Nytro MegaRAID Revision 1.7 Overview : Nytro MegaRAID Controller Features and Benefits : R1-Elastic Cache

R1-Elastic Cache

R1-elastic cache (R1-EC), a new RAID protection from LSI for the Nytro Flash modules.The R1-elastic cache feature of Nytro MegaRAID accelerates the I/O throughput and enhances the endurance of the Nytro Cache drive. R1-elastic cache is another protection level along with RAID 1 and RAID 0. In elastic cache, host-writes are mirrored and host-reads are not mirrored.

When the data get mirrored on both drives, the logical block address would be different from one another as opposed to RAID 1. That is, the second drive is not a replica of the first drive in an array as shown in the following figure.

Figure 1. R1-Elastic Cache (EC) Block

The size of R1-elastic cache (EC) would be larger than RAID 1 Nytro Cache drive and lesser than RAID 0 Nytro Cache drive. This is achieved by mirroring only the host-written data. Because of this, the usable capacity of the Nytro Cache drive depends on the I/O from the host.