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Reference Manual: Commands

Chapter 1 Commands

dump database

Usage

Usage

• Table 1-23 describes the commands and system procedures used to back up databases:

  Table 1-23: Commands used to back up databases and logs

  To do this	Use this command
  Make routine dumps of the entire database, including the transaction log.	dump database
  Make routine dumps of the transaction log, then truncate the inactive portion.	dump transaction
  Dump the transaction log after failure of a database device.	dump transaction with no_truncate
  Truncate the log without making a backup, then copy the entire database.	dump transaction with truncate_only dump database
  Truncate the log after your usual method fails due to insufficient log space, then copy the entire database.	dump transaction with no_log dump database
  Respond to the Backup Server's volume change messages.	sp_volchanged

• If proxy tables are in the database they are be part of the database saveset. The content data of proxy tables is not included in the save; only the pointer is saved and restored.

• You cannot dump from an 11.x Adaptive Server to a 10.x Backup Server.

• You cannot have Sybase dumps and non-Sybase data (for example, UNIX archives) on the same tape.

• If a database has cross-database referential integrity constraints, the sysreferences system table stores the name--not the ID number--of the external database. Adaptive Server cannot guarantee referential integrity if you use load database to change the database name or to load it onto a different server.

  Warning!

  Before dumping a database to load it with a different name or move it to another Adaptive Server, use alter table to drop all external referential integrity constraints.

• You cannot use dump database in a user-defined transaction.

• If you issue dump database on a database where a dump transaction is already in progress, dump database sleeps until the transaction dump completes.

• When using 1/4-inch cartridge tape, you can dump only one database or transaction log per tape.

• You cannot dump a database if it has offline pages. To force offline pages online, use sp_forceonline_db or sp_forceonline_page.

• Adaptive Server database dumps are dynamic--they can take place while the database is active. However, they may slow the system down slightly, so you may want to run dump database when the database is not being heavily updated.

• Back up the master database regularly and frequently. In addition to your regular backups, dump master after each create database, alter database, and disk init command is issued.

• Back up the model database each time you make a change to the database.

• Use dump database immediately after creating a database, to make a copy of the entire database. You cannot run dump transaction on a new database until you have run dump database.

• Each time you add or remove a cross-database constraint or drop a table that contains a cross-database constraint, dump both of the affected databases.

  Warning!

  Loading earlier dumps of these databases can cause database corruption.

• Develop a regular schedule for backing up user databases and their transaction logs.

• Use thresholds to automate backup procedures. To take advantage of Adaptive Server's last-chance threshold, create user databases with log segments on a device that is separate from data segments. For more information about thresholds, see the System Administration Guide.

• The master, model, and sybsystemprocs databases do not have separate segments for their transaction logs. Use dump transaction with truncate_only to purge the log, then use dump database to back up the database.

• Backups of the master database are needed for recovery procedures in case of a failure that affects the master database. See the System Administration Guide for step-by-step instructions for backing up and restoring the master database.

• If you are using removable media for backups, the entire master database must fit on a single volume unless you have another Adaptive Server that can respond to volume change messages.

• You can specify the dump device as a literal, a local variable, or a parameter to a stored procedure.

• You cannot dump to the null device (on UNIX, /dev/null ).

• Dumping to multiple stripes is supported for tape and disk devices. Placing multiple dumps on a device is supported only for tape devices.

• You can specify a local dump device as:

  • A logical device name from the sysdevices system table

  • An absolute path name

  • A relative path name

  Backup Server resolves relative path names using Adaptive Server's current working directory.

• When dumping across the network, you must specify the absolute path name of the dump device. The path name must be valid on the machine on which Backup Server is running. If the name includes any characters except letters, numbers, or the underscore (_), you must enclose it in quotes.

• Ownership and permissions problems on the dump device may interfere with the use of dump commands. sp_addumpdevice adds the device to the system tables, but does not guarantee that you can dump to that device or create a file as a dump device.

• You can run more than one dump (or load) at the same time, as long as each uses different dump devices.

• If the device file already exists, Backup Server overwrites it; it does not truncate it. For example, suppose you dump a database to a device file and the device file becomes 10MB. If the next dump of the database to that device is smaller, the device file is still 10MB.

• If you issue a dump command without the init qualifier and Backup Server cannot determine the device type, the dump command fails. For more information, see the System Administration Guide.

• You must have a Backup Server running on the same machine as Adaptive Server. The Backup Server must be listed in the master..sysservers table. This entry is created during installation or upgrade, and should not be deleted.

• If your backup devices are located on another machine so that you dump across a network, you must also have a Backup Server installed on the remote machine.

• Dumping a database with the init option overwrites any existing files on the tape or disk.

