WINDOWS 2000 TE. Disk Management

Transcription

1 WINDOWS 2000 TE Disk Management

2 Introduction Server disks must be faster, more reliable and larger than the workstation based Counterparts. How to achieve this GOAL Spend more money for a drive with more of all the above mentioned features. Club a band of mediocre drives, acting in concert providing speed, capacity and fault tolerance, such a system is called RAID.

3 Windows 2000 Disk Storage Types Basic Storage Simple volume Dynamic Storage Striped volume C: D: -or- C: D: Primary partitions Spanned volume RAID-5 volume E: E: F: F: G: H: Extended partition with logical drives Mirrored volume

4 Disk Management Tool Create and delete partitions on a hard disk and make logical drives. Get status information concerning these items: The amount of free space left on disk for making partitions. Volume labels, their drive-letter assignment, file system type and size. Alter drive letter and file mounting assignments. Enlarge disk volumes. Create, delete, and repair mirror sets. Format any volume. Create and delete stripe sets and regenerate missing or failed members of stripe sets with parity.

5 SLED An acronym for single large expensive drive, SLED is a way of arranging your data on one very large, very (hopefully) reliable drive. SLED is a popular method of arranging data for tow reasons: It s simple. You only have to buy one disk and store your data on it. Dedicated RAID hardware has been expensive in the past. Even through it s not as expensive as it used to be, it still reflects an added cost. Trouble is, if that one very large and very reliable drive fails, then your data goes with it.

6 RAID Stands for Redundant Array of Independent Disks Provides reliability and performance by combining hard disks Note that RAID is not Redundant always e.g., RAID level 0 (Disk Stripping without Parity) is not fault tolerant as there is no redundant data to recreate the lost data. There are RAID level 0 to 10, providing different levels of reliability, performance and cost. Hardware based RAID is more expensive as compared to Software based RAID.

7 Basic Disks Basic disk is the kind of storage that NT has typically supported, allowing for primary and extended disk partitions and logical drives. Four-partition limit imposed by the structure of the disk partition table No support for new fault-tolerant volumes (ie., these disks don t support RAID)

8 Dynamic Disks Dynamic disks let you create, extend, and delete fault-tolerant and multi-disk volumes on-the-fly These disks support RAID. These disks lack of compatibility. They re incomprehensible in fact, invisible to any locally installed operating system other than Win2K

9 Conversions basic to dynamic Basic disks can be upgraded to dynamic disk. Dynamic disk can also be reverted back to Basic disk, provided they do not have any volumes.

10 Free and Unallocated Space Free space is an extended partition that doesn t yet have any logical drives in it, or the space within that partitions not yet divided into a logical drive. Unallocated space is space on a disk that is not part of a volume. It s not committed to be part of any volume or partition. Both basic and dynamic disks may have unallocated space.

11 Physical Disks A physical disk is that contraption of plastic and metal that you inserted in your server s case or have stacked up next to it. The Disk Management tool identifies physical drives by numbers (Disk 0, 1, 2...; CD 0, 1, 2,...) which cannot change. You cannot change the size of a physical disk. The size given to it when it was low level formatted is the size the drive will remain.

12 Partition or Volume In contrast to a physical disk, a partition or volume is a logical construct. A logical drive, primary partition, or anything else in the Disk Administrator that is assigned a drive letter or mounted to a path on an NTFS volume. One can change drive letter assignments and adjust the sizes of logical partitions, as they have no physical presence. A logical partition can be part or all of a physical disk or even (in the case of volume sets, and stripe sets) extend across more than one physical disk.

13 Note If there are number of hard disks of capacity more than One GB, then old BIOS can see only two of these drives one GB hard disk Once Win2K is up and running, however, it will see all of your hard disk. Computers with an up-to-date BIOS (something you should have for Y2K compliance anyway) generally won t have this problem. Any file system that Win2K supports; FAT FAT32, or NTFS, can format a partition smaller than 4GB (4096MB) with. For volumes larger than 4GB, you ll be limited to FAT32 or NTFS.

14 Mounted Drives Each logical disk volume is identified by a drive letter. Limited to a total of 26 letters for all local drives and mapped network connections. To get around this problem, Win2K supports mounting volumes to empty folders on NTFS volumes.

15 Mounted Drives Contd.. The basic idea of mounting a partition to a folder is that you re redirecting to the partition all read and write requests sent to that folder, even though the real drive X: is on a different physical disk entirely. You can mount a volume to as many paths as you like. The only restrictions are that the folders must be empty at the time of mounting and not mapped to any other volumes, and they must be on NTFS volumes on the local computer.

16 Mounted Drives Advantages You are not running out of drive letters for local and network partitions Enlarge a volume on a basic disk Create a fault tolerant area on a nonfault tolerant volume. These volume mappings are transparent to the user base.

17 Partitions Partition is a portion of a hard disk set up to act like a separate physical hard disk, rather than splitting a physical disk into several logical drives.

