Add new post about shrinking ESXi VMDK disks

content/posts/shrink-vmdk.md

@@ -0,0 +1,81 @@
++++
+date = '2025-10-12T13:41:47+02:00'
+title = 'Shrink VMDK safely'
+description = "Thanwer's Blog Post about how to safely resize a VMDK file"
+tags = [
+    "GNU/Linux",
+    "Tools",
+    "ESXi",
+]
+canonical = "/posts/shrink-vmdk"
++++
+
+I recently was tasked to convert a couple physical servers to virtual machines.
+
+The physical servers basically had 2x 500GB SSDs in a RAID1 configuration, and the total used space was around 40GB.
+
+To optimize the storage for the virtual machines, I needed to resize the VMDK files accordingly. This process involves several steps to ensure data integrity and minimize downtime.
+
+Here I document the steps I took to safely resize a VMDK file, without modifying the virtual machine description file (VMX).
+
+## Step 1: Prepare the physical server
+
+Before starting, I did the basic preparation on the physical server:
+
+- As always, create a full backup of the server, just in case something goes wrong
+- Clean up unnecessary files to reduce the used space
+- Resize the partitions and filesystems to reduce the used space to the smallest possible size (in my case, I resized the partitions to 64GB to have some buffer space)
+
+![Gparted result](/images/vmdk-gparted-1.jpg)
+
+## Step 2: Convert the physical server to a virtual machine
+
+I used Clonezilla to convert the physical server to a virtual machine.
+This process was simply:
+
+- Boot the physical server with the Clonezilla live CD
+- Follow the wizard and choose the mode "remote-source" to send the image to a remote server
+- On the target virtual machine, boot with the Clonezilla live CD and choose the mode "remote-dest" to receive the image from the physical server
+- Inform the IP address of the physical server and start the process
+
+> Important: In this first step, I created a VMDK file with the same size as the physical disk (in my case, 500GB).
+
+![ESXi Disks](/images/vmdk-disks.jpg)
+
+## Step 3: Resize the VMDK file
+
+Now here is the tricky part, resizing the VMDK file without modifying the VMX file.
+
+Many tutorials suggest to access the ESXi host via SSH and directly modify the VMX file using a text editor.
+
+I found it to be very risky, as a small mistake can lead to a non-bootable virtual machine. I lost many attempts this way.
+
+So instead, I found a method that works without modifying the VMX file:
+
+Use Clonezilla again, to clone the virtual machine to a new virtual machine with a smaller disk size.
+
+This time we are going to use local disks, so we need to create a new virtual machine with a smaller disk size (in my case, 64GB).
+
+![Disks on ESXi](/images/clonezilla-1.jpg)
+
+![Clonezilla local source](/images/clonezilla-2.jpg)
+
+When asked about the partition table, choose the option "-k1" to keep the partition table as is.
+
+![Clonezilla partition table](/images/clonezilla-3.jpg)
+
+When asked about the mode, choose "Expert"
+
+![Clonezilla expert mode](/images/clonezilla-4.jpg)
+
+Then, enable the option "-icds" to ignore the disk size.
+
+![Clonezilla ignore disk size](/images/clonezilla-5.jpg)
+
+After following the rest of the wizard, the cloning process will start.
+
+![Clonezilla cloning](/images/clonezilla-6.jpg)
+
+After the process is complete, you will have a new virtual machine with a smaller disk size, and the same data as the original virtual machine.
+
+This will leave you with the original VMDK file, and a smaller one. After verifying that the new virtual machine works correctly, you can delete the original one to free up space.