Chapter 13: Amazon EBS (Elastic Block Store)
Interview Questions
- 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, thensudo xfs_growfs -d /(XFS) orsudo resize2fs /dev/nvme0n1p1(ext4); verify withdf -hT. - Q5. Why do we use UUID and
nofailin /etc/fstab? - NVMe device names can change between boots; the UUID is stable.
nofaillets 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.