??? The Recover Interval instance setting has been reached (this indicates how often
checkpoints occur).
??? You make a database backup (when in Simple Recovery mode).
??? The database file structure is altered (when in Simple Recovery mode).
??? The database engine is stopped.
The normal process for writing data to disk occurs automatically, as shown in
Figure 2-1. However, it isn??™t written directly to an .mdf or .ndf file. All data first goes to the
transaction log.
Normal write operations act accordingly. Although this is simplified greatly, write
operations follow these basic steps:
1. The user issues some sort of INSERT, UPDATE, or DELETE statement.
2. The data is immediately written to the internal log cache.
3. The log cache updates the physical transaction log file (.ldf) and makes changes
in the data buffer cache.
4. The data buffer is eventually cleared of all ???dirty??? buffers, and the data files (.mdf
or .ndf) are updated.
CHAPTER 2 n MAKING DATABASE BACKUPS 15
Figure 2-1. The ongoing process of writing data to the disk in SQL Server
When a database backup occurs, only the actual data and transaction log files are
written to disk.
Pages:
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78