Pods Stuck in "Pending" State on DigitalOcean Kubernetes Cluster

Hi everyone,

I’m running a Kubernetes cluster on DigitalOcean, and I’m facing an issue where my pods are stuck in the “Pending” state and won’t start. This happened after I scaled my application to add more replicas.

Here’s my setup:

• Kubernetes version: 1.27
• Node pool: 3 nodes, each with 2 vCPUs and 4 GB RAM
• Application: Nginx-based with a Deployment manifest
• Storage: Using DigitalOcean Block Storage for persistent volumes

What I’ve observed:

1. Running kubectl describe pod <pod-name> shows the following events:

Warning FailedScheduling 30s (x3 over 1m) default-scheduler 0/3 nodes are available: insufficient memory.

1. Existing pods are running fine, but the new replicas cannot be scheduled.
2. The nodes themselves show low CPU usage (below 50%), but the memory usage is higher (around 80%).

What I’ve tried so far:

1. Checked resource requests and limits in my Deployment manifest. It looks like each pod requests 500Mi of memory and 0.5 CPU.
2. Reduced the number of replicas, which allowed some pods to start, but not all.
3. Restarted the cluster to see if it resolves any potential resource conflicts, but the issue persists.
4. Checked for taints and tolerations but didn’t find any that would block scheduling.

Questions I have:

1. Could this be related to DigitalOcean’s node pool configuration, and should I consider resizing my nodes?
2. Are there any tools or techniques I can use to better analyze and optimize resource allocation within my cluster?
3. Is this issue common when using DigitalOcean Kubernetes with Block Storage, and if so, how can I address it?

Any advice or suggestions would be greatly appreciated! Thanks in advance for your help.