Veeam backups for Microsoft 365 with 5,000+ users

The challenge

The protagonist of this case is a Veeam-focused integrator that operates backup for several corporate clients. One of them has a Microsoft 365 tenant with more than 5,000 users, and although Microsoft replicates data for availability, it does not protect it against accidental deletions, departing employees or ransomware. The responsibility for keeping a recoverable, independent copy falls on the integrator, which already used Veeam Backup for Microsoft 365 to cover Exchange Online, SharePoint, OneDrive and Teams.

The problem wasn't Veeam, but where to keep the copies. Offloading M365 to object storage ran into two recurring obstacles:

• A bill impossible to forecast. Microsoft 365 backups are not a handful of large files: they are millions of small objects (individual emails, SharePoint and OneDrive items, Teams messages). With a provider that charges for every PUT, GET, LIST and sometimes even DELETE operation, the tens of millions of requests Veeam generates while backing up and retaining that tenant turned the cost into a monthly guessing game.
• Performance on granular restores. The real value of M365 backup lies in recovering a specific mailbox, a SharePoint folder or the OneDrive of someone who has left. On slow storage, scanning catalogs with millions of small objects to locate and restore individual items becomes painful.

The integrator needed an external destination, natively compatible with Veeam, with a cost that could be calculated in advance and enough performance to keep restores from dragging on.

The solution with OtterStorage

OtterStorage plugs into Veeam Backup for Microsoft 365 as just another S3-compatible object storage: no proprietary agents or gateways. The integrator added the destination pointing to the https://es-mad-1.s3.otterstorage.io endpoint, in the eu-mad region, and chose the SSD pool precisely because of the M365 workload profile.

The setup they put in place:

• A dedicated bucket per client. They created an exclusive bucket for this tenant (for example veeam-m365-cliente) with its own folder, so this client's copies stay separate from the rest of their portfolio.
• Isolated access keys. Each bucket has its own access key + secret key, so the credentials living in the Veeam Backup for Microsoft 365 console only grant access to that repository and to no other data in the organization.
• SSD pool as the backup repository. When defining the backup repository on OtterStorage's object storage, they chose SSD so that the catalog and the granular restores of Exchange, SharePoint, OneDrive and Teams respond with the latency a volume of 5,000+ users demands.
• Immutability when required. For buckets subject to retention, OtterStorage lets you back the protection with Object Lock (OtterVault) and apply bucket-level Legal Hold, so that not even an attacker with the credentials can delete or overwrite the copies during the set period.

The economic piece that makes it viable is the pricing model: OtterStorage does not charge for requests (PUT/GET/LIST) or for deletes (DELETE). With M365 and its millions of small objects, this stops being a detail and becomes the difference between an estimable cost and a surprise. The integrator pays for the TB of the SSD pool (16 €/TB per month) and nothing more, with no lock-in and a 15% discount on an annual plan.

If you want to reproduce this architecture, the exact configuration steps are in the S3 repository for Veeam solution, and the detail of bucket isolation in per-bucket access keys.

Results

• 5,000+ Microsoft 365 users protected with Exchange Online, SharePoint, OneDrive and Teams backed up to an external destination independent of the tenant.
• Predictable, low cost: 0 € per request and 0 € per delete, despite the millions of small objects M365 generates; the bill depends only on the TB used in the SSD pool.
• Faster backups and granular restores thanks to the performance of the SSD pool, key to scanning huge catalogs and recovering individual items.
• Total per-client isolation through independent buckets and dedicated access keys, with the option of immutability (Object Lock) and bucket-level Legal Hold when retention requirements apply.
• Native compatibility with Veeam Backup for Microsoft 365: integration as S3 Compatible, with no middleware or in-house infrastructure to maintain.

More backup scenarios in backup solutions and a full pricing breakdown in pricing.