Lenovo ThinkServer RD330 MegaRAID SAS Software User Guide - Page 36
Example of Distributed Parity across Two Blocks in a Stripe RAID 6, Table 11, RAID 00
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Chapter 2: Introduction to RAID | RAID Levels MegaRAID SAS Software User Guide 2.5.7 RAID 00 Segment 1 Segment 6 Segment 11 Segment 16 Parity (P17-P20) Segment 2 Segment 7 Segment 12 Parity (P13-P16) Parity (Q17-Q20) Segment 3 Segment 8 Parity (P9-P12) Parity (Q13-Q16) Segment 17 Segment 4 Parity (P5-P8) Parity (Q9-Q12) Segment 13 Segment 18 Parity (P1-P4) Parity (Q5-Q8) Segment 9 Segment 14 Segment 19 Parity (Q1-Q4) Segment 5 Segment 10 Segment 15 Segment 20 Note: Parity is distributed across all drives in the drive group. Figure 10: Example of Distributed Parity across Two Blocks in a Stripe (RAID 6) A RAID 00 drive group is a spanned drive group that creates a striped set from a series of RAID 0 drive groups. RAID 00 does not provide any data redundancy, but, along with RAID 0, does offer the best performance of any RAID level. RAID 00 breaks up data into smaller segments and then stripes the data segments across each drive in the drive groups. The size of each data segment is determined by the stripe size. RAID 00 offers high bandwidth. NOTE: RAID level 00 is not fault tolerant. If a drive in a RAID 0 drive group fails, the whole virtual drive (all drives associated with the virtual drive) will fail. By breaking up a large file into smaller segments, the RAID controller can use both SAS drives and SATA drives to read or write the file faster. RAID 00 involves no parity calculations to complicate the write operation. This makes RAID 00 ideal for applications that require high bandwidth but do not require fault tolerance. Table 11 provides an overview of RAID 00. Figure 11 provides a graphic example of a RAID 00 drive group. Table 11: RAID 00 Overview Uses Strong Points Weak Points Drives Provides high data throughput, especially for large files. Any environment that does not require fault tolerance. Provides increased data throughput for large files. No capacity loss penalty for parity. Does not provide fault tolerance or high bandwidth. All data lost if any drive fails. 2 through 256 Page 36