Table of Contents
Advertisement
The inclusion of extra components of a given type in a
system (beyond those the system requires to carry out its
functions).
S
SAF-TE
SCSI Accessed Fault-Tolerant Enclosure, an "open"
specification designed to provide a comprehensive
standardized method to monitor and report status
information on the condition of disk drives, power
supplies, and cooling systems used in high availability
LAN servers and storage subsystems. The specification is
independent of hardware I/O cabling, operating systems,
server platforms, and RAID implementation because the
enclosure itself is treated as simply another device on the
SCSI bus. Many other leading server, storage, and RAID
controller manufacturers worldwide have endorsed the
SAF-TE specification. Products compliant with the SAF-
TE specification will reduce the cost of managing storage
enclosures, making it easier for a LAN administrator to
obtain base-level fault-tolerant alert notification and status
information.
SCSI
Small Computer System Interface, a technological standard
that defines connections between computers and peripheral
devices.
SCSI Adapters
Storage controllers for managing SCSI devices.
SCSI Drive
A disk drive equipped with a SCSI interface (sometimes
referred to as a SCSI Disk). Each disk drive will be
assigned a SCSI address (or SCSI ID), which is a number
from 0 to 7 (0 to 15 under wide or Ultra SCSI). The SCSI
address uniquely identifies the drive on the SCSI bus or
channel.
Sector
The unit in which data is physically stored and protected
against errors on a fixed-block architecture disk.
Sequential I/O
232
A type of read and write operation where entire blocks of
data are accessed one after another in sequence, as opposed
to randomly.
Server
A computer program that provides and manages services to
other computer programs on the same or other computers.
The computer that a server program runs in is also
frequently referred to as a server.
SES
SCSI Enclosure Services, a standard for SCSI access to
services within an enclosure containing one or more SCSI
devices. For disk drives, power supplies, cooling elements,
and temperature sensors, the actions performed are the
same as for SAF-TE monitoring. If a UPS is connected to
any SES-monitored enclosures, and an AC failure or two
minute warning is reported, conservative cache is enabled
and all system drives are switched to write-through cache.
Primarily used in fibre enclosures.
Session
The period of time between any two consecutive system
shutdowns; system shutdown may be either a power off/on,
or a hardware reset.
Standard Disk Drive
This term refers to a hard disk drive with SCSI, IDE, or
other interface, attached to the host system through a
standard disk controller.
Standby Replacement of Disks
See also Hot Spare. One of the most important features the
RAID controller provides to achieve automatic, non-stop
service with a high degree of fault-tolerance. The controller
automatically carries out the rebuild operation when a
SCSI disk drive fails and both of the following conditions
are true: • A "standby" SCSI disk drive of identical size is
found attached to the same controller; • All of the system
drives that are dependent on the failed disk are redundant
system drives, e.g., RAID 1, RAID 3, RAID 5, and RAID
0+1. Note: The standby rebuild will only happen on the
SAME DAC960 controller, never across DAC960
controllers. During the automatic rebuild process, system
activity continues as normal. System performance may
degrade slightly during the rebuild process. To use the
standby rebuild feature, you should always maintain a
standby SCSI disk in your system. When a disk fails, the
Spheras Storage Director Installation & User Guide
Advertisement
Table of Contents
