1. MIS 431 Chapter 61 Chapter 6 – Managing Disk and Data Storage MIS 431 Created Spring 2006

2. MIS 431 Chapter 62 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. MIS 431 Chapter 63 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

4. MIS 431 Chapter 64 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

5. MIS 431 Chapter 65 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!

6. MIS 431 Chapter 66 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. MIS 431 Chapter 67 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.

8. MIS 431 Chapter 68 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. MIS 431 Chapter 69 Disk Management tool

10. MIS 431 Chapter 610 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. MIS 431 Chapter 611 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. MIS 431 Chapter 612 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. MIS 431 Chapter 613 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. MIS 431 Chapter 614 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. MIS 431 Chapter 615 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. MIS 431 Chapter 616 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. MIS 431 Chapter 617 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. MIS 431 Chapter 618 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. MIS 431 Chapter 619 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

20. MIS 431 Chapter 620 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!