Moving database files

If you need to move database files to a new location—for example, if one of your disk drives fails—you use one of the following methods:

When restoring to a raw device, make sure that the device is large enough to hold the dbspace being restored. IQ RESTORE checks the raw device size and returns an error, if the raw device is not large enough to restore the dbspace.

The operating system takes a small amount of space on the raw device and the IQ dbspace occupies the rest. When you restore the dbspace, your raw partition must hold both the IQ dbspace and the space reserved for the operating system.

To restore an IQ Main or Temporary dbspace to a raw partition, find the raw device size needed for each IQ dbspace from system tables as follows:

SELECT segment_type, file_name, block_count, data_offset, block_size, (block_count * block_size) + data_offset AS raw_size FROM SYS.SYSIQFILE, SYS.SYSINFO where segment_type !=’Msg’ ORDER BY 1,2 

The segment_type and file_name are informational. Segments of type ‘Main’ or ‘Temp’ may be stored on a raw partition, but message files (type ‘Msg’) may not. The file_name is the name of the dbspace.

The block_count column is an integer, the number of blocks used by IQ.

The data_offset column is an integer, the number of bytes reserved for the operating system.

The block_size column is an integer, the number of bytes per IQ block.

The raw_size column is an integer, the minimum size in bytes of a raw device needed to restore this dbspace. Sybase recommends restoring to a raw device that is at least 10MB larger than the original raw device.

This example restores the same database as Example 1. In Example 2, however, you move the Catalog Store file and any database files that were created relative to it. To do so, you replace the original file name with its new location, c:\newdir, as follows:

RESTORE DATABASE 'c:\\newdir\\asiqnew.db'
FROM 'c:\\asiq\\backup1'
FROM 'c:\\asiq\\backup2'

Sybase IQ moves database files other than the Catalog Store as follows:

• If you specify a RENAME clause, the file is moved to that location.

• If you do not specify a RENAME clause, and the file was created using a relative pathname, it is restored relative to the new location of the database file. In other words, files originally created relative to the SYSTEM dbspace, which holds the Catalog Store file, are restored relative to the Catalog Store file. Files originally created relative to the IQ_SYSTEM_MAIN dbspace, which holds the main IQ Store file, are restored relative to the main IQ Store file.

• If you do not specify a RENAME clause, and the file was created using an absolute pathname, the file is restored to its original location.

In other words, if you want to move an entire database, you should specify in a RENAME clause the new location for every IQ dbspace in the database—required, temporary, and user-defined. The SYSTEM dbspace is the only one you do not include in a RENAME clause.

If you only want to move some of the files, and overwriting the original files is not a problem, then you only need to rename the files you actually want to move.

You specify each dbspace_name as it appears in the SYSFILE table. You specify new_dbspace_path as the new raw partition, or the new full or relative pathname, for that dbspace.

You cannot use the RENAME option to specify a partial restore.

Relative pathnames in the RENAME clause work as they do when you create a database or dbspace: the main IQ Store dbspace, Temporary Store dbspaces, and Message Log are restored relative to the location of db_file (the Catalog Store); user-created IQ Store dbspaces are restored relative to the directory that holds the main IQ dbspace.

If you are renaming files while restoring both full and incremental backups, be sure you use the dbspace names and paths consistently throughout the set of restores. It is the safest way to ensure that files are renamed correctly.

If a dbspace was added between the full backup and an incremental backup, and you are renaming database files, you need one more RENAME clause for the incremental restore than for the full restore. Similarly, if a dbspace was deleted between backups, you need one fewer RENAME clause for the restores from any backups that occurred after the dbspace was deleted.

This example shows how you restore the full and incremental backups in the example shown earlier in this chapter. In this case, media failure has made a UNIX raw partition unusable. The user-defined dbspace on that raw partition, IQ_USER, must be moved to a new raw partition, /dev/rdsk/c1t5d2s1. No other database files are affected.