• If you perform two or more dumps to a tape device and use the same file name for both dumps (specified with the FILENAME parameter), Adaptive Server appends the second dump to the archive device. You will not be able to restore the second dump because Adaptive Server locates the first instance of the dump image with the specified file name and restores this image instead. Adaptive Server does not search for subsequent dump images with the same file name.

• Backup Server sends the dump file name to the location specified by the with notify clause. Before storing a backup tape, the operator should label it with the database name, file name, date, and other pertinent information. When loading a tape without an identifying label, use the with headeronly and with listonly options to determine the contents.

• The name of a dump file identifies the database that was dumped and when the dump was made. However, in the syntax, file_name has different meanings depending on whether you are dumping to disk or to a UNIX tape:

  file = file_name

  In a dump to disk, the path name of a disk file is also its file name.

  In a dump to a UNIX tape, the path name is not the file name. The ANSI Standard Format for File Interchange contains a file name field in the HDR1 label. For tapes conforming to the ANSI specification, this field in the label identifies the file name. The ANSI specification only applies these labels to tape; it does not apply to disk files.

  This creates two problems:

  • UNIX does not follow the ANSI convention for tape file names. UNIX considers the tape's data to be unlabeled. Although it can be divided into files, those files have no name.

  • In Backup Server, the ANSI tape labels are used to store information about the archive, negating the ANSI meanings. Therefore, disk files also have ANSI labels, because the archive name is stored there.

  The meaning of filename changes depending on the kind of dump you are performing. For example, in the following syntax:

  dump database database_name to 'filename' with file='filename'

  • The first filename refers to the path name you enter to display the file.

  • The second filename is actually the archive name, the name stored in the HDR1 label in the archive, which the user can specify with the file=filename parameter of the dump or load command.

  When the archive name is specified, the server uses that name during a database load to locate the selected archive.

  If the archive name is not specified, the server loads the first archive it encounters.

  In both cases, file='archivename' establishes the name that is stored in the HDR1 label, and which the subsequent load uses to validate that it is looking at the correct data.

  If the archive name is not specified, a dump creates one; a load uses the first name it encounters.

  The meaning of filename in the to 'filename' clause changes according to whether this is a disk or tape dump:

  • If the dump is to tape, 'filename' is the name of the tape device,

  • If the dump is to disk, it is the name of a disk file.

  If this is a disk dump and the 'filename' is not a complete path, it is modified by prepending the server's current working directory.

• If you are dumping to tape and you do not specify a file name, Backup Server creates a default file name by concatenating the following:

  • Last seven characters of the database name

  • Two-digit year number

  • Three-digit day of the year (1-366)

  • Hexadecimal-encoded time at which the dump file was created

  For example, the file cations980590E100 contains a copy of the publications database made on the 59th day of 1998:

  Figure 1-2: File naming convention for database dumps to tape

• Dump volumes are labeled according to the ANSI tape-labeling standard. The label includes the logical volume number and the position of the device within the stripe set.

• During loads, Backup Server uses the tape label to verify that volumes are mounted in the correct order. This allows you to load from a smaller number of devices than you used at dump time.

  When dumping and loading across the network, you must specify the same number of stripe devices for each operation.

• On UNIX systems - Backup Server requests a volume change when the tape capacity has been reached. After mounting another volume, the operator notifies Backup Server by executing sp_volchanged on any Adaptive Server that can communicate with Backup Server.

• If Backup Server detects a problem with the currently mounted volume, it requests a volume change by sending messages to either the client or its operator console. The operator responds to these messages with the sp_volchanged system procedure.

• By default (noinit), Backup Server writes successive dumps to the same tape volume, making efficient use of high-capacity tape media. Data is added following the last end-of-tape mark. New dumps can be appended only to the last volume of a multivolume dump. Before writing to the tape, Backup Server verifies that the first file has not yet expired. If the tape contains non-Sybase data, Backup Server rejects it to avoid destroying potentially valuable information.

• Use the init option to reinitialize a volume. If you specify init, Backup Server overwrites any existing contents, even if the tape contains non-Sybase data, the first file has not yet expired, or the tape has ANSI access restrictions.

• Figure 1-3 illustrates how to dump three databases to a single volume using:

  • init to initialize the tape for the first dump

  • noinit (the default) to append subsequent dumps

  • unload to rewind and unload the tape after the last dump

    Figure 1-3: Dumping several databases to the same volume

Database dumps from a 32-bit version of Adaptive Server are fully compatible with a 64-bit version of Adaptive Server of the same platform, and vice-versa.

• At the beginning of a dump database, Adaptive Server passes Backup Server the primary device name of all database and log devices. If the primary device has been unmirrored, Adaptive Server passes the name of the secondary device instead. If any named device fails before the Backup Server completes its data transfer, Adaptive Server aborts the dump.

• If a user attempts to unmirror any of the named database devices while a dump database is in progress, Adaptive Server displays a message. The user executing the disk unmirror command can abort the dump or defer the disk unmirror until after the dump is complete.