The driver tries to connect to the database on the primary SQL Server instance by trying to connect to all the IP addresses. When connecting with MultiSubnetFailover=Yes, the client retries TCP connection attempts faster than the operating system's default TCP retransmit intervals. Trusted Mac download Preschool Adventure Island 1.6. Virus-free and 100% clean download. Get Preschool Adventure Island alternative downloads. From sword fighting insults to descending into the lava-filled depths of hell, this game is a masterpiece despite its tired graphics. One of the finest graphic adventures of all time surpassed only by its sequel: Monkey Island 2: LeChuck's revenge. Download The Secret of Monkey Island for Mac. If a macOS installer can't be used on your Mac, the installer will let you know. For example, it might say that it's too old to be opened on this version of macOS, or that your Mac doesn't have enough free storage space for the installation. For disaster recovery on El Capitan and higher, you will need to use Retrospect Backup v17.0.1 or higher. It works with macOS System Integrity Protection, which is on Catalina (10.15) back through El Capitan (10.11). The steps differ from past versions of macOS because of this.
macOS Big Sur elevates the most advanced desktop operating system in the world to a new level of power and beauty. Experience Mac to the fullest with a refined new design. Enjoy the biggest Safari update ever. Discover new features for Maps and Messages. And get even more transparency around your privacy.
Check compatibility
macOS Big Sur is compatible with these computers:
MacBook introduced in 2015 or later
MacBook Air introduced in 2013 or later
MacBook Pro introduced in late 2013 or later
Mac mini introduced in 2014 or later
iMac introduced in 2014 or later
iMac Pro
Mac Pro introduced in 2013 or later
View the complete list of compatible computers.
MacBook Air introduced in 2013 or later
MacBook Pro introduced in late 2013 or later
Mac mini introduced in 2014 or later
iMac introduced in 2014 or later
iMac Pro
Mac Pro introduced in 2013 or later
View the complete list of compatible computers.
If upgrading from macOS Sierra or later, macOS Big Sur requires 35.5GB of available storage to upgrade. If upgrading from an earlier release, macOS Big Sur requires up to 44.5GB of available storage. To upgrade from OS X Mountain Lion, first upgrade to OS X El Capitan, then upgrade to macOS Big Sur.
Make a backup
Before installing any upgrade, it’s a good idea to back up your Mac. Time Machine makes it simple, and other backup methods are also available. Learn how to back up your Mac.
Get connected
It takes time to download and install macOS, so make sure that you have a reliable Internet connection. If you're using a Mac notebook computer, plug it into AC power.
Download macOS Big Sur
If you're using macOS Mojave or later, get macOS Big Sur via Software Update: Choose Apple menu > System Preferences, then click Software Update.
Or use this link to open the macOS Big Sur page on the App Store: Get macOS Big Sur. Then click the Get button or iCloud download icon.
Begin installation
After downloading, the installer opens automatically.
Click Continue and follow the onscreen instructions. You might find it easiest to begin installation in the evening so that it can complete overnight, if needed.
If the installer asks for permission to install a helper tool, enter the administrator name and password that you use to log in to your Mac, then click Add Helper.
Allow installation to complete
Please allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart, show a progress bar, or show a blank screen several times as it installs both macOS and related updates to your Mac firmware.
Stay up to date
After installing macOS Big Sur, you will be notified when updates to macOS Big Sur are available. You can also use Software Update to check for updates: Choose Apple menu > System Preferences, then click Software Update.
Or get macOS Big Sur automatically
If you're using OS X El Capitan v10.11.5 or later and your App Store preferences or Software Update preferences are set to download new updates when available, macOS Big Sur will download conveniently in the background, making it even easier to upgrade. A notification will inform you when macOS Big Sur is ready to be installed. Click Install to get started, or dismiss the notification to install later. When you're ready to install, just open the file named Install macOS Big Sur from your Applications folder.
Learn more
- If the installer shows a list of apps that are not optimized for your Mac, learn about 32-bit app compatibility, then choose whether to proceed with the installation.
- For the strongest security and latest features, upgrade to macOS Big Sur. If you have hardware or software that isn't compatible with Big Sur, you might be able to install an earlier macOS.
- You can also use macOS Recovery to reinstall the macOS you're using now, upgrade to the latest compatible macOS, or install the macOS that came with your Mac.
The ODBC drivers for Linux and macOS support AlwaysOn Availability Groups. For more information about AlwaysOn Availability Groups, see:
You can specify the availability group listener of a given availability group in the connection string. If an ODBC application on Linux or macOS is connected to a database in an availability group that fails over, the original connection is broken and the application must open a new connection to continue work after the failover.
The ODBC drivers on Linux and macOS iterate sequentially through all IP addresses associated with a DNS hostname if you are not connecting to an availability group listener, and multiple IP addresses are associated with the hostname.
If the DNS server's first returned IP address is not connectable, these iterations can be time consuming. When connecting to an availability group listener, the driver attempts to establish connections to all IP addresses in parallel. If a connection attempt succeeds, the driver discards any pending connection attempts.
