Lenovo ThinkServer RD240 MegaRAID SAS Software User Guide - Page 39
Patrol Read, 2.4.9 Disk Striping, Example of Disk Striping RAID 0 - review
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2.4.8 Patrol Read Patrol read involves the review of your system for possible drive errors that could lead to drive failure and then action to correct errors. The goal is to protect data integrity by detecting drive failure before the failure can damage data. The corrective actions depend on the drive group configuration and the type of errors. Patrol read starts only when the controller is idle for a defined period of time and no other background tasks are active, though it can continue to run during heavy I/O processes. You can use the MegaRAID Command Tool or the MegaRAID Storage Manager to select the patrol read options, which you can use to set automatic or manual operation, or disable patrol read. See Section 5.4, "Controller Property-Related Options," or Section 9.5, "Running a Patrol Read". 2.4.9 Disk Striping Disk striping allows you to write data across multiple drives instead of just one drive. Disk striping involves partitioning each drive storage space into stripes that can vary in size from 8 KB to 1024 KB. These stripes are interleaved in a repeated sequential manner. The combined storage space is composed of stripes from each drive. It is recommended that you keep stripe sizes the same across RAID drive groups. For example, in a four-disk system using only disk striping (used in RAID level 0), segment 1 is written to disk 1, segment 2 is written to disk 2, and so on. Disk striping enhances performance because multiple drives are accessed simultaneously, but disk striping does not provide data redundancy. Figure 2.1 Example of Disk Striping (RAID 0) Segment 1 Segment 5 Segment 9 Segment 2 Segment 6 Segment 10 Segment 3 Segment 7 Segment 11 Segment 4 Segment 8 Segment 12 Components and Features 2-7