When examining your EC2 instance details, the Root Device: EBS indication means your entire root volume is indeed hosted on Elastic Block Store (EBS). This is the most common configuration for persistent storage in AWS. The presence of EBS Optimized: false simply means your instance isn't using dedicated throughput for EBS volumes - it doesn't affect data persistence.

Based on your df -h output:

/dev/xvda1            7.9G  1.7G  6.2G  22% /
tmpfs                 298M     0  298M   0% /dev/shm

And your mount output:

/dev/xvda1 on / type ext4 (rw,noatime)
tmpfs on /dev/shm type tmpfs (rw)

We can confirm:

• /dev/xvda1 is your EBS root volume (persistent)
• tmpfs is RAM-based temporary storage (ephemeral)

To detect any available ephemeral storage (instance store) volumes that might not be mounted:

lsblk
NAME    MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   8G  0 disk 
└─xvda1 202:1    0   8G  0 part /

If you see additional devices like xvdb, xvdc etc. without mount points, those would be available ephemeral storage devices.

If your instance type includes ephemeral storage (like m3.large), you might see:

sudo file -s /dev/xvdb
/dev/xvdb: data

To format and mount it:

sudo mkfs -t ext4 /dev/xvdb
sudo mkdir /mnt/ephemeral
sudo mount /dev/xvdb /mnt/ephemeral

Your Apache config and Perl app files (/etc/apache2, /var/www) are on persistent EBS storage and will survive instance stops/restarts. Any data written to /dev/shm (tmpfs) or manually mounted ephemeral storage would be lost.

For complete confirmation, check your EBS volumes in AWS Console or via CLI:

aws ec2 describe-volumes --filters Name=attachment.instance-id,Values=your-instance-id

---

When examining your EC2 instance details, the Root Device: EBS indication means your entire root volume is indeed EBS-backed. This is good news for persistence - all your system files, Apache configurations, and Perl applications will survive instance stops/reboots.

From your df -h output:

Filesystem            Size  Used Avail Use% Mounted on
/dev/xvda1            7.9G  1.7G  6.2G  22% /

This shows your root filesystem is mounted at /dev/xvda1 (an EBS volume). The absence of other mounted devices suggests you're not currently using any instance store (ephemeral) volumes.

To check for available ephemeral storage that might not be mounted:

lsblk

Sample output might show:

NAME    MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   8G  0 disk 
└─xvda1 202:1    0   8G  0 part /
xvdb    202:16   0  50G  0 disk 

Here, xvdb represents available ephemeral storage that isn't mounted.

The EBS Optimized: false setting simply means your instance isn't using dedicated throughput for EBS volumes. This doesn't affect data persistence - it only impacts performance. For production workloads, consider enabling EBS optimization.

If you wanted to utilize ephemeral storage, here's how to mount it:

sudo mkfs -t ext4 /dev/xvdb
sudo mkdir /ephemeral
sudo mount /dev/xvdb /ephemeral

Remember to add to /etc/fstab if you want it mounted at boot:

/dev/xvdb  /ephemeral  ext4  defaults,nofail  0  2

• EBS volumes persist independently of instance state
• Instance store volumes are ephemeral and deleted when instance stops/terminates
• Root device type determines where your OS lives (EBS or instance store)

Here's a simple bash script to check storage types:

#!/bin/bash

echo "Checking storage devices..."
lsblk -d -o NAME,ROTA,TYPE,SIZE,MODEL

echo -e "\nMounted filesystems:"
df -hT | grep -v tmpfs

echo -e "\nEBS volumes attached (via AWS CLI):"
aws ec2 describe-volumes --filters Name=attachment.instance-id,Values=$(curl -s http://169.254.169.254/latest/meta-data/instance-id) --query 'Volumes[*].{ID:VolumeId,Type:VolumeType,Size:Size}' --output table