HP Data Protector Software Performance White Paper

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HP StorageWorks Ultrium 960 tape drive configuration
For all tests with the Ultrium 960 tape drive, the block size was configured in Data Protector with
256 KB (64 KB default) as shown in Figure 30. See Getting the most performance from your HP
StorageWorks Ultrium 960 tape drive white paper (downloadable from
http://h18006.www1.hp.com/storage/tapewhitepapers.html
) for further details.
Figure 30. HP StorageWorks Ultrium 960 configuration – drive block size 256 KB (64 KB default)
File system tree walk
File system tree walks are typically problematic in Windows NTFS file systems with millions of
small files. UNIX file systems are less sensitive and respond much faster.
For each file system backup, Data Protector executes two tree walks by default:
1. The first file system tree walk is required for:
a. Running backup statistics
By default Data Protector creates backup statistics during runtime. The tree walk
scans the files selected for the backup and calculates its size, so that the progress
(percentage done) can be calculated and displayed in the Data Protector Monitor
GUI.
b. Detecting Windows NTFS hard links
NTFS hard links are detected if the advanced WINFS file system option Detect NTFS
Hardlinks is selected (default: OFF).
c. Detecting UNIX POSIX hard links
POSIX hard links are detected and backed up as links if the advanced UNIX file
system option Backup POSIX Hard Links as Files is not selected (default: OFF).
2. The second file system tree walk is required for cataloging, indexing and saving the selected
files.
Note: Disabling the first file system tree walk is only recommended in the following scenarios:
• Running unattended backup sessions
• Backing up millions of small files from Windows NTFS or UNIX file systems with the
requirement of an overall runtime decrease
• If the Windows file system does not keep any NTFS or POSIX hard links
Otherwise Data Protector would back up the entire file contents for each hard link, which
would occupy more space on the backup media.
How to disable the first tree walk for Windows NTFS:
If the advanced WINFS file system option Detect NTFS Hardlinks is not set (OFF), the first tree
walk can be disabled in the client’s OMNIRC file (Data_Protector_home\omnirc):
DP 6.0: NoTreeWalk=1
DP 6.1: OB2NOTREEWALK=1
How to disable the first tree walk for UNIX file systems:
If the advanced UNIX file system option Backup POSIX Hard Links as Files is selected (ON),