Content database size
200 GB per content database
We strongly recommended limiting the size of content databases to 200 GB to help ensure system performance.
Content database sizes up to 1 terabyte are supported only for large, single-site repositories and archives with non-collaborative I/O and usage patterns, such as Records Centers. Larger database sizes are supported for these scenarios because their I/O patterns and typical data structure formats have been designed for, and tested at, larger scales. For more information about large-scale document repositories, see "Estimate Performance and Capacity Requirements for Large Scale Document Repositories", available from Performance and capacity test results and recommendations (SharePoint Server 2010), and “Typical large-scale content management scenarios”, available from Enterprise content storage planning (SharePoint Server 2010).
A site collection should not exceed 100 GB unless it is the only site collection in the database.
Site collections per content database
We strongly recommended limiting the number of site collections in a content database to 2,000. However, up to 5,000 site collections in a database are supported.
These limits relate to speed of upgrade. The larger the number of site collections in a database, the slower the upgrade.
The limit on the number of site collections in a database is subordinate to the limit on the size of a content database that has more than one site collection (200 GB). Therefore, as the number of site collections in a database increases, the average size of the site collections it contains must decrease.
Exceeding the 2,000 site collection limit puts you at risk of longer downtimes during upgrades. If you plan to exceed 2,000 site collections, we recommend that you have a clear upgrade strategy, and obtain additional hardware to speed up upgrades and software updates that affect databases.
To set the warning level for the number of sites in a content database, use the Windows PowerShell cmdlet Set-SPContentDatabase with the -WarningSiteCount parameter. For more information, see Set-SPContentDatabase.
Remote BLOB Storage (RBS) storage subsystem on Network Attached Storage (NAS)
Time to first byte of any response from the NAS cannot exceed 20 milliseconds
When SharePoint Server 2010 is configured to use RBS, and the BLOBs reside on NAS storage, consider the following boundary.
From the time that SharePoint Server 2010 requests a BLOB, until it receives the first byte from the NAS, no more than 20 milliseconds can pass.