Storage Math: RAID Capacity, Backup Windows & Retention Costs

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Compare six candidate disk arrays for Kestrel Post, a fictional video post-production studio: raw TB, usable TB per RAID level from a lookup table, storage efficiency and the TiB your operating system will actually show.
• Turn a spec-sheet MTBF into an annual failure rate, estimate how likely a drive failure is in Kestrel Post's 12-drive array each year, how long a rebuild takes and how likely a read error is during a single-parity rebuild.
• Check whether each of Kestrel Post's six full backups fits the 8-hour night window: effective throughput from the slowest link, hours per job, a Yes/No check and the throughput each job would need.
• Compare a week of daily full backups with a Sunday full plus incrementals or differentials for Kestrel Post's 20 TB file share, and measure how much backup storage incrementals save.
• Size the backup storage for Kestrel Post's grandfather-father-son retention policy: size per copy by type, storage per tier, the total and the retention multiplier.
• Turn the 468.4 TB of logical backup data from the GFS lab into physical TB per data type and find Kestrel Post's true overall data-reduction ratio.
• Compare five years of keeping Kestrel Post's 240 physical TB of backups in a cloud archive tier with an on-premises tape library, and express both as cost per TB-month.
• Test whether Kestrel Post's backup setup can meet the recovery targets the business asked for: achieved recovery time per system, a both-targets check, a count and a bar chart of target vs achieved RTO.