How do you control storage costs as data grows over time?
What they are really testing: Whether you know storage tiering by access frequency, lifecycle policies to move/expire data automatically, and cleaning up orphaned storage, rather than letting storage grow unbounded.
A real interview question
How do you control storage costs as data grows over time?
What most people say
drag me
“I would delete old data that is not needed anymore.”
Deleting helps but is manual and crude. The systematic answer is tiering by access frequency with automated lifecycle policies, plus cleaning orphaned storage, and being aware of retrieval costs on cold tiers. Just "delete old data" misses the mechanism.
The follow-ups they ask next
What is the trade-off of moving data to a cold/archive tier?
Much cheaper storage, but retrieval costs money and is slower (sometimes hours). Only tier data there if it is genuinely rarely accessed; otherwise retrieval fees can exceed what you saved on storage.
What orphaned storage commonly racks up cost?
Unattached volumes from deleted instances, old snapshots/backups beyond retention, incomplete multipart uploads, and forgotten buckets/datasets. They bill monthly with no value, so sweep for them regularly.
What the interviewer is listening for
- Tiers by access frequency
- Automates with lifecycle policies
- Cleans orphans + knows retrieval-cost trade-off
What sinks the answer
- Only "delete old data"
- No lifecycle automation
- Unaware of cold-tier retrieval cost
If you genuinely do not know
Say this instead of freezing. Reasoning out loud from what you do know beats silence every single time, and a good interviewer is listening for exactly that.
“Manage storage by [tiering on access frequency: hot, infrequent-access, archive/cold, each cheaper per GB]. Automate with [lifecycle policies that transition to colder tiers as data ages and expire it after retention]. Clean up [orphans: unattached volumes, old snapshots, incomplete uploads]. Mind that [cold tiers charge for retrieval and are slower], so tier by genuine access patterns.”
Keep going with cost
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What does elasticity mean in the cloud, and how does pay-as-you-go change the cost model compared to running your own servers?
Foundation
What are the main things that drive a cloud bill?
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Why is data egress (data transfer) often a hidden cost, and how do you reduce it?
Junior
What is right-sizing, and why is over-provisioning the most common source of cloud waste?
Junior
Compare on-demand, committed/reserved, and spot/preemptible pricing. How do you mix them?
Junior
Why is resource tagging important for cost management?
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