SQL SERVER Administration Optimizations with PeopleSoft Application

Dedicated Administrator Connection (DAC)
SQL Server provides a special diagnostic connection for administrators when standard connections to the server are not possible. This diagnostic connection allows an administrator to access SQL Server to execute diagnostic queries and troubleshoot problems even when SQL Server is not responding to standard connection requests. The DAC is available through the sqlcmd utility and SQL Server Management Studio.

To connect to a server using the DAC

1. In SQL Server Management Studio, with no other DACs open, on the toolbar, click Database Engine Query.
2. In the Connect to Database Engine dialog box, in the Server name box, type ADMIN: followed by the name of the server instance. For example, to connect to a server instance named HRSrvr\HRProd, type ADMIN: HRSrvr\HRProd.
3. Complete the Authentication section, providing credentials for a member of the sysadmin group, and then click Connect.


I/O Optimizations

Instant File Initialization
For large PeopleSoft installations, the newly introduced SQL Server feature, instant file initialization, can be leveraged to avoid long waits when the data file expands.

Data and log files are first initialized by filling the files with zeros when you perform one of the following operations:

• Create a database.
• Add files, log or data, to an existing database.
• Increase the size of an existing file (including autogrow operations).
• Restore a database or filegroup.

The initialization of the data or log file with zeros usually leads to wait time and blackouts, if a large expansion is required.

In SQL Server, data files can be initialized instantaneously for fast execution of the previously mentioned file operations. Instant file initialization reclaims used disk space without filling that space with zeros. Instead, disk content is overwritten as new data is written to the files. Log files cannot be initialized instantaneously.

Instant file initialization is available only if the SQL Server (MSSQLSERVER) service account has been granted SE_MANAGE_VOLUME_NAME. Members of the Windows Administrator group have this right and can grant it to other users by adding them to the Perform Volume Maintenance Tasks security policy.
The SE_MANAGE_VOLUME_NAME privilege is granted by default and no specific action is required to use this feature.

Security Considerations
Because the deleted disk content is overwritten only as new data is written to the files, the deleted content might be accessed by an unauthorized principal. While the database file is attached to the instance of SQL Server, this information disclosure threat is reduced by the discretionary access control list (DACL) on the file. This DACL allows file access only to the SQL Server service account and the local administrator. However, when the file is detached, it may be accessed by a user or service that does not have SE_MANAGE_VOLUME_NAME. A similar threat exists when the database is backed up. The deleted content can become available to an unauthorized user or service if the backup file is not protected with an appropriate DACL.

If the potential for disclosing deleted content is a concern, you should do one or both of the following:

• Always make sure that any detached data files and backup files have restrictive DACLs.
• Disable instant file initialization for the instance of SQL Server by revoking SE_MANAGE_VOLUME_NAME from the SQL Server service account.

Note. Disabling instant file initialization only affects files that are created or increased in size after the user right is revoked.

For PeopleSoft applications, instant file initialization is recommended from a performance perspective. However, evaluate the performance gain against the possible security risk. If the security policy does not allow for this possible risk, do not use instant file initialization. You can disable it by revoking SE_MANAGE_VOLUME_NAME from the SQL Server service account.

Long I/O Requests
In SQL Server, the buffer manager reports on any I/O request that has been outstanding for at least 15 seconds. This helps the system administrator distinguish between SQL Server problems and I/O subsystem problems. Error message 833 is reported and appears in the SQL Server error log as follows:

SQL Server has encountered %d occurrence(s) of I/O requests taking longer than %d
seconds to complete on file [%ls] in database [%ls] (%d). The OS file handle is 0x%p.
The offset of the latest long I/O is: %#016I64x.

A long I/O may be either a read or a write; it is not currently indicated in the message. Long I/O messages are warnings, not errors.

Note. Long I/O warning messages are related to functional disk errors only. For performance tuning of I/O issues, use the I/O related dynamic management views and System Monitor counters.

For PeopleSoft applications, I/O error message 833 can be very useful from a reactive I/O maintenance and monitoring perspective. It is recommended that you monitor the SQL Server error log for these messages. However, for I/O performance tuning, it is recommended that you use the I/O-related dynamic management views and System Monitor counters.