Backs up an SAP Sybase IQ database on one or more archive devices.
BACKUP DATABASE [ backup-option… ] TO archive_device [ archive-option... ] … [ WITH COMMENT string ]
{ READWRITE FILES ONLY | READONLY dbspace-or-file [, … ] } CRC { ON | OFF } ATTENDED { ON | OFF } BLOCK FACTOR integer { FULL | INCREMENTAL | INCREMENTAL SINCE FULL } VIRTUAL { DECOUPLED | ENCAPSULATED ‘shell_command’ } WITH COMMENT comment
{ DBSPACES identifier-list | FILES identifier-list }
identifier [, … ]
SIZE integer STACKER integer
BACKUP DATABASE INCREMENTAL SINCE FULL TO '/dev/rmt/0n' SIZE 10000000 TO '/dev/rmt/2n' SIZE 15000000
BACKUP DATABASE READONLY DBSPACES dsp1 TO '/dev/rmt/0'
BACKUP DATABASE READONLY FILES dsp1_f1, dsp1_f2 TO 'bkp.f1f2'
BACKUP DATABASE READONLY DBSPACES dsp2, dsp3 READONLY FILES dsp4_f1, dsp5_f2 TO 'bkp.RO'
The SAP Sybase IQ database might be open for use by many readers and writers when you execute a BACKUP command. It acts as a read-only user and relies on the Table Level Versioning feature of SAP Sybase IQ to achieve a consistent set of data.
BACKUP implicitly issues a CHECKPOINT prior to commencing, and then it backs up the catalog tables that describe the database (and any other tables you have added to the catalog store). During this first phase, SAP Sybase IQ does not allow any metadata changes to the database (such as adding or dropping columns and tables). Correspondingly, a later RESTORE of the backup restores only up to that initial CHECKPOINT.
The BACKUP command lets you specify full or incremental backups. You can choose two kinds of incremental backups. INCREMENTAL backs up only those blocks that have changed and committed since the last BACKUP of any type (incremental or full). INCREMENTAL SINCE FULL backs up all of the blocks that have changed since the last full backup. The first type of incremental backup can be smaller and faster to do for BACKUP commands, but slower and more complicated for RESTORE commands. The opposite is true for the other type of incremental backup. The reason is that the first type generally results in N sets of incremental backup archives for each full backup archive. If a restore is required, a user with the SERVER OPERATOR system privilege must RESTORE the full backup archive first, and then each incremental archive in the proper order. (SAP Sybase IQ keeps track of which ones are needed.) The second type requires the user with the SERVER OPERATOR system privilege to restore only the full backup archive and the last incremental archive.
Incremental virtual backup is supported using the VIRTUAL DECOUPLED and VIRTUAL ENCAPSULATED parameters of the BACKUP statement.
Although you can perform an OS-level copy of tablespaces to make a virtual backup of one or more read-only dbspaces, use the virtual backup statement, because it records the backup in the SAP Sybase IQ system tables.
READWRITE FILES ONLY may be used with FULL, INCREMENTAL, and INCREMENTAL SINCE FULL to restrict the backup to only the set of read-write files in the database. The read-write dbspaces/files must be SAP Sybase IQ dbspaces.
If READWRITE FILES ONLY is used with an INCREMENTAL or INCREMENTAL SINCE FULL backup, the backup will not back up data on read-only dbspaces or dbfiles that has changed since the depends-on backup. If READWRITE FILES ONLY is not specified for an INCREMENTAL or INCREMENTAL SINCE FULL backup, the backup backs up all database pages that have changed since the depends-on backup, both on read-write and read-only dbspaces.
The keyword INCREMENTAL is not allowed with READONLY FILES.
BACKUP and RESTORE write your SAP Sybase IQ data in parallel to or from all of the archive devices you specify. The catalog store is written serially to the first device. Faster backups and restores result from greater parallelism.
SAP Sybase IQ supports a maximum of 36 hardware devices for backup. For faster backups, specifying one or two devices per core will help to avoid hardware and IO contention. Set the SIZE parameter on the BACKUP command to avoid creating multiple files per backup device and consider the value used in the BLOCK FACTOR clause on the BACKUP command.
BACKUP overwrites existing archive files unless you move the old files or use a different archive_device name or path.
The backup API DLL implementation lets you specify arguments to pass to the DLL when opening an archive device. For third-party implementations, the archive_device string has this format:
'DLLidentifier::vendor_specific_information'
A specific example:
'spsc::workorder=12;volname=ASD002'
The archive_device string length can be up to 1023 bytes. The DLLidentifier portion must be 1 to 30 bytes in length and can contain only alphanumeric and underscore characters. The vendor_specific_information portion of the string is passed to the third-party implementation without checking its contents. Do not specify the SIZE or STACKER clauses of the BACKUP command when using third-party implementations, as that information should be encoded in the vendor_specific_information portion of the string.
For the Sybase implementation of the backup API, you need to specify only the tape device name or file name. For disk devices, you should also specify the SIZE value, or SAP Sybase IQ assumes that each created disk file is no larger than 2GB on UNIX, or 1.5GB on Windows. An example of an archive device for the SAP Sybase API DLL that specifies a tape device for certain UNIX systems is:
'/dev/rmt/0'
Units are kilobytes (KB), although in general, less than 1GB is inappropriate. For example, for a 3.5GB tape, specify 3500000. Defaults are by platform and medium. The final size of the backup file will not be exact, because backup writes in units of large blocks of data.
The SIZE parameter is per output device. SIZE does not limit the number of bytes per device; SIZE limits the file size. Each output device can have a different SIZE parameter.
During backup, when the amount of information written to a given device reaches the value specified by the SIZE parameter, BACKUP does one of the following:
It is your responsibility to mount additional tapes if needed, or to ensure that the disk has enough space to accommodate the backup.
When multiple devices are specified, BACKUP distributes the information across all devices.
Platform |
Default SIZE for tape |
Default SIZE for disk |
---|---|---|
UNIX |
none |
2GB |
Windows |
1.5GB SIZE must be a multiple of 64. Other values are rounded down to a multiple of 64. |
1.5GB |
Other issues for BACKUP include:
BACKUP does not support raw devices as archival devices.
Windows systems support only fixed-length I/O operations to tape devices (for more information about this limitation, see your Installation and Configuration Guide). Although Windows supports tape partitioning, SAP Sybase IQ does not use it, so do not use another application to format tapes for BACKUP. Windows has a simpler naming strategy for its tape devices, where the first tape device is \\.\tape0, the second is \\.\tape1, and so on.
SAP Sybase IQ does not rewind tapes before using them. You must ensure the tapes used for BACKUP or RESTORE are at the correct starting point before putting them in the tape device. SAP Sybase IQ does rewind tapes after using them on rewinding devices.
During BACKUP and RESTORE operations, if SAP Sybase IQ cannot open the archive device (for example, when it needs the media loaded) and the ATTENDED parameter is ON, it waits for ten seconds and tries again. It continues these attempts indefinitely until either it is successful or the operation is terminated with a Ctrl+C.
If you enter Ctrl+C, BACKUP fails and returns the database to the state it was in before the backup started.
If disk striping is used, such as on a RAID device, the striped disks are treated as a single device.
Automatic commit
SQL—Vendor extension to ISO/ANSI SQL grammar.
Sybase—Not supported by Adaptive Server Enterprise.