The missing data can be recalculated from the data still available and the parity information. Even when one disk drive fails, all data is fully available. Additionally, the controller calculates parity information which is stored on a separate disk drive (P1, P2. RAID 4 - Data Striping With a Dedicated Parity Drive 5 drive set = 20%, 6 drive set = 17%, 10 drive set = 10%Īpplications Imaging, geological, seismological, video Many RAID controller manufacturers are moving to a RAID 4 solution or using the term RAID 3 merely as a recognized marketing term for high data transfer capability.Ĭost Per Megabyte Varies. This represents a practical implementation problem for RAID 3. Because the data must be presented at the same time, the disk drive spindles must be synchronized for RAID 3 to be effective. This data calculation can also be used to restore data to a replaced defective disk. The data is striped at a byte/bit level across the disk drives.Īdditionally, the controller calculates parity information which is stored on a separate disk drive (aP, bP. RAID 3 Data Bit Striping With a Dedicated Parity Drive The major draw back is a 100% "Cost Per Megabyte Penalty".Īpplications Multiuser environments, database servers, file serving, web site hosting. Similar as in RAID 0, optimum performance is achieved in highly sequential load situations. RAID 0+1 disk sets offer good performance and data security. The idea behind RAID 0+1 is simply based on the combination of RAID 0 (Performance) and RAID 1 (Data Security). RAID 0 + 1 - Combination of RAID 1 and RAID 0 Use RAID 1 when large volumes of data are not required.Īpplications Small disk capacities that require redundancy RAID 1 represents a simpleĪnd highly efficient solution for data security and system availability. If each disk drive is connected with a separate SCSI channel, this is called "Disk Duplexing" (additional security and performance).
CPUCOOL CRACK UPDATE
The RAID controller will update the read drive with data from the already written disk drive. If one disk is busy writing the other disk drive can supply read data, at a later time. If multiple read requests are pending, the RAID controller will allows reads from different disk drives. Performance is gained by splitting of functions. When one disk drive fails, all data is immediately available on the other without any impact on the data integrity -performance in degraded mode is also degraded.
All data is stored twice on two or more identical disk drives. RAID 1 mirrors (shadows) one disk drive to another. RAID 0 does not provide any data redundancy - if one drive fails, all data is lost.Īpplications Large disk requirements, high performance databases RAID 0 allows a number of disk drives to be combined and presented as one large disk. RAID (Redundant Array of Independent Disks) Primer
0 kommentar(er)