18 Primary Partitions A primary partition is a portion of a physical hard disk that the OS marks as bootable. Under DOS, only one partition Under Win2k, Win NT, Windows 9x, there can be multiple partitions One partition can be active at one time Primary Partition can not be broken into subpartitions You can create up to 4 partitions per disk You can have dual booting also, where one primary partition is running Win2K and other is running OS2.

19 Extended Partiton IF four logical partitions are not enough, one can create an Extended Partition from unallocated space on the disk There can be one extended partition on a disk. Before one can use an extended partition, it must be divided into one or more logical drives

20 Logical Drive It is a logical division of an extended partition that behaves like an entity. Extended partition can be divided into as many logical drives, provided each partition has the minimum required size Basic Disks support partitions and logical drives.

21 Volumes A volume is a logical division of unallocated space on a hard disk. It works like a logical drive or primary partitions except for the following Logical drive and primary partitions must be confined to a single disk And these can not be made larger Whereas Volumes may exist on one or more disks and more unallocated space can be added to them

22 Volumes contd.. Win2k support Simple volumes: which start out only taking uo space on one disk Spanned volumes: which start out taking up space on multiple disks Either of them can be extended.

23 Creating and Extending Spanned Disk 1 Dynamic 4094 MB Online Disk 2 Dynamic 4094 MB Online New Volume (G) 100 MB NTFS Healthy New Volume (G) 100 MB NTFS Healthy 3994 MB Unallocated 3994 MB Unallocated Volumes Free space combined into one logical volume Empty Empty Empty Data Data written to first disk until full, then to next disk in volume

24 Creating Striped Volumes Disk 1 Dynamic 4094 MB Online Disk 2 Dynamic 4094 MB Online New Volume (G) 100 MB NTFS Healthy New Volume (G) 100 MB NTFS Healthy 3994 MB Unallocated 3994 MB Unallocated Free space combined into one logical volume Data written across all disks in 64-KB units 64 KB 64 KB 64 KB

25 Volumes contd... Volumes do not protect your data, they only let you use the drive space efficiently If one hard disk used in a volume fails, the volume set is dead, even if the other hard disks are fine. Make sure to back up the volume set regularly, as more the no. of hard disks you have, the more likely it is that one will fail at any given time.

26 Mirror set Mirror sets are the simplest form of Win2K data redundancy Writing two copies of all data onto volumes on two separate disks so that if one disk fails, the data is still available. If anything happens to the disk storing original data, identical copy on the other half of the mirror set is still available. Collectively, the two volumes are called a mirror set. They have a couple of advantages: you can mirror an existing simple volume set, making it fault tolerant. Only two physical hard disks are required to implement mirror set.

27 Mirroring & Duplexing Disk Controller Disk Controller Disk Controller Disk Original Disk Mirrored Disk Original Disk Mirrored Disk Mirroring Disk Duplexing

28 Stripe set Volume sets are useful because they combine many differently sized areas of unused space into a single volume, but they don t offer performance benefits To use space on multiple disks and decrease read write time, use disk stripping without parity also called as RAID level 0 At least 2, but not more than 32 disks can be used

29 Stripe set Stripe set has an advantage over volume sets but A stripe set can not be extended. It s size remains fixed A stripe set can not be mirrored i.e., stripe set can not be made fault tolerant except for backing it up.

30 Disk Stripping without Parity Information Stripe Set Data A Data B Data C Data A Data B Data C Data A Data B Data C Member 1 Member 2 Member 3

31 RAID 5 Volume Also known as Stripe set with Parity This offers Data protection as well as efficiency Apart from the data (as in RAID level 0) the parity information is also written on the disk, always on a separate disk from the one where data it corresponds to is written. In case of failure of one disk in the array, data can be reconstructed from the parity information on the other disk. Every time the data is saved to the disk, the parity information must be updated to reflect its current status.

32 Disk Stripping with Parity Information Stripe Set Data A Data B Parity Info A Data C Parity InfoB Parity Info C Member 1 Member 2 Member 3

33 Hardware/Software RAID Hardware RAID is more expensive More efficient, as it can rebuild itself faster Allows you to hot-swap the bad drive

34 Disk Geometry & File Formats Physical Structure of a disk means tracks and sectors. Win2k imposes logical structure over this physical structure, called disk format and it groups sectors together in logical unit called cluster No. of sectors in a cluster varies, depending on the size of the disk partition and the disk format All clusters have at least one sector in any file system

35 Disk Geometry & File Formats A cluster is the smallest unit, that a file system can recognize, which means that only one file can be stored per cluster If the file is too big to fit in one cluster, then it will be spread over multiple clusters as close as possible If a file is smaller than the cluster size, it will still fit, but unused space in the cluster will go waste Larger clusters reduce the likelihood that files will get fragmented, but smaller clusters generally use the file space more efficiently

36 Disk formats File Systems NTFS FAT 16 FAT 32

37 FAT Standard file system used for DOS/Windows computers. It uses a File Allocation Table to note which cluster or clusters a file is stored in. If a file is stored in more than one cluster, then the cluster indicates a pointer to the next cluster for the file until the final cluster includes End of File marker. The Directory contains entries for file names and their attributes such as file size, attribute byte, modification time and date and starting allocation unit (which is a pointer to an entry in FAT)

