Transcript Windows Server 2008

Guide to Operating Systems,
4th ed.
Chapter 7: Using and Configuring
Storage Devices
Objectives
•
•
•
•
•
•
Explain common disk storage technologies
Back up data using operating system tools
Explain network storage technologies
Discuss removable disk storage
Describe tape drive technologies
Explain storage management tools in different
operating systems
Guide to Operating Systems, 4th ed.
2
Disk Storage Options
• Today, most computers come with one or more
DVD/CD-ROM drives and a fixed hard drive
• Removable hard drives and flash drives can be
connected through USB ports and other
communication channels
• “Disk” refers to a hard drive and “disc” refers to an
optical medium, such as a CD or DVD
Guide to Operating Systems, 4th ed.
3
Disk Storage Options
Guide to Operating Systems, 4th ed.
4
Hard Drive Interfaces
• In some older PCs, a popular hard drive interface
was the Integrated Drive Electronics (IDE) interface
• Enhanced IDE (EIDE) – supports higher transfer
speeds, connects up to four devices, and is found
in older PCs
– American National Standards Institute (ANSI) – refers to the
IDE standard as the Advanced Technology Attachment (ATA)
• The newer high-speed serial version of the ATA
interface is called Serial ATA (SATA)
• External SATA (eSATA) – interface that enables
connectivity for an external SATA drive
Guide to Operating Systems, 4th ed.
5
Hard Drive Interfaces
• Through eSATA you can connect external SATA
drives by plugging into a port or slot interface
– Interface options include PCMCIA and Express Card
• Light Peak – an emerging technology that is
projected to be a contender for the USB peripheral
device market (uses an optical connection)
• Small Computer System Interface (SCSI) –
relatively fast interface that can support up to 8 or
16 devices
– Disks and other SCSI devices are connected together in a
daisy chain fashion
Guide to Operating Systems, 4th ed.
6
Hard Drive Interfaces
• SCSI (continued)
– Each end of the SCSI cable must be electrically terminated to
prevent echoes and ghost signals on the cable
– A terminator is an electronic resistor that absorbs the signal
• Can be built into a device, such as a disk drive
– Advances in SCSI have resulted in several enhancements:
Ultra SCSI, Ultra wide SCSI, Ultra2 SCSI, Ultra2 wide SCSI,
Ultra3 SCSI (Ultra 160), Ultra320 SCSI, and Ultra640 SCSI
• Ultra640 transfers at a rate of 640 MBps, has a 16-bit bus, handles
16 devices and used for servers and network storage
– Serial Attached SCSI (SAS) – new technology that supports up
to 16,256 devices, has initial speeds in the 3-6 Gbps range,
and is compatible with the SATA interface
Guide to Operating Systems, 4th ed.
7
Hard Drive Interfaces
SCSI Configuration
Guide to Operating Systems, 4th ed.
8
Hard Drive Interfaces
• Globally Unique Identifier (GUID) Partition Table
or GPT – a new way to partition disks
– Allows OSs to handle extremely large disks
• Windows System Information utility is a way to view
the hard drive configuration on your computer
• Hard disk failures do happen so backing up your
computer is an essential practice
• Most OSs today offer Backup utilities that make
backing up data easier
– Examples of those utilities are listed in the table on the next
slide
Guide to Operating Systems, 4th ed.
9
Hard Drive Interfaces
Backup utilities
Guide to Operating Systems, 4th ed.
10
Hard Drive Interfaces
• Basic and Dynamic Disks – Windows OS has the ability
to distinguish between these two disk types
– Basic – a physical hard drive that contains primary and
extended partitions, or logical drives that are known as volumes
– Dynamic – volumes that can span multiple disks
• Fault tolerance is supported – involves implementing software or
hardware to protect against hardware failures, power interruptions,
and lost data
• Supported by all editions of Windows Server 2003/R2 and
Windows Server 2008/R2
• Supported by some later versions of Windows desktop versions
• Basic disks can be converted to dynamic disks by using the Disk
Management tool in Windows
Guide to Operating Systems, 4th ed.
11
Hard Drive Interfaces
• Solid State Drives (SSD) – a storage technology
that uses semiconductors for storage
– Similar technology is used in flash drives but SSDs are larger
than flash drives and hold more data
• Advantages of SSD over traditional hard drives:
–
–
–
–
–
No moving parts
No sensitive magnetic disks
Faster access to data
More reliable because there are no fragile drive platters
Lower power requirements because there is no motor
• Disadvantage:
– More expensive than traditional hard disk storage
Guide to Operating Systems, 4th ed.
