Hitachi 8450H/R Server User Manual


 
Ch 3: Installing Optional Devices
54 Hitachi PC VisionBase8450H/R Server
RAID5
Data, together with array parity, is striped in blocks, extending over all hard disks.
Number of hard disks required: 3 (min.) to 6 (max.)
Advantages: Capacity-to-cost ratio is improved as compared with RAID1.
Data redundancy is ensured by distributing data to several hard disks; therefore, each hard disk can
perform read/write operation independently. This type of disk array is useful for transaction processing
because data is striped in block.
If a hard disk within the array fails, the lost data is computed based on the array parities, enabling the read/
write operation to continue. By replacing the hard disk, you can rebuild the data without interrupting your
current task.
Because array parities are distributed to each hard disk, you can have the advantages of parallel
processing through independent access to the hard disks when writing data.
Disadvantages: Array parities are created during write operation, so performance for write operation is not as high as
RAID0.
A read/write operation during data rebuilding will result in lower performance.