Glyph cy-misan-v ユーザーガイド
169
Cybernetics
UM-MV-86-B1-0801
iSCSI Initiator – A device that begins an iSCSI transaction by issuing a command to
another device (the iSCSI target) to perform a task. Typically an iSCSI host bus adapter
is the initiator, but targets may also become initiators, such as when the miSAN-V-Series
is configured to use remote iSCSI devices.
another device (the iSCSI target) to perform a task. Typically an iSCSI host bus adapter
is the initiator, but targets may also become initiators, such as when the miSAN-V-Series
is configured to use remote iSCSI devices.
iSCSI Target – An iSCSI device that executes a command given by an iSCSI initiator to
perform a task. The
miSAN-V-Series is the target for an iSCSI host initiator.
perform a task. The
miSAN-V-Series is the target for an iSCSI host initiator.
Fault Tolerance – The ability of a system or component to continue normal operation
despite a hardware or software failure. This often involves some degree of redundancy.
For disk drives, complete redundancy is “Mirroring”, where every write operation is per-
formed on two or more disk drives, so if one fails the other can take over.
despite a hardware or software failure. This often involves some degree of redundancy.
For disk drives, complete redundancy is “Mirroring”, where every write operation is per-
formed on two or more disk drives, so if one fails the other can take over.
JBOD – “Just a Bunch of Disks” (JBOD) is an acronym that refers to disk drives that have
not been configured in a RAID array (See “RAID”). With JBOD, each drive is either oper-
ated independently or drives may be seen as a single drive by combining the drives into
one larger logical disk. JBOD does not provide RAID aggregation, fault tolerance or
redundancy.
not been configured in a RAID array (See “RAID”). With JBOD, each drive is either oper-
ated independently or drives may be seen as a single drive by combining the drives into
one larger logical disk. JBOD does not provide RAID aggregation, fault tolerance or
redundancy.
Job I/O – The HSTC’s disk drive input and output (disk I/O) resources used for the
HSTC’s jobs (e.g., offloading disk to tape). Both job I/O resources and host I/O resources
draw from the same disk I/O resources. Thus, one impacts the other’s performance. You
can use the “Host vs. job I/O policy” setting to determine the priority of host I/O relative to
job I/O.
HSTC’s jobs (e.g., offloading disk to tape). Both job I/O resources and host I/O resources
draw from the same disk I/O resources. Thus, one impacts the other’s performance. You
can use the “Host vs. job I/O policy” setting to determine the priority of host I/O relative to
job I/O.
Logical Disk – A number of areas on one or more disk drives that the computer system
considers as one filesystem. The areas of disk space are not necessarily contiguous but
are presented to the computer system as a single disk drive. In disk arrays, drives are
presented as individual logical disks (See “JBOD”) or are configured by a RAID controller
as logical disks spanning multiple disks (See “RAID”).
considers as one filesystem. The areas of disk space are not necessarily contiguous but
are presented to the computer system as a single disk drive. In disk arrays, drives are
presented as individual logical disks (See “JBOD”) or are configured by a RAID controller
as logical disks spanning multiple disks (See “RAID”).
LVD – Low Voltage Differential (LVD) uses less power than the HVD bus, is less expen-
sive and allows the higher speeds of Ultra 2/3 SCSI. LVD terminators run on 3.3 Volts
DC.
sive and allows the higher speeds of Ultra 2/3 SCSI. LVD terminators run on 3.3 Volts
DC.
Media changer – A mechanical device within a tape library that moves tapes to an inter-
nal tape drive. A media changer allows the library to load tapes sequentially into a tape
drive during a write/read operation requiring multiple tapes. The media changer device
usually has its own SCSI ID and resides on LUN 0 of that ID.
nal tape drive. A media changer allows the library to load tapes sequentially into a tape
drive during a write/read operation requiring multiple tapes. The media changer device
usually has its own SCSI ID and resides on LUN 0 of that ID.
MTU
Maximum Transmission Unit (MTU) is the maximum packet size, in bytes, that can be
transmitted across a link. Changing the default packet size from an MTU size of 1,500 to
9,000 (also called a “jumbo” packet) can significantly increase performance depending
upon the activity. For this to be effective, however, each point in the network must be con-
figured to support jumbo packets. If much of the network is dedicated to 10/100 Mbps
Ethernet, the MTU packet size ought to be set to 1,500 to minimize layer-two fragmenta-
tion and reassembly.
Maximum Transmission Unit (MTU) is the maximum packet size, in bytes, that can be
transmitted across a link. Changing the default packet size from an MTU size of 1,500 to
9,000 (also called a “jumbo” packet) can significantly increase performance depending
upon the activity. For this to be effective, however, each point in the network must be con-
figured to support jumbo packets. If much of the network is dedicated to 10/100 Mbps
Ethernet, the MTU packet size ought to be set to 1,500 to minimize layer-two fragmenta-
tion and reassembly.
Optical Ethernet – Ethernet consisting of optical fiber cabling. The miSAN-V-Series Opti-
cal Fiber interface requires a dual mode optical fiber cable having an SC duplex connec-
tor.
cal Fiber interface requires a dual mode optical fiber cable having an SC duplex connec-
tor.