12
Hard Drive Interfaces
• RAID Arrays – Redundant array of inexpensive (or
independent) disks
• RAID arrays serve four purposes:
–
–
–
–
Increased reliability
Increased storage capacity
Increased speed
Fault tolerance
• Various RAID designs, typically designated as
Level 0 – Level 5
• RAID can be costly and is primarily used on
servers
Guide to Operating Systems, 4th ed.
13
Hard Drive Interfaces
• RAID is implemented as a combination of hardware
and software
– Hardware – hard disks connected to a controller (or more than
one)
– Software – provides an interface to the OS to provide access to
special RAID features offered
• Modern RAID systems offer configuration at the
hardware level (does not need OS to configure
RAID)
• RAID is covered in more detail in Chapter 11
Guide to Operating Systems, 4th ed.
14
CD, DVD, and Blu-Ray
• Compact Disc (CD) Technology – a polycarbonate
plastic disc that has a reflective optical surface that
can be read by a laser
• CD-ROM – compact disc read-only memory uses a
technology in which information is pressed onto the
disc one time (read or played many times)
• CD-R – compact disc recordable – information can
be burned onto the disc by a laser one time
– Commonly called “burning a disc”
• CD-RW – compact disc rewriteable – you can write
to the disc many times
Guide to Operating Systems, 4th ed.
15
CD, DVD, and Blu-Ray
• CDs store data in a big “spiral” instead of tracks and
sectors like hard disks
• When a disc is read:
– Laser light is emitted by the CD-ROM drive head and reflected
off the disc surface onto an optical pickup
– Surface is covered with indentations or “pits”, depending on the
size of the pits, ones or zeros are returned
– The surface of the CD reflects light during a data read
operation
• CDs are very sensitive to scratches and other kinds
of damages that can hinder optical readout
Guide to Operating Systems, 4th ed.
16
CD, DVD, and Blu-Ray
• Data on the CD can employ any or all of the
following error recovery methods:
– Parity – simple error detection method that typically counts the
number of nonzero bits in a string of data, then sets a parity bit
to reflect whether the bits total to an even or odd number
– Error correction code (ECC) – can replace errors by adding
duplicate data or parity data so missing data can be recovered
– Error concealment – uses surrounding data to help calculate
approximate data to fill in for the missing data
– Cyclic redundancy check code (CRCC) – uses an algebraic
polynomial and error key to detect and overcome errors
– Reed-Solomon R-S codes – uses a complex polynomial
technique for addressing data errors
Guide to Operating Systems, 4th ed.
17
CD, DVD, and Blu-Ray
• A standard CD holds 737 MB of user data, but
counting space for error detection the true storage
capacity is about 847 MB
• CDs are rated in terms of recording minutes as well
as megabytes of data because they are used for
music or audio as well as for data
• Rotational speeds of CD-ROM drives range from
the normal speed of 200-500 revolutions per
minute to as high as 72 times that speed (72X)
Guide to Operating Systems, 4th ed.
18
CD, DVD, and Blu-Ray
• Digital video disc (DVD) – works a lot like a CD but
storage capacity and data transfer rate of a DVD
are much higher than for a CD
• DVDs can store information on two sides with up to
two layers per side
– Unlike CDs, DVDs have a second layer that is read by using
light that hits the disk at a different angle
• A single-layer single-sided DVD holds 4.7 GB of
data
– A double-layer single-sided DVD holds 8.54 GB and a doublelayer double-sided DVD holds up to 17.08 GB of data
Guide to Operating Systems, 4th ed.
19
CD, DVD, and Blu-Ray
• Recordable and Rewritable DVDs
– Digital video disc-recordable (DVD-R)
– Digital video disc+recordable (DVD+R)
Guide to Operating Systems, 4th ed.
20
CD, DVD, and Blu-Ray
DVD drives and media
Guide to Operating Systems, 4th ed.
21
CD, DVD, and Blu-Ray
• DVD/CD-ROM Drives
– Usually connected to a computer using a hard disk
interface
– Most PCs use the SATA, EIDE, or SCSI interface
– Require different drivers than hard disk drives
– Most PCs have drivers built into the BIOS system and
boot system
• This enables computers to boot an OS from a CD or DVD
– Most PCs can boot an OS directly from a CD or DVD for
initial installation
Guide to Operating Systems, 4th ed.
22
CD, DVD, and Blu-Ray
• Blu-Ray Drives
– Blu-ray discs are different from DVD/CD-ROM because the
data is recorded on top of the polycarbonate layer
• Enables the information on the disc to be read more accurately
without the problem of “disc tilt”
– Data transfer speed can reach 36 MBps (compared to about 10
MBps for DVDs)
– Current storage capacity of a disc is a maximum of 50 GB
– Connected to computers using a SATA interface
– To play a Blu-ray video on a computer, you must have a video
display compatible with High-bandwidth Definition Content
Protection (HDCP)
Guide to Operating Systems, 4th ed.
