Tuning Recommendations
General
•Ensure the Ultra320 SCSI HBA for the tape drive is placed on a dedicated
•For all HP StorageWorks Ultrium 960 backups, HP recommends the Tape Block Size be configured to 256 KB.
•Match file library block size to tape drive block size. When using a secondary subsystem as a file library for backups, it is important to give it the same block size as the tape device that will be used in the final part of the data protection process. So in the case of HP StorageWorks Ultrium 960 tape drive, this would be 256 KB. Different block size between source and target medium will cause block repackaging which has an performance impact in regards to additional CPU load, CRC processing (if enabled) and shared memory utilization.
•Disable double tree walks for file systems with millions of small files. 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 recommended to set the option “NoTreeWalk=1” in the Data Protector configuration file “<Data_Protector_home>\omnirc”.
•In Windows environments, configure smaller file depot sizes for better performance. Creating larger files requires more CPU and memory resources. For similar environments the recommended Maximum File Depot Size is 10 – 50 GB.
•Windows memory problems can occur during high performance backups. This is a general Windows kernel problem and applies to all backup applications – including NTBACKUP. The Data Protector error message looks like:
[Major] From: VBDA@tpc131.bbn.hp.com "G:" Time: 29.03.2005 19:08:57 [81:78] G:\1\file67108864_000003
Cannot read 57256 bytes at offset 0(:1): ([1450] Insufficient system resources exist to complete the requested service. ).
A Microsoft article (Q304101) has been found that explains the circumstances that can lead to this error and how to fix it.
Note: It's suggested to follow the instructions in Microsoft article Q304101, where causes and settings for avoiding memory problems are described. The link to this article:
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