When you perform an online backup of a Microsoft Exchange
2000 Server, you may notice the time that it takes to backup the database
slowly increases over time. The time it takes to complete a backup of
comparable size may double from the time it took in the first few weeks of
operation.
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To resolve this issue, click to clear the
Zero out
deleted database pages check box on the properties of the Storage
Group. To do so, follow these steps:
| 1. | Click Start, point to
Programs, point to Microsoft Exchange, and
then click System Manager. |
| 2. | In the left pane, double-click Administrative
Groups, click your administrative group, and then double-click your
server. |
| 3. | Right-click your storage group, and then click
Properties. |
| 4. | Click to clear the Zero out deleted database
pages check box. |
| 5. | Click OK. |
| 6. | Restart the Information Store service so that the change will take effect. |
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The Zero out deleted database pages option
is designed to overwrite unused pages in the Exchange 2000 Server databases
with zeros so that the data in these unused pages cannot be recovered by using
conventional means.
When an item is deleted from the Exchange Server,
such as when a user deletes a message from their mailbox, the item is no longer
referenced and the pages that the item was occupying are marked as unused. With
Zero out deleted database pages selected, the data contained
in unused pages is overwritten with various characters (either 'z', 'd', 'l',
or 'u', depending on the type of page being overwritten) during an online
backup. As each database page is written to the tape, the page is then
overwritten with zeros in the database on the hard disk. After the backup is
complete, the deleted data is on the tape but is no longer in the database and
cannot be recovered by using conventional means.
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