Checking Data Integrity ensures that the backup data has not been modified after being sent to the backup media.
During various transfers from one media to another, there is a remote possibility that such a change has happened and restoring from such altered data may not give the desired result.
The Data Integrity page reads and verifies that backed up data image on the media has not been modified. In the case of application clients (such as Windows Oracle), the check does not proceed beyond determining whether the tape is readable. In this case, the message “Could not determine validation for dumper“ is displayed and logged. This message can be safely ignored.
If you verify by date, all the tapes associated with each backup run on the selected date are verified (in most cases there will be only one run per day). If you verify by label, only a particular tape is verified. The correct tape(s) must be loaded in the tape device. Verification of each backup run begins by listing the tape(s) required for that run, and then prompting you to load each tape as necessary until all have been checked.
The Data Integrity page lets you check out that the already-written media (selected by either date or label) has not been altered after the backup. Run the Data Integrity before restoring a backup image.
The default method of invoking a Data Integrity report is by Tape label.
From the Please select verification method drop down box the method of verification can be changed to By Date. Selecting by date displays the appropriate interface controls.
The Select by Tape Label dialog is displayed in the left panel by default. It allows you to select an Amanda tape by volume from the dropdown menu. Click the Verify button to start the data integrity check of the selected tape.
On choosing 'By Date' option the GUI opens to a page with the Calender control in left hand panel, with the current month selected for display. Use the calendar controls to change as desired.
The top portion consists of a Backup Date input box along with a Go button. Clicking Go displays the given date in the Calandar. The input box accepts dates in both mm/dd/yyyy and mm/dd/yy formats.
The Calendar control at the bottom of the panel works the same as it does for the Summary Report. Click the Verify button to start the data integrity check for all the tapes used by the selected backup date.
The right hand panel displays the status of the verification process. The text in the upper right (No 3) changes to indicate that the Data Verification process has started, displaying progress and any errors encountered.
ZMC gives different types of error messages that originate from the Tape device. If a verification task is already in progress, a second data verification task cannot be started for the same backup set. If this is done the following error message is displayed.
The error messages are verbose to make it easy to determine what the error were.
One Example is given below:
To clear old messages, click the Clear Output hyper link present at Upper Right Hand corner in Rectangle 2. Clicking it will restore the page to a initial clean status from where the Verify by Date test can be re-run.