FAQ
Storage/RAID technology
What is RAID? What is JBOD? How do they work together?
A RAID system provides the following benefits:
Fault Tolerance:
All hardware can fail. A failed component can be replaced. However, a disk drive failure destroys the data within. RAID technologies provide fault tolerance for disk drives by combining multiple disk drives into one or more logical arrays. If a single drive fails, data can still be retrieved from other members of a RAID array. A RAID1/3/5 array can sustain a single drive failure (more with RAID1 if the failed drives still have a mirror); a RAID6 array can withstand simultaneous failures of two members.
Performance Gain:
RAID also provides combined performance by simultaneous disk access. For example, the performance of a RAID0 array approximates the mechanical speed of individual drive times the number of drives within an array.
The performance of the arrays composed in other RAID levels will be slightly reduced because of the efforts on extra reads and writes and the parity computation.
An advanced RAID system is also capable of algorithms that facilitate performance handling I/Os of various characteristics.
RAID system:
Infortrend only provides external RAID systems. An external RAID system is an enclosure powered by a single or redundant RAID controllers, and consists of power supplies, ventilation system, and other enclosure devices that provide the ease of maintenance. The RAID controllers distribute the I/O requests to individual disk drives and provide fault tolerance by managing the logical array configurations and generating parity blocks through XOR computation.
JBOD:
A JBOD (Just a Bunch of Drives) is a drive enclosure that accommodates multiple disk drives. These drives are interfaced through a common backplane and are accessed through JBOD controllers that provide either the Fibre Channel bypass or SAS expander functionality. The JBOD enclosures attach to a managing RAID system, thus providing an easy means to quickly expand array capacity to many folds.
Infortrend does not provide JBODs that attach to 3rd-party RAID cards or HBAs.