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Chapter 6

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... removable disks, detachable disks (like USB flash drives), or to shared SCSI bus. ... by requiring fewer seeks all drives can be written simultaneously. ... – PowerPoint PPT presentation

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Title: Chapter 6


1
Chapter 6 Managing Disk and Data Storage
  • MIS 431 Created Spring 2006

2
Data Management Concepts
  • Basic Disks traditional disk mgt techniques
  • Default choice when WS03 installed
  • Format with FAT, FAT32, or NTFS
  • Only one partition is the active partition (aka
    system partition) where the boot files are found
    typically C
  • Partition type
  • Primary at least one is required, max of 4/disk
  • Extended lets you exceed 4 primary partition
    limit can have multiple logical drives (Fig 6-2)

3
Data Management Concepts, contd
  • Basic Disks, contd
  • Volume set two or more drives combined to look
    like one volume with a single drive letter
  • Stripe set two or more drives combined like a
    volume set but striped for RAID 0 or RAID 5.
  • Stripe concept means that a block is contained in
    more than one drive for faster access than if on
    a single drive.
  • RAID 0no redundancy RAID 5full redundancy

4
Data Management Concepts, contd
  • Dynamic Disk doesnt follow traditional
    partitioning methods
  • Can set up a large number of volumes on one disk
    and the ability to extend volumes onto additional
    hard drives if out of space. Reasons
  • Extend NTFS volumes
  • Configure RAID volumes for fault tolerance or
    increased performance
  • Reactivate missing or offline disks
  • Changes disk settings without having to restart
    the server

5
Dynamic Disks Cautions
  • Caution!
  • Dont convert basic disks to dynamic disks if the
    server is configured to dual boot to other
    operating systems.
  • Dynamic disks are not supported on portable
    computers, removable disks, detachable disks
    (like USB flash drives), or to shared SCSI bus.
  • Simple Volume dedicated and formatted portion
    of disk space on a dynamic disk.
  • Can later extend the volume by allocating a
    portion of the unallocated space.
  • Only simple volumes with NTFS can be extended
  • Neither the system nor boot volume in WS03 can be
    extended!

6
Dynamic Disks, contd.
  • Spanned Volume space in between 2 and 32
    dynamic disks that is treated as a single logical
    volume.
  • Example 4 smaller volumes of various sizes are
    combined into a single 11 GB spanned volume with
    its own drive letter, reducing the number of
    drive letters needed. See Fig 6-3 p221.
  • Disadvantage if ANY of the spanned disks fail,
    the entire spanned volume fails!!

7
Dynamic Disks, contd.
  • WS03 Striped Volume RAID level 0
  • Can extend the life of a hard drive by spreading
    data equally over 2 or more disks
  • Increases disk performance by requiring fewer
    seeks all drives can be written simultaneously.
  • In WS03 striping requires at least 2 and up to 32
    physical disks the aggregation of striped disks
    is a striped volume.
  • Data is written in 64KB blocks so especially good
    for large databases (not good for small files lt
    64KB)
  • Data can be lost when a disk is lost therefore
    many choose RAID 5 instead with redundancy.
  • Some choose hardware RAID instead of WS03 only
    for better performance and automatic rebuilding
    on failure.

8
Managing Partitions and Volumes
  • Disk Management MMC is cool! (Fig 6-5)
  • Can add to a custom MMC or go through the Storage
    section in the Computer Management tool.
  • Functions create, delete, manage disks,
    partitions and volumes.
  • Also provides information about disks,
    partitions, and volumes that previously you
    needed a special tool to access.

