Why restore tests matter more than backups
A backup that has never been restored is a claim, not a fact. The only way to actually know a backup works is to read it back and check. A green "backup completed" status proves the write succeeded, nothing about whether the data comes back correctly later, which is the only reason the backup exists at all.
What tends to go wrong, silently
Encryption keys drift out of sync with what was used to write a chunk. Storage silently corrupts a block that isn't read again for months. A format change quietly breaks compatibility with older archives. None of these show up in a backup job's own success status. They only show up when someone actually tries to restore, which is precisely the moment nobody wants to discover a problem for the first time.
What Osiris does about it
A backup without a verified restore is shown, in the product, as not done, not quietly rounded up to success. Today that's enforced by a weekly sampled recovery-readiness check per mailbox and OneDrive: an actual restore of a sample, compared back, with any failure surfaced on that mailbox's own status. Full, per-item restore verification for everything backed up (not a sample) is in active development; seethe verification feature page for exact current status, andhow Osiris is built for the release checklist every version has to pass, which already includes a full backup-and-restore run with a byte-for-byte hash comparison before any tag ships, plus proving a restore works from the standalone tool with no Osiris server running at all.
Frequently asked
Why is an untested backup not actually a backup?
Because "backup completed successfully" only proves the write succeeded. It says nothing about whether the data can actually be read back correctly later, which is the entire point of having a backup in the first place. A corrupted chunk, a broken encryption key, or a subtle format bug can all sit silently inside a backup that reports green for months, discovered only at the worst possible moment: during an actual emergency restore.
What does Osiris check today, versus what's still coming?
Today: a weekly sampled recovery-readiness check per mailbox and OneDrive, an actual restore of a sample, compared back, shown honestly as a sample. In development: full, complete-coverage verification of every backed-up item, restoring into a separate target automatically rather than sampling. See the features page on verification for the current, exact status.