Manuals:
Veritas NetBackup (tm) 4.5 for Microsoft Exchange Server System Administrator's Guide on Windows NT/2000
Veritas NetBackup (tm) 5.0 for Microsoft Exchange Server System Administrator's Guide for Windows
Veritas NetBackup (tm) 5.1 for Microsoft Exchange Server System Administrator's Guide for Windows
Veritas NetBackup (tm) 6.0 for Microsoft Exchange Server System Administrator's Guide for Windows
Modification Type: Supplement
Modification:
If file system backups from the Exchange client are running at a satisfactory speed, then most likely there is no performance tuning within NetBackup which will improve the speed of mailbox backups. There are two general ways to perform baseline testing of Exchange Mailbox backup throughput for the purpose of determining the theoretical maximum possible throughput for mailbox backups:
1. The
exmerge utility from Microsoft is used to extract the data directly out of the database into a
.pst file. The utility should be used to export a few larger mailboxes, and the performance on these mailboxes can be used to gauge the time it should take to complete the backup process. The utility does create a log file which can be viewed after the process has run to gauge the amount of time the process took. Since this is a Microsoft utility, refer to this Microsoft link for operating instructions:
http://support.microsoft.com/?kbid=174197
2. The second option is a backup test to a "null" device. Backup to a null device uses the same NetBackup client processes as a normal mailbox backup, but sends the data to a null file on the Exchange server. This causes NetBackup to read all the data, but instead of transferring the information to tape to be saved, it is sent to a null device. This process mimics the backup process and is an excellent test to determine the theoretical maximum possible speed of a backup since it eliminates any potential network or tape drive speed issues from the test. This test only looks at how fast the information can be read from the Exchange database.
To test mailbox backups to a null device, go to a command prompt on the Exchange server, and change to the
<install_path>\veritas\netbackup\bin directory. From there, issue the following command, substituting the actual name of the Exchange server for the client name field:
bpbkar32 -nocont -clnt <client_name> -ct 16 Microsoft Exchange Mailboxes:\ > nul > c:\temp.out
Note: Several factors can impact mailbox backup performance:
- The creation of more message items in the database creates more data to back up, along with more fragmentation in the database, decreasing access time.
- Running an antivirus scanner in On-Access/VAPI mode causes a scan of every item backed up and significantly degrades the process.
- Database defragmentation running at the same time as the mailbox backup degrades the performance.
- Very large mailboxes with many message items have increased initial scan times and slow backup performance.