9
Disk Management tool
10
Disk Management tool
  • Rt-click a partition or volume and click
    Properties from Disk Management (Fig 6-6)
  • Can rt-click a partition and click Properties
    from within Windows Explorer and get to the same
    screen
  • Tabs General, Tools, Hardware, Sharing,
    Security, Shadow Copies, Quota (but may vary
    depending if you have installed other tools on
    your server)
  • Activities
  • 6-1 Viewing Disk Properties
  • 6-2 Create/Delete Primary Partition
  • 6-3 Create Extended Partition
  • 6-4 Create Logical Drive
  • 6-5 Convert Basic Disk to Dynamic Disk
  • 6-6 Create Simple Volume
  • 6-7 Extend a Volume using DISKPART

11
Mounted Drives
  • Make a drive appear as a folder instead of as a
    drive letter (good if you are out of drive
    letters)
  • Only an empty folder on a NTFS volume can be used
    for mounting a drive
  • Activity 6-8 Mount an NTFS Volume

12
Fault Tolerant Disk Strategies
  • FT systems will gracefully recover from HW or
    SW failure more or less automatically.
  • WS03 offers software RAID as well as the backup
    service.
  • RAID Redundant Array of Inexpensive Disks

13
RAID (supported by WS03)
  • Level 0 striping only, no FT!
  • Level 1 disk mirroring where an identical disk
    is written at the same time as the primary disk
    (Fig 6-9)
  • Level 2 striping plus error correction
  • Level 3 like level 2 but error correction
    information is written to one drive only
  • Level 4 similar to level 2
  • Level 5 includes striping, error correction,
    and checksum verification (see next page) and
    allows automatic recovery from lost disk!

14
More RAID 5
  • Uses 3-for-2 concept need three identical
    disks to provide storage equivalent to 2
  • When a disk fails in RAID 5, all redundancy is
    lost but the system continues to operate normally
  • Hot swap drives are preferred can be replaced
    in real time while server is running
  • When the disk is replaced, the system will begin
    to rebuild the extra information in the
    background to reach full redundancy point

15
More RAID 5
  • Hardware RAID is generally preferred but costs
    more than using WS03 (built-in). TCO must be
    considered ?
  • HW RAID controller card communicates directly
    with the drive and serves as the disk controller
    card typically SCSI
  • 500 and 1500 price points from Dell
  • See list on p. 240 for benefits

16
Monitor Disk Health
  • Disk Management provides info on health of disks
    and volumes
  • Messages for volumes
  • Failed make sure disk is connected to system
  • Failed Redundancy RAID 5 is unavailable or
    mirrored volume is unavailable
  • Formatting temp status while formatting volume
  • Healthy volume is functioning normally
  • Regenerating missing disk in RAID 5 volume is
    reactivated and is generating its data.
  • Resyncing mirrored volume is synchronizing
    information with primary drive.
  • Unknown boot sector for volume is corrupted and
    data is not accessible (BAD)

17
Monitor Disk Health, contd.
  • Status messages for a disk
  • Audio CD an audio CD is in the CD or DVD
  • Foreign disk is a dynamic disk imported from
    another computer. Rt-click Import foreign disk.
  • Initializing temp status while basic disk is
    being converted to a dynamic disk.
  • Missing disk has been removed or corrupted
  • No Media CD/DVD drive is empty
  • Not Initialized new disk added to system
    without valid disk signature. Should initialize
    it.
  • Online normal.
  • Online (errors) I/O errors detected on dynamic
    disk. Check Disk
  • Offline disk no longer accessible
  • Unreadable I/O errors or corruption on part of
    disk. Rescan Disks.

18
Other Disk Maint./Mgt. Utilities
  • Check Disk scans disk for bad sectors and file
    system errors
  • Access in disk Properties Tools (Fig 6-13,14)
  • Can use CHKDSK at command prompt (Fig 6-15)
  • Convert convert FAT/FAT32 to NTFS
  • Disk Cleanup removes recycle bin files,
    compresses old files, deletes temporary files
  • Access in disk Properties General tab (Fig
    6-16)

19
Disk Utilities
  • Disk Defragmenter reduces fragmentation, where
    files are not stored in contiguous blocks. Makes
    access faster but doesnt save space.
  • Advice defragment monthly or more on busy
    servers
  • Access in Disk Management, click Disk
    Defragmenter in left pane. Fig 6-18

20
Disk Utilities from command line
  • DISKPART work with partitions active, assign
    drive letters, create/extend volumes and
    partitions
  • FORMAT you know this one!
  • FSUTIL controls advanced file settings
  • MOUNTVOL create, delete, or list volume mount
    points from command line but GUID is nasty to
    type in!
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