Cisco Cisco Broadband Access Center for Cable 4.1
C H A P T E R
7-1
Cisco Broadband Access Center for Cable Administrator’s Guide
OL-2445-02
7
Database Management
This chapter contains information on RDU database management and maintenance. The RDU database
is the Broadband Access Center for Cable (BAC) central database. As with any database, it is essential
that you, as the administrator, understand and be familiar with database backup and recovery procedures.
is the Broadband Access Center for Cable (BAC) central database. As with any database, it is essential
that you, as the administrator, understand and be familiar with database backup and recovery procedures.
Understanding Failure Resiliency
The RDU database uses a technique known as write-ahead logging to protect against database corruption
that could result from, such unforeseen problems as an application crash, system failure, or power
outage.
that could result from, such unforeseen problems as an application crash, system failure, or power
outage.
Write-ahead logging involves writing a description of any database change to a log file prior to writing
the change into the database files. Doing so allows the repair of any incomplete database writes that can
result from system failures.
the change into the database files. Doing so allows the repair of any incomplete database writes that can
result from system failures.
The RDU server performs an automatic recovery each time it is started. During this recovery process,
the log files are used to synchronize the data with the database files. Database changes that were written
into the log, but not into the database, are written into the database during this automatic recovery.
the log files are used to synchronize the data with the database files. Database changes that were written
into the log, but not into the database, are written into the database during this automatic recovery.
In this way, write-ahead logging virtually guarantees that the database does not become corrupted when
the RDU server crashes because the database is automatically repaired when the RDU server is restarted.
the RDU server crashes because the database is automatically repaired when the RDU server is restarted.
Write-ahead logging requires these conditions to work properly:
a.
The file system and physical storage must be setup such that they guarantee that the data is flushed
to physical storage when requested. For example, a storage system with RAM-only write cache,
which loses data during system failure, is not appropriate. However, a disk array with battery-backed
write cache that guarantees that the data gets persisted, even in the event of a system failure, is
acceptable.
to physical storage when requested. For example, a storage system with RAM-only write cache,
which loses data during system failure, is not appropriate. However, a disk array with battery-backed
write cache that guarantees that the data gets persisted, even in the event of a system failure, is
acceptable.
b.
The file system must be setup with 8192 byte block size to match the RDU database block size. This
is usually the default setting on Solaris unless explicitly adjusted.
is usually the default setting on Solaris unless explicitly adjusted.
Database Files
The RDU database stores data in binary files using the file system you have mounted on the partition
containing the files. It is essential to choose and configure a file system such that it is not susceptible to
long recovery times after system failures.
containing the files. It is essential to choose and configure a file system such that it is not susceptible to
long recovery times after system failures.