1. INTRODUCTION
TR-824 User’s Manual
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1.2 RAID Explained
RAID - Redundant Array of Independent Disks
RAID technology manages multiple disk drives to enhance I/O performance and provide redundancy in
order to withstand the failure of any individual member, without loss of data.
SATA Raid provides four popular RAID Set types, Striped (RAID 0), Mirrored (RAID 1), a combination of
RAID 0 and RAID 1 (RAID 0+1), and Data Striping with Striped Parity (RAID 5) which will be supported
by Tekram next generation SATA products.
1.2.1 Disk Striping (RAID 0)
RAID 0 is a performance-oriented, non-redundant data mapping technique. While Striping is discussed as a
RAID Set type, it actually does not provide fault tolerance. With modern SATA and ATA bus mastering
technology, multiple I/O operations can be done in parallel, enhancing performance. Striping arrays use
multiple disks to form a larger virtual disk.
1.2.2 Disk Mirroring (RAID 1)
RAID 1 mirrors one disk drive to another. All data is stored twice on two or more identical disk drives.
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. If multiple read requests are pending, the
RAID controller will allow reading from different disk drives.
1.2.3 Combination of RAID 0 and RAID 1 (RAID 0+1)
The idea behind RAID 0+1 is simply based on the combination of RAID 0 (Performance) and RAID 1
(Data Security). RAID 0+1 disk sets offer good performance and data security. Similar as in RAID 0,
optimum performance is achieved in highly sequential load situations.
