Bring your own storage
Osiris writes backup data as deduplicated, encrypted chunks (content-defined chunking, SHA-256 hashes, packed into pack files) to storage you choose. The default target needs no extra service at all: local disk on a Docker volume inside the same container, so Osiris runs fully self-contained with just itself plus PostgreSQL and no data ever has to leave your server. Point it at S3-compatible object storage, a mounted NFS share, or SMB instead, and the storage is exactly as good, cheap, or geographically local as whatever you picked, not a markup on top of it.
Why "bring your own" instead of an Osiris cloud
Osiris does not operate a hosted storage service, and there is no plan for one. SeeYour data is your data for the full reasoning. Practically, that means your storage bill is your storage bill: pick a cheap S3-compatible provider, reuse capacity you already pay for, or keep everything on a local disk with nothing metered per gigabyte, per restore, or per API call. More than one storage target per organization is supported: a primary plus a copy is the common pattern for keeping a backup of the backup.
How this compares to a SaaS-hosted backup
Most vendor-hosted Microsoft 365 backup products put your data in the vendor's own cloud by definition (that's what "hosted" means), and several are genuinely good at running that infrastructure; see the vendor comparisons for what each one actually documents about where the bytes live. Osiris's answer is structural rather than a promise: it is not built to operate that cloud in the first place, so there is nothing to trust beyond your own storage choice and Osiris's encryption of what goes into it (see encryption and key handling).
Frequently asked
Where does Osiris store backup data?
Wherever you point it: local disk in the same Docker container by default (no extra service needed to start), or S3-compatible object storage, NFS, or a mounted SMB share instead. Osiris itself does not operate a storage service: there is no "Osiris cloud" your data could end up in.
Can I use more than one storage target?
Yes. More than one target per organization is supported, typically a primary plus a copy, so a single storage failure isn't also a backup failure.
Is the data deduplicated?
Yes. Osiris uses content-defined chunking, so identical content across items and over time is stored once, hashed with SHA-256, and packed into pack files rather than kept as full duplicate copies.