23
Network Storage and Cloud Storage
• Organizations today are dealing with massive
amounts of data
– Backups, disaster recovery, and availability of data are reasons
why storage area networks and cloud storage are growing in
popularity
• Storage Area Networks (SAN) – a grouping of
storage devices that form a small private network
– Data transfer between servers and storage systems takes
place on Fibre Channel
– Typical speed for most Fibre Channel’s is 8 Gbps (16 and 40
Gbps under development)
Guide to Operating Systems, 4th ed.
24
Network Storage and Cloud Storage
Storage area network (SAN)
Guide to Operating Systems, 4th ed.
25
Network Storage and Cloud Storage
• InfiniBand – designed for ultrafast connectivity in
data centers, such as linking servers for clustering
to act as one powerful server
– Emerged as an alternative to Fibre Channel
• Network attached storage (NAS) – a way to directly
attach storage to a local area network (LAN)
– Works with multiple OSs
– Allows most clients to access the storage on the network using
TCP/IP (standard network communications protocol)
– Different than a SAN – servers communicate with the storage
over the main network rather than by a separate Fibre Channel
Guide to Operating Systems, 4th ed.
26
Network Storage and Cloud Storage
• NAS can use Internet Small Computer System
Interface (iSCSI) for communications
– Offers TCP/IP-based communication that enables connectivity
with SCSI-based storage arrays
– Faster data access than Fibre Channel because data
transmission speeds are linked to the actual speed of the
network
– Because it uses TCP/IP, can be used on LANs, WANs, or over
the Internet
– Disadvantage: creates extra network traffic which can lead to
network congestion
Guide to Operating Systems, 4th ed.
27
Network Storage and Cloud Storage
Network attached storage (NAS)
Guide to Operating Systems, 4th ed.
28
Network Storage and Cloud Storage
• Cloud Storage – available through the Internet or
through Web-based applications
– Data may be transferred over the Internet or network to the
user’s computer or user can manipulate data on a remote
computer via the Internet
– User’s data is available from any location where Internet is
available
– Provides fault tolerance
– Examples: YouTube hosts millions of video files, Google Docs
stores document files and spreadsheets
– Files can be made public or kept private
Guide to Operating Systems, 4th ed.
29
Removable Disks
• Early examples were floppy disks and Zip disks
– Storage capacities from 1.44 MB – 750 MB
• Today, users expect removable storage capacities
to match hard disk capacities
– Some removable hard disks that connect to USB ports can hold
over 1 TB of data
• Another removable disk option: SSD
– Connects to the computer through a USB port
• Other options:
– eSATA and Light Peak (mentioned earlier in this chapter)
Guide to Operating Systems, 4th ed.
30
USB Flash Drives
• Flash drives or thumb drives – plug into a USB port
and have no internal moving parts
– Don’t require additional drivers and are quickly recognized by
PnP
– Easy to use and fit in your pocket
– Typical sizes (at this writing) include 4, 8, 16, 32, and 64 GB
– Work with Windows, UNIX/Linux, and Mac OS X
Guide to Operating Systems, 4th ed.
31
USB Flash Drives
Storage media capacities and life spans
Guide to Operating Systems, 4th ed.
32
Tapes and Tape Drives
• Tape backup systems are a traditional choice for
backing up large amounts of data
• Use magnetic storage and record data in
sequential order
– Disadvantage – to find a file near the end of the tape, drive
must first go through all of the data recorded prior to that file
– Access to data is typically slower than a removable hard drive
• Most popular for long-term storage
– With disk drives growing into terabytes, tape drive technology is
continuing to evolve in order to keep up
Guide to Operating Systems, 4th ed.
33
Tapes and Tape Drives
Tape media capacities
Guide to Operating Systems, 4th ed.
34
Tapes and Tape Drives
• DAT Drives - Digital audio tape
– Use a 4-mm tape and the digital data storage (DDS) format
– DDS-1 has a capacity of 2 GB (4 GB compressed)
– Current standard is DDS-5 – storage capacity of 36 GB (72 GB
compressed)
– Backward compatible – can upgrade to a DDS-5 drive and still
read DDS-4 tapes
– Rated at an archival life of 10 years
– Still used for audio recordings, but use for data storage is
mostly replaced by other tape technologies
Guide to Operating Systems, 4th ed.
