Memory for disk arrays
On the front of external RAID controller can be located LCD indicator displaying
the status and parameters of the controller and keyboard for the management and
on-construction. Another feature of the construction is modularity: external
RAID controller may consist of a main "parent" Boards and the subsidiaries'
boards, which are located on the additional channels. Various models of "Daughter
" cards may contain different types of channels - Ultra Wide SCSI, LVD SCSI or
FC-AL, and these channels may be bidirectional, that is, to work as Host for the
disks connected to them, or as Drive when connected to a different controller.
Obviously, the external RAID controllers faced significantly more expensive than
similar domestic models, but the difference is worth the money at the expense of
greater opportunities outside RAID Controller. iv. Cluster disc system The
presence of bidirectional channels and External creates perceptions so call the
cluster disk system with the reliability previously unattainable. In such
systems, multiple servers are connected simultaneously with multiple RAID
controllers, which, in turn, manage a few common disk arrays, and the denial of
any component of such a system of (servers, RAID controller, drive, the power
supply, cables, etc. .) does not lead to failure of the entire system, but only
slightly reduces its productivity. Conclusions: The external RAID controllers
provide the highest level of productivity and reliability of all types of RAID
controller. Their servers can recommend to the middle and upper levels. o
Availability of FC-AL channels allows decomposed server and RAID-array a
considerable distance to protect data. o Dvunapravlennye channels allow combine
controllers and disk arrays in sverhna re-cluster.