RAID 4 is a Redundant Array of Independent Disks standard configuration that utilizes a dedicated parity disk and block-level data stripping across various disks. Since data in RAID 4 array is stripped, the records can be read from any disk. RAID 4 doesn’t require synchronized spinning, and each disk works independently when single data blocks are requested. It is similar to RAID 5, but it doesn’t distribute parity bits. RAID 4 configuration requires a minimum of three disks (two disks for data and one for parity).
Here are some of the salient advantages of using RAID 4 array:
• Good random reads as the data blocks are stripped
• Bad random writes because for every write it has to write to the single parity disk
• It is very much similar to RAID 5, so far stripping the blocks the data disks is concerned, but it has only one parity disk.
• In having dedicated parity disk, RAID 4 is just like RAID 3, but RAID 4 stripes blocks.
• RAID 4 is rarely used.