tailieunhanh - Hướng dẫn học Microsoft SQL Server 2008 part 114

Có gì mới trong cơ sở dữ liệu SQL Server Mirroring? QL Server 2008 cơ sở dữ liệu phản ánh có một số tính năng mới thú vị, một trong số đó được gọi là nén đăng nhập. Như tên cho thấy, tính năng này nén các bản ghi log giao dịch trên máy chủ sản xuất trước khi gửi chúng đến các máy chủ nhân bản. Tính năng này làm giảm băng thông mạng và ứng dụng tăng hiệu năng và thông lượng với chi phí của việc sử dụng CPU tăng lên. | Part VI Enterprise Data Management What s New in SQL Server Database Mirroring SQL Server 2008 database mirroring has some exciting new features one of which is called log compression. As the name suggests this feature compresses the transaction log records on the production server before sending them to the mirror server. This feature reduces network bandwidth and increases application performance and throughput at the cost of increased CPU usage. Another new feature is the capability to automatically repair a page. This means that if the production or mirror server is unable to read a data page due to certain types of errors like 823 824 or 829 then the server that is unable to read the page requests a copy from the other server participating in database mirroring. Upon successful retrieval of the data page the server replaces the unreadable page which resolves the error automatically. This feature is really nice because in order to fix similar errors during a SQL Server 2005 database mirroring session you may have to manually run the DBCC REPAIR_ALLOW_DATA_LOSS option which as the name suggests may result in some data loss. The log compression feature is available in SQL Server 2008 Enterprise Developer and Standard Editions. It is on by default and requires no special configuration or switches. However if the extra CPU usage due to log compression is not desirable in your environment then you can turn off log compression by turning on the trace flag 1462. The automatic page repair feature is not available in SQL Server 2008 Standard Edition. It is available only in SQL Server 2008 Enterprise and Developer Editions. By default it compresses and encrypts the data between the principal and mirror server. It improves the availability of your databases during hardware or software upgrades. It can be used for high database availability and disaster recovery purposes. To achieve high database availability place the principal and mirror SQL Servers in the same .