Wednesday, November 7, 2012

Sharepoint 2010 Capacity Management - I

Limits and boundaries

The below table gives a detailed information on the guidelines for acceptable performance for objects in SharePoint. In this section I am focusing on the Web applications, Web server and application servers, Content databases and Site collections. Acceptable performance means that the system as tested can support that number of objects, but that the number cannot be exceeded without some decrease in performance or a reduction in the value of related limits.

• Boundaries: Static limits that cannot be exceeded by design

• Thresholds: Configurable limits that can be exceeded to accommodate specific requirements

• Supported limits: Configurable limits that have been set by default to a tested value

Limits by hierarchy

This section provides limits sorted by the logical hierarchy of a SharePoint Server 2010 farm.

Web application limits

The following table lists the recommended guidelines for Web applications.

Maximum value
Limit type
Content database
300 per Web application
With 300 content databases per Web application, end user operations such as opening the site or site collections are not affected. But administrative operations such as creating a new site collection will experience decrease in performance. We recommend that you use Windows PowerShell to manage the Web application when a large number of content databases are present, because the management interface becomes slow and difficult to navigate.
5 per Web application
The number of zones defined for a farm is hard-coded to 5. Zones include Default, Intranet, Extranet, Internet, and custom.
Managed path
20 per Web application
Managed paths are cached on the Web server, and CPU resources are used to process incoming requests against the managed path list.
Exceeding 20 managed paths per Web application adds more load to the Web server for each request.
If you plan to exceed twenty managed paths in a given Web application, we recommend that you test for acceptable system performance.
Solution cache size
300 MB per Web application
The solution cache allows the InfoPath Forms service to hold solutions in cache in order to speed up retrieval of the solutions. If the cache size is exceeded, solutions are retrieved from disk, which may slow down response times. You can configure the size of the solution cache by using the Windows PowerShell cmdlet Set-SPInfoPathFormsService.
Site collection
250,000 per Web application
The maximum recommended number of site collections per Web application is 250,000.
Note that this limit is affected by other factors that might reduce the effective number of site collections that can be supported by a given Web application. Care must be exercised to avoid exceeding supported limits when a container object, such as a content database, contains a large number of other objects.
For example, in a farm that contains a large number of Web applications, the total number of site collections might reach a number that cannot effectively be supported by farm resources. This can be true even when both the number of Web applications per farm and the number of site collections per Web application fall within their supported limits.
Similarly, if a farm contains a smaller total number of content databases, each of which contains a large number of site collections, farm performance might be adversely affected long before the supported limit for the number of site collections is reached.
The following case illustrates this point.
Farm A contains a Web application that has 200 content databases, a supported configuration. If each of these content databases contains 200 site collections, the total number of site collections in the Web application will be 40,000, which falls within supported limits. However, if each content database contains 2,000 site collections, even though this number is supported for a content database, the total number of site collections in the Web application will be 400,000, which exceeds the limit for the number of site collections per Web application.

Web server and application server limits

The following table lists the recommended guidelines for Web servers on the farm. 

Maximum value
Limit type
Application pools
10 per Web server
The maximum number is determined by hardware capabilities.
This limit is dependent largely upon:
·         The amount of RAM allocated to the Web servers
·         The workload that the farm is serving, that is, the user base and the usage characteristics (a single highly active application pools can reach 10 GB or more)

Content database limits

The following table lists the recommended guidelines for content databases. 

Maximum value
Limit type
Content database size (general usage scenarios)
200 GB per content database
We strongly recommended limiting the size of content databases to 200 GB, except when the circumstances in the following rows in this table apply.
If you are using Remote BLOB Storage (RBS), the total volume of remote BLOB storage and metadata in the content database must not exceed this limit.
Content database size (all usage scenarios)
4 TB per content database
Content databases of up to 4 TB are supported when the following requirements are met:
·         Disk sub-system performance of 0.25 IOPs per GB. 2 IIOPs per GB is recommended for optimal performance.
·         You must have developed plans for high availability, disaster recovery, future capacity, and performance testing.
You should also carefully consider the following factors:
·         Requirements for backup and restore may not be met by the native SharePoint Server 2010 backup for content databases larger than 200 GB. It is recommended to evaluate and test SharePoint Server 2010 backup and alternative backup solutions to determine the best solution for your specific environment.
·         It is strongly recommended to have proactive skilled administrator management of the SharePoint Server 2010 and SQL Server installations.
·         The complexity of customizations and configurations on SharePoint Server 2010 may necessitate refactoring (or splitting) of data into multiple content databases. Seek advice from a skilled professional architect and perform testing to determine the optimum content database size for your implementation. Examples of complexity may include custom code deployments, use of more than 20 columns in property promotion, or features listed as not to be used in the over 4 TB section below.
·         Refactoring of site collections allows for scale out of a SharePoint Server 2010 implementation across multiple content databases. This permits SharePoint Server 2010 implementations to scale indefinitely. This refactoring will be easier and faster when content databases are less than 200 GB.
It is suggested that for ease of backup and restore that individual site collections within a content database be limited to 100 GB.
Content database size (document archive scenario)
No explicit content database limit
Content databases with no explicit size limit for use in document archive scenarios are supported when the following requirements are met:
·         You must meet all requirements from the “Content database size (all usage scenarios)” limit earlier in this table, and you should ensure that you have carefully considered all the factors discussed in the Notes field of that limit.
·         SharePoint Server 2010 sites must be based on Document Center or Records Center site templates.
·         Less than 5% of the content in the content database is accessed each month on average, and less than 1% of content is modified or written each month on average.
·         Do not use alerts, workflows, link fix-ups, or item level security on any SharePoint Server 2010 objects in the content database.
Content database items
60 million items including documents and list items
The largest number of items per content database that has been tested on SharePoint Server 2010 is 60 million items, including documents and list items. If you plan to store more than 60 million items in SharePoint Server 2010, you must deploy multiple content databases.
Site collections per content database
2,000 recommended
5,000 maximum
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.
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.

Site collection limits

The following table lists the recommended guidelines for site collections. 

Maximum value
Limit type
Web site
250,000 per site collection
The maximum recommended number of sites and subsites is 250,000 sites.
You can create a very large total number of Web sites by nesting subsites. For example, in a shallow hierarchy with 100 sites, each with 1,000 subsites, you would have a total of 100,000 Web sites. Or a deep hierarchy with 100 sites, each with 10 subsite levels would also contain a total of 100,000 Web sites.
Note: Deleting or creating a site or subsite can significantly affect a site’s availability. Access to the site and subsites will be limited while the site is being deleted. Attempting to create many subsites at the same time may also fail.
Site collection size
Maximum size of the content database
A site collection can be as large as the content database size limit for the applicable usage scenario. In general, we strongly recommend limiting the size of site collections to 100 GB for the following reasons:
·         Certain site collection actions, such as site collection backup/restore or the Windows PowerShell cmdlet Move-SPSite, cause large Microsoft SQL Server operations which can affect performance or fail if other site collections are active in the same database.
·         SharePoint site collection backup and restore is only supported for a maximum site collection size of 100 GB. For larger site collections, the entire content database must be backed up. If multiple site collections larger than 100 GB are contained in a single content database, backup and restore operations can take a long time and are at risk of failure.

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