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Chapter 13: Amazon EBS (Elastic Block Store)

Interview Questions

These EBS questions surely come up in cloud interviews. Explain the resize commands in order – the interviewer sees your hands-on experience.

Q1. What is the difference between EBS and instance store?
EBS is persistent network-attached storage that survives stop/start and can be snapshotted. Instance store is temporary disk on the physical host; data is lost when the instance stops or terminates.
Q2. Can you attach an EBS volume to an instance in another AZ?
No. Create a snapshot, then create a new volume from it in the target AZ (or copy the snapshot to another region).
Q3. Compare gp3 and gp2.
gp2 performance scales with size (3 IOPS/GiB, burst to 3,000). gp3 gives a 3,000 IOPS / 125 MiB/s baseline regardless of size, lets you provision more independently, and is usually cheaper.
Q4. How do you increase the root volume size without downtime?
Modify the volume in the console, then sudo growpart /dev/nvme0n1 1, then sudo xfs_growfs -d / (XFS) or sudo resize2fs /dev/nvme0n1p1 (ext4); verify with df -hT.
Q5. Why do we use UUID and nofail in /etc/fstab?
NVMe device names can change between boots; the UUID is stable. nofail lets the system boot even if the volume is missing.
Q6. Are EBS snapshots full or incremental?
Incremental — only changed blocks after the first snapshot are stored, but each snapshot can restore the full volume.
Q7. What are st1 and sc1 used for?
HDD volumes for large sequential workloads: st1 for throughput-heavy data like logs/big data, sc1 for cold, rarely accessed data. Neither can be a boot volume.

Extended teaching notes

Why this lesson matters

Cloud security is mostly IAM, network exposure, logging and secure defaults. The shared responsibility model means the provider patches the metal; you patch what you configure.

  • No public databases or public admin panels.
  • Roles / OIDC instead of long-lived access keys.
  • CloudTrail / Activity Logs / Audit Logs on and retained.
  • S3/Blob/GCS: Block Public Access; encrypt; least privilege.

Mini case study

Suppose we are on a purple-team exercise for an Indian mid-size company (sample data). Red notes a technique from this lesson against a lab clone. Blue must show the control that stops it, the log that would have fired, and the ticket that hardens production. That is the standard this course trains you for.

Defender's worksheet (do this today)

  1. Write the lesson title, date and the exact lab target you are allowed to use.
  2. List three owned systems (VMs, apps, or cloud accounts) where this lesson applies.
  3. Run one safe check from the lesson on a lab system only. Paste the command and output.
  4. Write a two-sentence fix you would give a teammate.
  5. Name one related public advisory (CERT-In, CISA, NVD, or a vendor bulletin) with its date.

Indian workplace (sample data)

Suppose we are a junior analyst at Infosys, TCS, Wipro or a fintech SOC in Bengaluru/Pune. Turn this lesson into one checklist item with an owner, a due date and a place to store evidence (ticket + screenshot).

Global practice

Compare your notes with OWASP, CIS Benchmarks, NIST CSF/IR guidance or a cloud Well-Architected security question. Write five lines on what overlaps.

Everyday analogy

Explain the risk and the fix to a family member without jargon. If they can repeat the warning, you understand it well enough to teach juniors.

Key terms

  • Control: a safeguard (patch, config, process, detection).
  • Finding: a weakness backed by evidence.
  • Remediation: the fix plus how you verified it.
  • Scope: systems you have written permission to touch.
  • Least privilege: only the access the task needs.
  • Defence in depth: several layers so one failure does not end the story.

Common mistakes

  • Skipping written permission "just for a quick scan".
  • Practising on hostel, office or public targets without authorisation.
  • Collecting tool output without writing the fix.
  • Copying attack steps onto production to "verify". Defenders verify with versions, configs and patches.
  • Publishing screenshots that contain secrets, cookies or internal hostnames.

Recap

  • Evidence, fix, owner, date.
  • Own lab only.
  • Fix > spectacle.

Quick revision cards

Revise this lesson in two minutes. Save the cards on your phone or download them as PNG files. The QR code on each card opens its lesson.

Comparison card: EBS volume vs Instance store. EBS volume: A network disk that lives separately from the EC2. Instance store: A disk physically inside the host computer.
Comparison: EBS volume vs Instance store · Download PNG

More cards: Ravi Sir's Cards.