Storage

Cards

1. A file service sends 500 TB a month to users. If data transfer out costs $0.05 per GB, what is the monthly egress bill? easy Estimate
2. Why do HLS video segments cache so well on a CDN? easy Multiple choice
3. A paste or file service stores both small facts (owner, expiry, size) and large bodies. Where does each go, and why? easy Flashcard
4. Large files go to S3 with _____: the file is sent in parts that upload in _____, and a failed part is retried on its own. easy Fill in the blank
5. Where do you store user-uploaded photos and videos, and why not on the app servers' disks? easy Flashcard
6. Object storage offers hot, infrequent-access and archive classes. What do the cheaper ones cost you? easy Flashcard
7. Clients upload straight to object storage with pre-signed URLs. How should the backend learn that an upload finished? easy Multiple choice
8. Where should a database server keep its data files? medium Multiple choice
9. How can a file sync service avoid storing the same bytes twice? medium Flashcard
10. Replication protects against lost disks, but not against a buggy job deleting objects, because the delete is replicated too. Protect against that with object _____. medium Fill in the blank
11. You store 1 PB of data with 10 + 4 erasure coding (each 10 data pieces get 4 parity pieces). How much raw disk do you need, before headroom? medium Estimate
12. How much storage does one hour of video at 5 Mbit/s take? medium Estimate
13. How do pre-signed URLs let clients upload large files without the bytes passing through your servers? medium Flashcard
14. Erasure coding versus 3× replication for durable storage: what do you trade? hard Flashcard