Memory for disk arrays
Recruitment levels supported IDE RAID controllers, considerably more modest.
Usually it is zero and the first levels. In addition, controllers found that
support a combination of the fifth level and the first and zero: 0 +1. This
approach is zakonomeren because IDE RAID controllers are in the first regular-turn
for workstations, so the emphasis is on increasing the security of data (level 1)
and productivity, along with the withdrawal of-entry (level 0). The scheme of
independent disks in this case is not needed, because workstations flow of
requests for read / write significantly lower than, say, servers. The primary
function of RAID array is not an increase in capacity disk subsystem (as can be
seen from its devices, the same capacity and can be obtained for lower cost),
and ensure the reliability of your data and increase productivity. For servers,
in addition, require continuity in the work, even in the event of failure of one
of the drives. Continuity of the work is ensured by a hot comments are, ie
extraction faulty SCSI disk, and without installing a new switch off the power
supply. By because when one drives defective disk subsystem continues to work (except
level of 0), replacement of hot provides rehabilitation, transparent to users.
However, the rate of transmission and access speed, with one dead drive
noticeable decrease dropping from the fact that the controller must restore the
data from the redundant information. True, this rule is an exception - RAID
Storage Systems Levels 2, 3, 4, with failure of the on-kopitelya abnormal
information to begin work faster! This is natural, since in a coma-level event "on
the fly" is changed to zero, which has a magnificent high-speed characteristics.
There are several types of RAID controller, depending on their functional
capabilities, design and cost. i. Floppy disk controllers with RAID. In fact, it
is an ordinary disk controller, which is due to the special-kyo riddling BIOS
allows the disk drives in RAID-array tend to level 0, 1 or 0 +1.