38 Directory FAT Ex1.txt 0002 Ex2.txt 0001 Ex3.txt 0008 Ex1.txt chain links: 2,9 Ex2.txt chain links: 1,3,4,7 Ex3.txt chain links: 8,5, FFFF(end) FFFF(end) 0005 FFFF(end)

39 FAT 16 FAT 16 uses 16 bits addressing for the clusters, hence can address at most 2 16 clusters For large volumes, the cluster size will also become very big (32 KB) Maximum Volume size supported is 4 GB

40 FAT 32 FAT 32 uses 32 bits addressing for the clusters, hence can address at most 2 32 clusters, because of this, FAT 32 can use much smaller clusters (4 KB) On volume up to 8 GB, it uses 4 KB clusters Maximum Volume size supported is 32 GB and minimum is 512 MB

41 NTFS NTFS is the file system designed to be used with NT and WIn2k. File System Security Supports Encryption, Disk Quota,Volume Mounting, Data Compression Records log of disk activities, to restore the disk after a power failure In NTFS, files are treated as objects that have user and system defined attributes. These attributes are stored in the file itself. The system information, such as file name, file size, data etc. is part of the file.

42 Master File Table MFT Descriptor MFT Mirror Des. Log File Record Extents Small file record Big File Record Small dir record

43 File System Considerations Choose FAT partition, if you want it to be accessible from DOS, OS2 and NTFS You want to have multiple OS If you are installing on an existing partition, then keep the current files intact. Later on, the partition type can be changed. FAT system can be converted to NTFS, without having to backup the data, reformatting the disk and then starting over again You can not convert to any File system other then NTFS, and Reverse process is not possible

44 Defragmentation When the disk is new, file is created on adjacent clusters. As the disk is used (new files may be created, old files may be deleted) clusters may not be available in contiguous chain. When files in a disk are spread over several non-contiguous clusters, it is said to be defragmented.

45 Defragmentation With defragmentation the system performance degrades, it takes longer to access a file. It is harder to recover badly fragmented files then the ones that are stored in contiguous clusters. A highly fragmented system can cause Win2k to crash also.

46 Chkdsk Creates and displays a status report for a disk, based on the file system used. Chkdsk also lists and corrects errors on the disk. If chkdsk cannot lock the drive it will offer to check it the next time the computer restarts.

47 Encryption Encryption is the process of converting data into a format that cannot be read by another user. Once a user has encrypted a file, the file automatically remains encrypted whenever the file is stored on disk Decryption is the process of converting data from encrypted format back to its original format. Once a user has decrypted a file, the file remains decrypted whenever the file is stored on disk.

48 Quota Management The Quota Manager checks, the writes to the disk of protected volumes based on the criteria set by the network administrator. Users are not allowed to write on to the volumes that are at or exceed their preset quotas. It is based on user identity and the folder the user is storing information in.

49 Archiving Data - Remote Storage Service Remote Storage Service (RSS) lets you conserve room on relatively expensive hard disk media by automatically moving rarely used files to relatively cheap media when the disk space starts getting rare. During set up, files to be archived are marked When the space on the hard disk dips below the specified level RSS copies the file to the Remote Storage Media, leaving on the logical volume a place holder file linking it to the real file on the remote media.

50 Normal Backup A normal backup copies all selected files and marks each file as having been backed up (in other words, the archive attribute is cleared). With normal backups, you need only the most recent copy of the backup file or tape to restore all of the files. You usually perform a normal backup the first time you create a backup set.

51 Incremental Backup An incremental backup backs up only those files created or changed since the last normal or incremental backup. It marks files as having been backed up (in other words, the archive attribute is cleared). If you use a combination of normal and incremental backups, you will need to have the last normal backup set as well as all incremental backup sets in order to restore your data.

52 Differential Backup A differential backup copies files created or changed since the last normal or incremental backup. It does not mark files as having been backed up (in other words, the archive attribute is not cleared). If you are performing a combination of normal and differential backups, restoring files and folders requires that you have the last normal as well as the last differential backup.

53 Copy Backup A copy backup copies all selected files but does not mark each file as having been backed up (in other words, the archive attribute is not cleared). Copying is useful if you want to back up files between normal and incremental backups because copying does not affect these other backup operations.

54 Daily Backup A daily backup copies all selected files that have been modified the day the daily backup is performed. The backedup files are not marked as having been backed up (in other words, the archive attribute is not cleared).

55 Backup Backing up your data using a combination of normal backups and incremental backups requires the least amount of storage space and is the quickest backup method. However, recovering files can be time-consuming and difficult because the backup sets can be stored on several disks or tapes.

56 Backup Contd Backing up your data using a combination of normal backups and differential backups is more timeconsuming, especially if your data changes frequently, but it is easier to restore the data because the backup set is usually stored on only a few disks or tapes.

57 Review RAID Dynamic Disks FAT NTFS Backup