Mode Settings

Last updated on 2016-05-05 15:12:11

The Mode box contains several settings that control

the type of backup
how automatic verify is performed,
how to treat used media
what to do when a file won't fit on the current media.

Many of these settings are set automatically when a schedule rotation is in effect. When a rotation controls these settings, they are disabled in the Administrator.

Backup Mode

Yosemite Server Backup supports the backup modes listed below. For scheduled automatic rotation jobs, Yosemite Server Backup uses the backup mode for each backup set as indicated on the Schedule page; for unscheduled or manual jobs, Yosemite Server Backup uses the settings set by the user.

Setting	Description
Full	This setting instructs Yosemite Server Backup to back up all selected files.
Differential	This setting instructs Yosemite Server Backup to back up all selected files that have changed since the last full backup.
Incremental	This setting instructs Yosemite Server Backup to back up all selected files that have changed since the last full, differential, or incremental backup.
Copy	This setting instructs Yosemite Server Backup to back up all selected files, but it has no effect on any future scheduled job. Use this option when you wish to make a record of files or systems at a particular time, but do not wish to disrupt the normal backup schedule.

Incremental jobs are the shortest and smallest jobs to run, but they present some issues related to full data recovery. The difference between an incremental and a differential backup is important -- incremental backup jobs back up only files that have changed since the last full, differential or incremental backup, while differential backup jobs back up all files changed since the last full backup. If incremental backup media sets are overwritten or recycled before another full backup is performed, this can create a gap in available data if you need to recover files from the overwritten media.

Exclusive use of incremental backup jobs to ensure full data recovery after a disaster is not recommended, unless you are using a schedule that retains one full backup and all subsequent incremental backups before overwriting any media. However, to ensure successful data recovery with incremental jobs, follow these guidelines:

Have at least as many incremental media as there are days between full or differential backup jobs. For example, if you run full backup jobs every five days, have at least four incremental media; if you run full backup jobs every seven days, have at least six incremental media.

Never recycle incremental media between differential or full backup jobs. If you run more than one incremental job in a row, be certain to not recycle any of the media used during this string of incremental jobs.

Auto Verify Mode

After Yosemite Server Backup backs up a set of data, it can verify that the data was backed up correctly. Yosemite Server Backup reads the files from the media and performs the selected verification type. If any discrepancies between the two files are found, the file is reported in the job log.

Verification Type	Description
Full Verify	This setting instructs Yosemite Server Backup to compare every selected file stored on the media with the original file from the PC desktop or file or application server. If the file has changed since it was backed up, the full verify process will report that the file on the media does not match the file on disk. This does not mean that the backup was unsuccessful.
Quick Verify	This setting instructs Yosemite Server Backup to be certain that every file backed up onto the media is in readable condition. It does not verify that the data matches the file, only that the data stored on the media can be read.
No Verify	This setting instructs Yosemite Server Backup to skip the verification step. It is not recommended.

Verifying that data has been correctly written to the media is an essential part of a comprehensive backup program. Also, verifying the files ensures that the media and the media drive are working correctly.

Write Mode

For automatic rotation jobs, Yosemite Server Backup overwrites all media. For other jobs, Yosemite Server Backup uses the write mode settings set by the user. This mode determines whether the old data on the media is overwritten with new data or whether the new data is appended to the end of the old data. When media is overwritten, all of the data previously stored on it is lost. Appending data will preserve the old data.

Setting	Description
Append to all media	This setting instructs Yosemite Server Backup to append all data to the end of the media. No data is overwritten. Select this setting for permanent storage.
Append to first media, overwrite others	Append to first media, overwrite others
Overwrite all media	This setting instructs Yosemite Server Backup to overwrite all media. All data on media that is overwritten is lost. Use this option for media that are going to be recycled.

Split File

The Split File mode determines how Yosemite Server Backup will handle a file if the file is too large to fit on the current media. Selecting this option to instruct Yosemite Server Backup to split a file across two media if it will not fit on the current backup media. If this option is not selected then file that don't fit on the media will be restarted on the next media.

If you use the split file option, files that span two media will require both media for restore. If one is lost then the file cannot be recovered.

Files protected with split file mode cannot be restored during Disaster Recovery. They must be restored after the DR process has completed.

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