35
Tapes and Tape Drives
• DLT Drives – Digital linear tape
– Use half-inch wide magnetic tapes
– Record data in tracks
– Offers a high-speed search capability – a file can be found in a
few seconds to a little over a minute
– Used in many automated tape backup systems
• SDLT Drives – Super digital linear tape
– Use both magnetic and optical recording methods
– Laser technology can more accurately write data to the tape
and allows for greater density of information
• Up to 2.4 TB compressed
• Both DLT and SDLT have an archival life of up to
30 years
Guide to Operating Systems, 4th ed.
36
Tapes and Tape Drives
• AIT Drives – Advanced intelligent tape (AIT)
– First introduced in 1996 and used mainly in midrange servers
– Tapes have an erasable memory chip inside the cartridge that
stores information normally written at the beginning of the tape
• Can fast forward and pinpoint information faster
– Started out with a capacity of 35/90 GB
• S-AIT Drives – Super advanced intelligent tape
– Has a capacity of 500 GB/1.3 TB (native/compressed)
• Both of these drives can sustain up to 30,000 tape
passes and have an archival life of 30 years
Guide to Operating Systems, 4th ed.
37
Tapes and Tape Drives
• LTO Drives – Linear tape open
– Most widely accepted in high-end servers (because of highspeed performance)
– Standards are open to the public and are nonproprietary
– LTO Ultrium format was developed so that LTO tapes can be
used in existing DLT tape drives
• For faster conversion to LTO Ultrium technology
– Offer fast data transfer speed of up to 240 MBps, for
noncompressed data and 120 MBps for compressed data
– Can sustain up to 260 tape passes and have an archival life of
15-30 years
Guide to Operating Systems, 4th ed.
38
Storage Management Tools
• Windows Storage Management Tools
– Windows Disk Management tool for hard drive and removable
storage is available in the following versions:
• Windows XP/Vista/7, Server 2003/R2, and Server 2008/R2
– Enables you to:
• Create, format, and delete partitions
• Manage partitions
• Manage removable storage such as hard drives, DVD/CD-ROM
drives, and flash drives
• Convert a basic disk to a dynamic disk
– Can access this tool from Computer Manager
– Other utilities are Disk Defragmenter, chkdsk, and format
Guide to Operating Systems, 4th ed.
39
Storage Management Tools
Windows Disk Management tool in Windows 7
Guide to Operating Systems, 4th ed.
40
Storage Management Tools
• Disk Management Tools in UNIX/Linux
– Common command-line utilitities: fdisk, format, sfdisk, and
cfdisk
– sfdisk and cfdisk enable you to verify partitions, list information
about partitions, and repartition a disk
– Command-line utility mount – mounts a file system so that you
can use a disk partition
• Many need to manually mount file systems for DVD/CD-ROM or
flash drives
– In Linux with the GNOME desktop, there are GUI tools to
manage disk storage
Guide to Operating Systems, 4th ed.
41
Storage Management Tools
GNOME Disk Utility
Guide to Operating Systems, 4th ed.
42
Storage Management Tools
Summary of UNIX/Linux disk management
commands
Guide to Operating Systems, 4th ed.
43
Storage Management Tools
• Mac OS X Disk Utility – available to partition,
format, and manage hard drives, DVD/CD-ROM
drives, removable hard drives, flash drives, and
other storage
– Options available depend on the type of storage medium
selected
• When you select a storage medium in the left pane, the utility
displays appropriate tabs for the actions you can perform on that
storage medium
• Because Mac OS X is UNIX-based, you can also
open a terminal window and use the mount
command to manage storage media
Guide to Operating Systems, 4th ed.
44
Storage Management Tools
Mac OS X Snow Leopard Disk Utility
Guide to Operating Systems, 4th ed.
45
Chapter Summary
• This chapter provides an introduction to how OSs interface with
storage devices and gives an overview of storage device
technologies
• Popular computer storage technologies include hard disk drives,
solid state drives, RAID arrays, CD, DVD, and Blue-Ray
technologies that interface to the computer through the OS and
device drivers
• An important part of learning to manage hard disk storage is
performing backups
• Network storage devices include storage area networks (SANs)
and network attached storage (NAS)
• Cloud storage enables users to access storage through the
Internet or a network using Web-based interfaces
Guide to Operating Systems, 4th ed.
46
Chapter Summary
• SANs can use Fibre Channel or InfinitBand technology and
NAS can use iSCSI storage technology
• Modern medium- to large-capacity removable storage
includes USB attached removable hard drives, USB solid
state drives, eSATA drives, Light Peak drives, and USB flash
drives
• Common tape storage options include DAT, DLT, SDLT,
AIT, S-AIT, and LTO tapes and drives
• Operating systems come with storage management tools,
such as the Windows Disk Management tool, the Disk Utility
in GNOME for Linux, and the Mac OS X Disk Utility
Guide to Operating Systems, 4th ed.
47