Microsoft 365 storage economics
The questions admins actually ask about SharePoint and OneDrive storage costs, answered with Microsoft's own numbers and sources.
SharePoint went read-only after you ran over storage: "Confirm purchase", what actually frees space, and what Learn does not tell you
Confirm purchase lifts read-only for up to 14 days and works once in 365 days. The three ways out, what frees space fastest (Archive, recycle bins, versions, and why Preservation Hold blocks deletion), and the day count Learn gives Education tenants but not commercial ones.
OneDrive above 5 TB: what goes read-only from November 2026, and what the $0.20 meter costs
Legacy OneDrive increases above 5 TB are removed for E3 and E5 users between November 2026 and February 2027, and a drive over its licensed quota goes read-only. Why deleting files often does not help (versions, recycle bins, Preservation Hold), how to list the accounts, and capacity packs against the $0.20 pay-as-you-go meter, worked through.
SharePoint "Plan 2" is not unlimited: how the tenant pool is really sized, which licences add to it, and what eats it
1 TB plus 10 GB per eligible licence, in binary gigabytes, and "Plan 2" adds nothing. Which SKUs count and which add zero (F3), what draws on the pool and what doesn't, what happens at the line, and the three ways out with Learn's prices.
Version history trimming: what it actually reclaims, and what retention quietly blocks
Changing a version limit reclaims nothing until files are edited; only a trim job frees existing versions, and only where no retention policy, hold or record label covers them. The three deletion paths, the automatic algorithm, the what-if report, the cmdlets, and how to get the real number first.
Where your Microsoft 365 storage actually goes: a read-only audit in four layers
The admin center bar is one number; the renewal needs four. Pool position, top sites, then live files vs versions vs recycle bins vs Preservation Hold copies, measured with read-only commands and priced against the $0.20 and $0.05 meters.
OneDrive for Business Plan 2 is being retired: what "unlimited" actually was, and what to move where before January 2027
No renewals after January 2027, end of service December 2029. The 1 → 5 → 25 TB ladder (closing above 5 TB from November 2026), the read-only trap on licence swap, and a four-bucket triage against the real meters ($0.20 active, $0.05 archive).
Unlicensed OneDrive billing: what Microsoft actually charges, and the decision you must make before day 93
The archive meter is tenant-wide: one reactivation turns on $0.05/GB/month for every archived unlicensed OneDrive. The timeline, the two meters, the retention-hold trap, and the three options per account. Updated for the 1 July 2026 rule: cumulative 365-day unpaid clock, day-275 eDiscovery cutoff, and 1 July 2027 as the first deletion-risk date for accounts that were already unlicensed.