Sybase DC38133-01-0902-01 manual Transaction log and backup management

Chapter 11. Administering SQL Remote for Adaptive Server

Anywhere

Transaction log and backup management

The importance of good	Replication depends on access to operations in the transaction log, and
backup practices	access to old transaction logs is sometimes required. This section describes
	how to set up backup procedures at the consolidated and remote databases to
	ensure proper access to old transaction logs.
	It is crucial to have good backup practices at SQL Remote consolidated
	database sites. A lost transaction log could easily mean having to re-extract
	remote users. At the consolidated database site, a transaction log mirror is
	recommended.
	☞ For information on transaction log mirrors and other backup procedure
	information, see “Backup and Data Recovery” [ASA Database Administration
	Guide, page 373].
Ensuring access to old	All transaction logs must be guaranteed available until they are no longer
transactions	needed by the replication system.
	In many setups, users of remote databases may receive updates from the
	office server every day or so. If some messages get lost or deleted, and have
	to be resent by the message-tracking system, it is possible that changes made
	several days ago will be required. If a remote user takes a vacation, and
	messages have been lost in the meantime, changes weeks old may be
	required. If the transaction log is backed up daily, the log with the changes
	will no longer be running on the server.

Because the transaction log continually grows in size, space can become a concern. You can use an event handler on transaction log size to rename the log when it reaches a given size. Then you can use the DELETE_OLD_LOGS option to clean up log files that are no longer needed.

☞For more information about controlling transaction log size, see the “BACKUP statement” [ASA SQL Reference, page 307].

Setting the transaction log directory

	When the Message Agent needs to scan transaction logs other than the
	current log, it looks through all the transaction log files kept in a designated
	transaction log directory. A setting on the Message Agent command line
	tells the Message Agent which directory this is.
Example	For example, the following command line tells the Message Agent to look in
	the directory e:\archive to find old transaction logs. The command must be
	entered all on one line.
	dbremote -c "eng=server_name;uid=DBA;pwd=SQL" e:narchive

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