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Chapter 6 – Managing Disk and Data Storage

Chapter 6 – Managing Disk and Data Storage. MIS 431 Created Spring 2006. Data Management Concepts. Basic Disks – traditional disk mgt techniques Default choice when WS03 installed Format with FAT, FAT32, or NTFS

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Chapter 6 – Managing Disk and Data Storage

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

  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) MIS 431 Chapter 6

  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 0=no redundancy; RAID 5=full redundancy MIS 431 Chapter 6

  4. Data Management Concepts, contd • Dynamic Disk – doesn’t 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 MIS 431 Chapter 6

  5. Dynamic Disks Cautions • Caution! • Don’t 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! MIS 431 Chapter 6

  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!! MIS 431 Chapter 6

  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 < 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. MIS 431 Chapter 6

  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. MIS 431 Chapter 6

  9. Disk Management tool MIS 431 Chapter 6

  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 MIS 431 Chapter 6

  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 MIS 431 Chapter 6

  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 MIS 431 Chapter 6

  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! MIS 431 Chapter 6

  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 MIS 431 Chapter 6

  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 MIS 431 Chapter 6

  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) MIS 431 Chapter 6

  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. MIS 431 Chapter 6

  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) MIS 431 Chapter 6

  19. Disk Utilities • Disk Defragmenter – reduces fragmentation, where files are not stored in contiguous blocks. Makes access faster but doesn’t save space. • Advice: defragment monthly or more on busy servers • Access – in Disk Management, click Disk Defragmenter in left pane. Fig 6-18 MIS 431 Chapter 6

  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! MIS 431 Chapter 6

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