Check if the Disk is Full

To check if the disk is full, use the df command:

df -h

• -h: Displays sizes in human-readable format (e.g., GB, MB).
• Look for the % column to see disk usage.

To find which directories are consuming the most space, use du:

du -h --max-depth=1 / | sort -h

• Replace / with the directory you want to analyze.

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What is using memory resources?

To check memory usage, use the free command:

free -h

• -h: Displays memory usage in human-readable format.

For a more detailed view, use top or htop. Look at the %MEM column to see which processes are using the most memory.

top

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Check memory paging status

To check if the system is paging or swapping, use:

vmstat 1

• Look at the si (swap in) and so (swap out) columns. Non-zero values indicate swapping.

Alternatively, check swap usage directly:

swapon --show

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What is using CPU resources?

To see which processes are consuming the most CPU, use:

top

Look at the %CPU column.

For a more user-friendly interface, use htop (if installed):

htop

To view CPU usage over time:

sar -u 1 5

Requires the sysstat package.

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What is using GPU resources?

If you have an NVIDIA GPU, use the nvidia-smi command:

nvidia-smi

Displays GPU usage, memory usage, and running processes. For AMD GPUs, use:

radeontop

Requires the radeontop package.

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What shared memory segments are being used?

To list shared memory segments, use:

ipcs -m

• -m: Displays shared memory segments.

To remove unused shared memory segments:

ipcrm -m <shmid>

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What is using port 8080?

To check which process is using port 8080, use:

sudo lsof -i :8080

• -i :8080: Filters for processes using port 8080.

Alternatively, use netstat:

sudo netstat -tuln | grep 8080

• -tuln: Displays TCP/UDP connections in numeric format.

Or with ss:

sudo ss -tuln | grep 8080

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What so files are being used by this process?

To list the shared object (.so) files used by a process, use:

sudo lsof -p <pid> | grep '\.so'

• Replace <pid> with the process ID.

Alternatively, use ldd to check the shared libraries of an executable:

ldd /path/to/executable

What Hypervisor Am I Running On

To determine the identity and status of the parent hypervisor on a VM, you can use different methods depending on the operating system and the virtualization technology being used. Here’s a breakdown of how to do it:

Identify the Hypervisor - check for Hypervisor Vendor

cat /sys/class/dmi/id/product_name

This will return something like:

• VMware Virtual Platform → VMware ESXi
• Virtual Machine → Microsoft Hyper-V
• KVM or QEMU → KVM/QEMU
• Parallels → Parallels
• Xen → Xen

Or using virt-what (if installed)

sudo virt-what

Output examples:

• kvm → Running on KVM
• vmware → Running on VMware
• hyperv → Running on Microsoft Hyper-V
• xen → Running on Xen

Check the Hypervisor Status. Once you've identified the hypervisor, you may want to check its status.

If you are on a VM running on VMware, you can query vSphere using (Run this on the ESXi host, not the VM):

esxcli system version get

Or from the VM - if vmware-toolbox-cmd is installed, this checks communication with the ESXi host.

vmware-toolbox-cmd stat hosttime

On KVM/QEMU

Check if KVM is running on the host:

sudo systemctl status libvirtd

Or check virtualization capabilities:

lsmod | grep kvm