Configuring RAID for Optimal Performance

Configuring RAID for Optimal Performance Overview
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Table of Contents
1. Overview ...............................................................................................................................3
2. Performance Measurement Tools.......................................................................................3
2.1 Copying large files ...................................................................................................3
2.2 Tools without queuing..............................................................................................3
2.3 IOmeter* ..................................................................................................................4
2.4 Measuring Performance under Linux.......................................................................4
3. Optimal RAID Settings.........................................................................................................5
4. Impact of RAID Settings on Performance ..........................................................................6
4.1 Write Policy..............................................................................................................6
4.1.1 Write Back Mode .....................................................................................................6
4.1.2 Write Thru Mode......................................................................................................6
4.2 Disk Cache Policy....................................................................................................6
4.3 Read Ahead Policy ..................................................................................................7
4.3.1 No Read Ahead (Normal) ........................................................................................7
4.3.2 Always Read Ahead ................................................................................................7
4.3.3 Adaptive Read Ahead..............................................................................................7
4.4 I/O Policy .................................................................................................................7
4.4.1 Direct I/O..................................................................................................................7
4.4.2 Cached I/O...............................................................................................................7
4.5 Strip Size .................................................................................................................7
5. Other Performance Factors.................................................................................................8
5.1 Backup Battery Status .............................................................................................8
5.2 Virtual Drive Initialization .........................................................................................8
5.3 Patrol Read..............................................................................................................8
5.4 Consistency Check..................................................................................................9
5.5 Data Location on Physical Drives............................................................................9
5.6 PCI Express* Slot ....................................................................................................9
5.7 Vibration...................................................................................................................9
5.8 Overheating ...........................................................................................................10