Lenovo ThinkServer RD240 MegaRAID SAS Software User Guide - Page 61
Maximizing Performance, A RAID disk subsystem improves I/O performance. The RAID drive
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RAID Level Fault Tolerance 6 Combines distributed parity with disk striping. RAID 6 can sustain two drive failures and still maintain data integrity. Parity provides redundancy for two drive failures without duplicating the contents of entire drives. If a drive fails, the RAID controller uses the parity data to reconstruct all missing information. In RAID 6, this method is applied to entire drives or stripes across all of the drives in a drive group. Using distributed partiy, RAID 6 offers fault tolerance with limited overhead. 00 Does not provide fault tolerance. All data in a virtual drive is lost if any drive in that virtual drive fails. Disk striping writes data across multiple drives instead of just one drive. It involves partitioning each drive storage space into stripes that can vary in size. RAID 00 is ideal for applications that require high bandwidth but do not require fault tolerance. 10 Provides complete data redundancy using striping across spanned RAID 1 drive groups. RAID 10 works well for any environment that requires the 100 percent redundancy offered by mirrored drive groups. RAID 10 can sustain a drive failure in each mirrored drive group and maintain drive integrity. 50 Provides data redundancy using distributed parity across spanned RAID 5 drive groups. RAID 50 includes both parity and disk striping across multiple drives. If a drive fails, the RAID controller uses the parity data to recreate all missing information. RAID 50 can sustain one drive failure per RAID 5 drive group and still maintain data integrity. 60 Provides data redundancy using distributed parity across spanned RAID 6 drive groups. RAID 60 can sustain two drive failures per RAID 6 drive group and still maintain data integrity. It provides the highest level of protection against drive failures of all of the RAID levels. RAID 60 includes both parity and disk striping across multiple drives. If a drive fails, the RAID controller uses the parity data to recreate all missing information. 2.6.2 Maximizing Performance A RAID disk subsystem improves I/O performance. The RAID drive group appears to the host computer as a single storage unit or as multiple virtual units. I/O is faster because drives can be accessed simultaneously. Table 2.14 describes the performance for each RAID level. RAID Configuration Strategies 2-29