Backing Up File System Data

This section describes the recommended procedures for regularly backing up important data and files in a Sun QFS file system-only environment. For information about backing up in an archiving environment, see Creating Archive Recovery Points.

Setting Up Dump Files

File systems are made up of directories, files, and links. The file system keeps track of all the files by storing information in the .inodes file. The .inodes file resides on the metadata device. The file system writes all file data to the data devices. Depending on your configuration, the metadata device can be separate from the file system data device.

Be sure to use the qfsdump command periodically to create a dump file of metadata and file data. The dump process saves the relative path information for each file contained in a complete file system or in a portion of a file system. This protects your data in the event of a disaster.

You can create dump files as often as once or twice a day, depending on your site's requirements. By dumping file system data on a regular basis, you can restore old files and file systems. You can also move files and file systems from one server to another.

Follow these guidelines for creating dump files:

• The qfsdump command dumps file names, inode information, and data. This command creates full dumps, not incremental dumps, of specified files and directories, and the resulting file can therefore be very large. The qfsdump command does not have any tape management, size estimations, or incremental dump facilities, as does ufsdump . In addition, the qfsdump command does not support volume overflow, so you need to evaluate space considerations and make sure that the size of the file system does not exceed the size of the dump media.

• The qfsdump command dumps all the data of a sparse file, and the qfsrestore command restores all the data. These commands do not, however, preserve file qualities that enable sparse files to be characterized as sparse. Doing so could cause files to occupy more space on dump files and on restored file systems than anticipated.

• Because you issue the qfsdump command on a mounted file system, inconsistencies can arise as new files are being created on disk. Dumping file systems during a quiet period (a time when files are not being created or modified) minimizes these inconsistencies.

• Ensure that you dump metadata and data for all file systems. Look in the /etc/vfstab file for all file systems of type samfs.

You can run the qfsdump command manually or automatically. Even if you implement this command to be run automatically, you might also need to run it manually from time to time, depending on your site's circumstances. In the event of a disaster, you can use the qfsrestore command to re-create your file system. You can also restore a single directory or file.

For more information about creating dump files and restoring from them, see the qfsdump(1M) man page. The following sections describe procedures for issuing this command both manually and automatically.

Running the qfsdump Command Automatically Using cron

For each file system, make an entry in the root crontab file so that the cron daemon runs the qfsdump command periodically in your environment. Make sure you save each dump file in a separate file.

For example:

10 0 * * * (cd /qfs1; /opt/SUNWsamfs/sbin/qfsdump -f /dev/rmt/0cbn)

This entry executes the qfsdump command at 10 minutes after midnight. It uses the cd command to change to the mount point of the qfs1 file system, and it executes the /opt/SUNWsamfs/sbin/qfsdump command to write the data to tape device /dev/rmt/0cbn.

Running the qfsdump Command Manually From the Command Line

Go to the directory that contains the mount point for the file system and use the qfsdump command to write a dump file to a file system outside of the one you are dumping.

For example:

# qfsdump -f /save/qfs1/dump_file