HP Data Protector Software Performance White Paper

across slow LAN (100 Mb/s) environments. This could provide a better backup performance,

but it will also cause high CPU loads on the client server.

• When backing up typical files directly to a SCSI-attached Ultrium 960 tape drive, parallel

backups (multiplexing/concurrency) are recommended because one single stream cannot fully

use the tape drive. Data Protector’s default concurrency is four.

• When backing up typical files via Gigabit Ethernet HBAs to a remote Ultrium 960 tape drive,

consider performing backups without multiplexing/concurrency. The network is often the

bottleneck and enabling multiplexing/concurrency does not significantly improve the

performance.

• Backup performance can be generally improved if setting the following options to ON:

– Do not preserve access time attributes

– Do not use archive attribute (Windows specific option)

• When backing up Windows NTFS file systems with typical files striped across multiple

physical disks, enable the asynchronous reading option (introduced with Data Protector 6.1).

• For Windows NTFS file systems with millions of small files, parallel backups with a high

concurrency are recommended. These kinds of file systems are very slow and should be

multiplexed. Instead of the fast Ultrium 960 tape drive, consider using a slower Ultrium tape

drive, or backup-to-disk technology.

• For Windows NTFS file systems with millions of small files, disable double tree walks. The first

tree walk briefly scans the files selected for the backup and calculates its size, so that the

percentage done can be calculated during the backup. The second tree walk is executed

during the actual file backup. On these particular systems, it is advisable to set the following

parameter in the Data Protector template Data_Protector_home\omnirc:

– DP 6.0: NoTreeWalk=1

– DP 6.1: OB2NOTREEWALK=1

• For Windows NTFS file systems with millions of small files, consider using the Windows

Change Log Provider for incremental backups. It will also address the tree walk issue, but

only for incremental backups.

• For restores of Windows NTFS file systems with millions of small files, it is advisable to start

only one restore session. Parallel restores will cause an overflow of the Windows system

paged pool. You could also tune the Windows kernel, but this is not focus of this white paper.

• For Exchange Servers, the recommended device concurrency is two for devices connected

directly and one for devices connected remotely (backup server).