microsoft Azure Blob, File, and Table storage, using simple commands designed for optimal performance. You can copy data between a file system and a storage account, or between storage accounts.

There are two versions of AzCopy that you can download. AzCopy on Linux is built with .NET Core Framework, which targets Linux platforms offering POSIX style command-line options. AzCopy on Windows is built with .NET Framework, and offers Windows style command-line options.

This article covers AzCopy on Linux.

Installation on Linux


AzCopy on Linux requires .NET Core framework (version 2.0) on the platform. See the installation instructions below 

Install and enable the .NET SDK


After registering with the Subscription Manager and enabling the .NET Core channel, you are ready to install and enable the .NET SDK.

In your command prompt, run the following commands: 

yum install rh-dotnet20 -y scl enable rh-dotnet20 bash

Once you have installed .NET Core, download and install AzCopy.

wget -O azcopy.tar.gz https://aka.ms/downloadazcopyprlinux tar -xf azcopy.tar.gz sudo ./install.sh

You can remove the extracted files once AzCopy on Linux is installed. Alternatively if you do not have superuser privileges, you can also run AzCopy using the shell script 'azcopy' in the extracted folder.

The basic syntax for AzCopy commands is: 

azcopy --source <source> --destination <destination> [Options]

The following examples demonstrate various scenarios for copying data to and from Microsoft Azure Blobs and Files. Refer to the azcopy --help menu for a detailed explanation of the parameters used in each sample.

If any user face issue while running azcopy command which asks for dotnet files, enter the below line in the users .bashrc file.

source scl_source enable rh-dotnet20

If  a user oracle needs to run this command, then add the below line to the oracle .bash_profile under PATH section

/opt/rh/rh-dotnet20/root/usr/bin/

Add the below line in the script if you would use azcopy in a shell script.

source scl_source enable rh-dotnet20

 Now type azcopy in the server and it shows the available options to use, you can explore the options and use this command as required.
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