Transcript 1.2 Storage Devices

CompTIA Server+ Certification
(Exam SK0-004)
1.2 Storage Devices
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Objectives
• Describe the features and
performance
characteristics of serverclass hard disks and solid
state drives
• Describe features of the
SCSI interface and know
how to configure devices
correctly
• Describe features of the
SATA and SAS interfaces
and know how to configure
devices correctly
1.2 Storage Devices
15
Mass Storage Devices
• Persistent storage – can preserve data without
power source
• Application installation and data files
• Shared disk resource
• Interfaces - SCSI / SAS / SATA
• Drive form factors
o
3.5”
o
2.5”
o
5.25”
o
Height – half height or low profile
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Hard Disk Drive (HDD)
• Platters, tracks, sectors, and
cylinders
• Advanced Format / 4K
• Revolutions per Minute (rpm)
o
15,000
o
10,000
o
7200 / 5400
• Access time (milliseconds / ms)
o
Seek time
o
Rotational latency
• Internal transfer rate
• External transfer rate
• Capacity (Gigabytes / GB) or
Terabytes (TB)
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Enclosure / Backplane
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SCSI
• Small Computer System Interface (SCSI)
• Parallel SCSI
o
SCSI-1
o
SCSI-2
− Fast / wide SCSI
− Active termination
o
SCSI-3
− UltraSCSI
− Firewire
− Fiber Channel / iSCSI
− SAS
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Parallel SCSI Configuration
• HBA (Host Bus Adapter)
• Signaling
o
o
o
Low Voltage Differential
(LVD)
Single Ended (SE)
High Voltage Differential
(HVD)
• Termination
• IDs and LUN (Logical
Unit Number)
• Drivers / config utility
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Parallel SCSI Connectors
• IDC50 - a 50-pin internal connector used with early
SCSI devices (SCSI-1)
• CN50 - a 50-pin Centronics-style connector used for
external connections in early SCSI devices
• HD68 - 68-pin connectors used for internal and
external ports. 68-pin adapters support Wide SCSI
• Single Connector Attachment (SCA) - an 80-pin
connector that incorporates both a power connector
and configuration wires, allowing for hot swappable
drives
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SAS
• Serial Attached SCSI
(SAS)
• Dominates enterprise
server market
• 3, 6, or 12 Gbps
• Bus can host SATA
devices
• Configuration
o
Dual port (redundancy)
o
Single- versus multi-lane
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SAS Connectors
• SFF 8087 - internal mini connector for both adapter card
("host") and 4 drive or backplane ports ("target")
• SFF 8088 - external mini connector for both adapter card and
drive enclosures
• SFF 8484 ("Multilane") - legacy 32-pin internal or external
HD connector (host) supporting four 7-pin lanes (target). The
remaining pins are used for "sideband" signals (LEDs and
status monitoring)
• SFF 8470 ("Infiniband") - legacy jackscrew connector for
both internal and external use
• SFF 8482 - internal connector compatible with both SAS and
SATA drives. This type of connector would be used principally
to attach SATA devices (such as DVD drives) to an SAS bus
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SATA
• Serial ATA (SATA)
• Desktop market /
cheaper servers
• 1.5 / 3 / 6 Gbps
• eSATA
• SATA and SAS
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Solid State Drive (SSD)
• Drive using flash memory
for solid state storage
o
o
Single Level Cell (SLC
Multi-Level Cell (MLC) /
Enterprise MLC (eMLC)
• SSD interfaces
o
SATA
o
PCIe (PCI Express)
o
SATAe (SATA Express)
o
Advanced Host Controller
Interface (AHCI) versus NonVolatile Memory Host Controller
Interface Specification (NVMHCI)
/ NVM Express (NVMe)
HP SSD with SATA interface (Image © 2014 HewlettPackard Development Company)
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SSD Performance
• Use profile
o
Reads versus writes
o
Sequential versus random I/O
• Input / Output Operations per Second (IOPS)
• Wear leveling
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Review
• Describe the features and
performance characteristics
of server-class hard disks
and solid state drives
• Describe features of the
SCSI interface and know
how to configure devices
correctly
• Describe features of the
SATA and SAS interfaces
and know how to configure
devices correctly
1.2 Storage Devices
26