User manual

GLOSSARY
134
SMART
This technology provides users with advanced warning of Disk Drive
failures thus enabling the Operating System to warn Users of potential
failure. S.M.A.R.T. was included in EIDE drives with the ATA-3 specifi-
cation.
SNMP
Since it was developed in 1988, the Simple Network Management
Protocol has become the de facto standard for inter-network manage-
ment. Because it is a simple solution, requiring little code to imple-
ment, vendors can easily build SNMP agents to their products. SNMP is
extensible, allowing vendors to easily add network management func-
tions to their existing products. SNMP also separates the management
architecture from the architecture of the hardware devices, which
broadens the base of multi-vendor support.
Volume Set
A volume set is a concatenation of storage elements that may be RAID
arrays, JBODs, or simply areas of disks that are not part of RAID ar-
rays.
Write-back
When a cache is operating in write-back mode, data written into the
cache is not immediately written out to its destination in second-
ary storage unless the heuristics governing the flushing of dirty data
demands otherwise. This methodology can improve the efficiency of
write operations under favorable circumstances. However, its use can
potentially lead to incoherencies in a system that is not protected from
power fluctuations or failures.
Write-through
When a cache is operating in write-through mode, data written into
the cache is also written to the destination secondary storage devices.
Essentially write completion does not occur until the data is written to
secondary storage. Thus the contents of the cache and the secondary
storage are always consistent. The advantage is that the possibility
of data corruption is greatly reduced. The disadvantage is that write-