Deployment Best Practices for Large Microsoft 365 Tenants

Protecting a Microsoft 365 tenant with more than 1,000 users requires a different approach from backing up a small business environment. Large tenants contain thousands of Exchange mailboxes, OneDrive accounts, SharePoint sites, Teams channels, shared mailboxes, and Microsoft 365 Groups. Without careful planning, initial backups can take longer than expected, Microsoft throttling can interrupt progress, and storage requirements can grow rapidly.

Enterprise deployments demonstrate that Synology can support large environments successfully. Idea Bank used Synology Active Backup for Microsoft 365 to protect more than 1,250 accounts and hundreds of SharePoint sites on each of two RackStation systems. Corin protected 2,463 Microsoft 365 accounts, while King’s Baptist Grammar School reported using the platform for more than 1,000 cloud users.

The following practices help organisations deploy Synology Microsoft 365 backup efficiently at enterprise scale.

Assess the Tenant Before Choosing Hardware

Hardware selection should begin with a detailed tenant assessment rather than user count alone.

Administrators should review:

Total Microsoft 365 data volume
Average mailbox size
OneDrive and SharePoint consumption
Number of Teams and Microsoft 365 Groups
Daily data-change rate
Required retention period
Expected user growth

Two organisations with 1,000 users may have very different requirements. A school with small student mailboxes may consume less storage than a design company with large OneDrive and SharePoint repositories.

Choose Hardware with Sufficient Resources

Large tenants require adequate processing power, memory, storage throughput, and network bandwidth.

For enterprise deployments, organisations should prioritise:

A supported x86-64 Synology NAS
Btrfs storage volumes
At least 16 GB of memory
Enterprise or datacentre-grade drives
10GbE connectivity
Sufficient free capacity for growth
Expansion support where required

Synology’s technical specifications indicate that systems with at least 16 GB of memory can support higher backup concurrency. Active Backup for Microsoft 365 also uses single instancing and block-level deduplication where supported to improve storage efficiency.

Separate Workloads into Manageable Tasks

Backing up every service and account through one large task may make troubleshooting and performance monitoring more difficult.

Large organisations should consider separating tasks by:

Exchange Online
OneDrive
SharePoint Online
Microsoft Teams
Departments
User groups
Geographic locations

For example, Exchange mailboxes may run in one task while OneDrive and SharePoint data are assigned to separate schedules. This makes it easier to identify which workload is experiencing errors or throttling.

Task segmentation also allows administrators to prioritise executives, finance teams, critical departments, or compliance-sensitive SharePoint sites.

Plan for Microsoft 365 Throttling

Backup speed is not controlled entirely by the Synology NAS. Microsoft applies global and service-specific throttling limits to protect Microsoft 365 availability. These limits may apply per application, tenant, service, or request type.

Throttling may appear as:

Slower transfer speeds
Temporary pauses
Failed requests
Longer initial backup windows
HTTP 429 or 503 responses

Synology recommends using a custom Azure application to reduce API throttling in Active Backup for Microsoft 365. Microsoft also advises applications to respect retry instructions and pause additional requests when throttling responses occur. Continuing to send requests can extend the throttling period.

Schedule Initial Backups Strategically

The first backup transfers the entire protected dataset and will usually take much longer than later incremental backups.

Initial tasks should be scheduled during:

Evenings
Weekends
School holidays
Maintenance windows
Other low-activity periods

Rather than starting all workloads simultaneously, administrators can introduce Exchange, OneDrive, SharePoint, and Teams tasks in phases. Microsoft notes that processing all content in a single task or operating during peak usage can increase the likelihood of SharePoint and OneDrive throttling.

Monitor Storage and Performance

During deployment, administrators should monitor:

CPU and memory utilisation
Disk latency and throughput
Network bandwidth
Backup task progress
Microsoft throttling messages
Storage consumption
Failed or skipped objects

If disk utilisation remains consistently high, the system may require faster drives, additional memory, improved RAID design, or a more capable Synology platform.

Storage forecasts should also include retention growth and temporary space for package operations, indexing, and future account expansion.

Use Deduplication to Improve Efficiency

Large Microsoft 365 environments often contain repeated files and attachments.

Synology reduces duplication through single instancing and block-level deduplication on supported Btrfs volumes. In one education deployment, Tampere Vocational College reported that deduplication reduced its first backup by approximately 7 TB, delivering a 46% storage saving.

Actual savings depend on file similarity, retention settings, and workload composition.

Validate Recovery Before Production Sign-Off

A successful backup does not guarantee a successful recovery.

Before completing the deployment, organisations should test:

Individual email restoration
OneDrive file recovery
SharePoint restoration
Microsoft Teams recovery
User permissions
Self-service portal access
Recovery time objectives

Synology’s recovery portal can allow authorised users to restore their own data, reducing routine IT support requests. Deploy large M365 backups with Synology best practices.

About Epis Technology

Epis Technology helps organisations design, deploy, and optimise large Synology Microsoft 365 backup environments through tenant assessments, hardware selection, storage architecture, task segmentation, throttling management, capacity planning, recovery testing, and ongoing managed support. With deep Synology expertise, Epis Technology helps businesses protect tenants with thousands of users while maintaining reliable performance, scalable storage, and efficient recovery operations.

Deployment Best Practices for Large Microsoft 365 Tenants