Proxy Servers
Within a Veeam Backup for Microsoft 365 environment, the Proxy servers are executing the actual data processing. The number of Objects, and the size of the data within these Objects, is determining the required number of resources needed to process the backups in a curtain amount of time.
However, the actual backup time is also defined by the performance the source Microsoft 365 tenant can deliver. To ensure a proper end-user experience, Microsoft is actively managing the assigned resources for each Microsoft 365 tenant based on the amount of user licenses assigned and throttles when needed. This mechanism results in a specific number of assigned API calls which are available within your Microsoft 365 tenant for services like backup. More information can be found here: M365 Throttling
When sizing Veeam Backup for Microsoft 365 Proxies, two essential Veeam Backup for Microsoft 365 parameters need consideration:
- Number of Objects to Protect
- Amount of data to be processed
When a backup job is executed by a proxy, this proxy will start multiple threads to process the data. A thread can process one object in terms of a SharePoint Site, a OneDrive, a Mailbox or a Teams.
Size for Objects
Refer to the Configuration Maximums to determine the necessary number of proxies and the capacity for handling various object types, such as Mail, Archive, Site, OneDrive, and Teams. Bases on these configuration maximums and experience from the field we can say a recommended proxy config with 8 CPU Cores and 32GB ram should be able to handle 20.000 objects.
Size for amount of data
The sizing of Veeam Backup for Microsoft 365 Proxies depends also on the amount of data which needs to be processed during the initial full backup. Each proxy will be capable of a curtain amount of throughput. Below information can be used as a best-case scenario/reference for sizing the required number of proxies.
- Exchange data: 8 MB/s per proxy core (64 MB/s per proxy with 8 cores)
- SharePoint data: 5 MB/s per proxy core (40 MB/s per proxy with 8 cores)
Do not forget to keep the desired backup window in mind when calculating the total required throughput. Veeam Backup for Microsoft 365 is using a Forever-Incremental backup format. This means that we’ll make one initial full backup of the source data and continue with incremental backups onwards. Processing the initial full backup can require a longer processing window than preferred based on the limits of the Microsoft 365 tenant. For SharePoint, we use/apply rate limits. Microsoft Rate Limit depends on the tenant quota. Additionally, there’s Microsoft Egress limit – 400 GB per hour. More information about throttling can be found here: M365 Throttling
Considerations:
When defining the required amount of proxies and type/models take the following considerations into account:
- Multiple lower-size proxies in a pool over time should be more efficient than a single fat proxy. For instance, two 4 CPU/16 GB RAM proxies will be more efficient than an 8 CPU / 32 GB RAM proxy.
- Performance comparisons showed that Linux proxies within a pool operate slightly more efficient than Windows based proxies
- When you plan to run Veeam Backup for Microsoft 365 within Microsoft Azure: Choose an appropriate machine type (F or D-Type) for best performance. Machine type B is not recommended due to CPU-limitations.
CPU to Memory ratio
The CPU : RAM ratio should be at least 1 : 4 for Proxies (4GB of RAM per 1 CPU core). Depending on the load this might need to be increased up to a maximum 1 : 8 ratio. Because every source environment has different amount and sizes of items to be processed, this requirement can variate.
A suggestion is to start with 4 cores and 16GB RAM per proxy server and scale up to a maximum of 16 ocres and 64GB RAM. But again, multiple lower-size proxies in a pool over time should be more efficient than a single fat proxy.