Note
Because a connection can fail due to an availability group failover, implement connection retry logic; retry a failed connection until it reconnects. Increasing connection timeout and implementing connection retry logic increases the chance of connecting to an availability group.
Connecting With MultiSubnetFailover
Always specify MultiSubnetFailover=Yes when connecting to a SQL Server 2012 (11.x) availability group listener or SQL Server 2012 (11.x) Failover Cluster Instance. MultiSubnetFailover enables faster failover for all Availability Groups and failover cluster instance in SQL Server 2012 (11.x). MultiSubnetFailover also significantly reduces failover time for single and multi-subnet AlwaysOn topologies. During a multisubnet failover, the client attempts connections in parallel. During a subnet failover, the driver aggressively retries the TCP connection.
The MultiSubnetFailover connection property indicates that the application is being deployed in an availability group or Failover Cluster Instance. The driver tries to connect to the database on the primary SQL Server instance by trying to connect to all the IP addresses. When connecting with MultiSubnetFailover=Yes, the client retries TCP connection attempts faster than the operating system's default TCP retransmit intervals. MultiSubnetFailover=Yes enables faster reconnection after failover of either an AlwaysOn Availability Group or an AlwaysOn Failover Cluster Instance. MultiSubnetFailover=Yes applies to both single- and multi-subnet Availability Groups and Failover Cluster Instances.
Use MultiSubnetFailover=Yes when connecting to an availability group listener or Failover Cluster Instance. Otherwise, your application's performance can be negatively affected.
Note the following when connecting to a server in an availability group or Failover Cluster Instance:
- Specify MultiSubnetFailover=Yes to improve performance when connecting to a single subnet or multi-subnet Availability Group.
- Specify the availability group listener of the availability group as the server in your connection string.
- You cannot connect to a SQL Server instance configured with more than 64 IP addresses.
- Both SQL Server Authentication or Kerberos Authentication can be used with MultiSubnetFailover=Yes without affecting the behavior of the application.
- You can increase the value of loginTimeout to accommodate for failover time and reduce the application's connection retry attempts.
- Distributed transactions are not supported.
If read-only routing is not in effect, connecting to a secondary replica location in an availability group fails in the following situations:
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- If the secondary replica location is not configured to accept connections.
- If an application uses ApplicationIntent=ReadWrite and the secondary replica location is configured for read-only access.
A connection fails if a primary replica is configured to reject read-only workloads and the connection string contains ApplicationIntent=ReadOnly.
Specifying Application Intent
The keyword ApplicationIntent can be specified in your connection string. The assignable values are ReadWrite or ReadOnly. The default is ReadWrite.
When ApplicationIntent=ReadOnly, the client requests a read workload when connecting. The server enforces the intent at connection time, and during a USE database statement.
The ApplicationIntent keyword does not work with legacy read-only databases.
Targets of ReadOnly
When a connection chooses ReadOnly, the connection is assigned to any of the following special configurations that might exist for the database:
- A database can allow or disallow read workloads on the targeted Always On database. This choice is controlled by using the ALLOW_CONNECTIONS clause of the PRIMARY_ROLE and SECONDARY_ROLE Transact-SQL statements.
If none of those special targets are available, the regular database is read from.
The ApplicationIntent keyword enables read-only routing.
Read-Only Routing
Read-only routing is a feature that can ensure the availability of a read-only replica of a database. To enable read-only routing, all of the following apply:
- You must connect to an Always On Availability Group availability group listener.
- The ApplicationIntent connection string keyword must be set to ReadOnly.
- The Availability Group must be configured by the database administrator to enable read-only routing.
Multiple connections each using read-only routing might not all connect to the same read-only replica. Changes in database synchronization or changes in the server's routing configuration can result in client connections to different read-only replicas. You can ensure that all read-only requests connect to the same read-only replica. Ensure this sameness by not passing an availability group listener to the Server connection string keyword. Instead, specify the name of the read-only instance.
Read-only routing may take longer than connecting to the primary. The longer wait is because read-only routing first connects to the primary, and then looks for the best available readable secondary. Due to these multiple steps, you should increase your login timeout to at least 30 seconds.
ODBC Syntax
Two ODBC connection string keywords support AlwaysOn Availability Groups:
- ApplicationIntent
- MultiSubnetFailover
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For more information about ODBC connection string keywords, see Using Connection String Keywords with SQL Server Native Client.
The equivalent connection attributes are:
- SQL_COPT_SS_APPLICATION_INTENT
- SQL_COPT_SS_MULTISUBNET_FAILOVER
For more information about ODBC connection attributes, see SQLSetConnectAttr.
An ODBC application that uses AlwaysOn Availability Groups can use one of two functions to make the connection:
Function | Description |
---|---|
SQLConnect Function | SQLConnect supports both ApplicationIntent and MultiSubnetFailover via a data source name (DSN) or connection attribute. |
SQLDriverConnect Function | SQLDriverConnect supports ApplicationIntent and MultiSubnetFailover via DSN, connection string keyword, or connection attribute. |