Anatomy of Filesystems..
Anatomy of HardisksTrack 1                                                   “Platter” – A circular piece of              ...
Anatomy of CommunicationCommunication in Humans:                                                Requirements:             ...
Communicating with your HardiskVarious communication standards exist to talk to our Harddisks: Communication Requirements ...
SCSI Overview  Target                                Host Bus Adapter(HBA)   ID: 0             8 Bit wide wires  Target   ...
SCSI Communication in Action          OS:      CPU: Give me Block 1, from disk0        OS: your        data, ”Hello”      ...
FileSystemsOrganize Scattered Data:                                                   Visible part of Metadata:For FileSys...
FileSystems - Dig DeeperFileSystem Blocks:FileSystem Block                                         Block 0 (4Kb, Block siz...
FileSystems – Contd…Block Groups:                                       Block Group 0         Super        Group Descripto...
FileSystems – Contd…Difference between file and directory Inode: File Inode :                                             ...
FileSystems – Contd…SuperBlock :                 Free Blocks                Free Inodes                     Size          ...
FileSystem in ActionListing Contents of a file:                                                             • Read the ino...
Thank You…   Email: bennojoy@gmail.com      bennojoy@gmail.com
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Anatomy of file_system

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Anatomy of file_system

  1. 1. Anatomy of Filesystems..
  2. 2. Anatomy of HardisksTrack 1 “Platter” – A circular piece of magnetic material “Tracks” – Platters divided into concentric circles Track 0 Read/Write Head 0 Platter1,track0Read/Write data from Hardisk ? Platter2,track0 Cylinder 0 Read Cylinder 0,head 0, Platter3,track0 sector 0. Disk Controller. CHS Addressing bennojoy@gmail.com Does operations like read, write etc..
  3. 3. Anatomy of CommunicationCommunication in Humans: Requirements: • Speaker/Listener • Voice/Language • Medium: Air • Addressing bennojoy@gmail.com
  4. 4. Communicating with your HardiskVarious communication standards exist to talk to our Harddisks: Communication Requirements SCSI Specification Speaker/Listener Initiator/Target Voice/Language SCSI Commands Medium SCSI Bus Addressing SCSI ID bennojoy@gmail.com
  5. 5. SCSI Overview Target Host Bus Adapter(HBA) ID: 0 8 Bit wide wires Target SCSI Bus Converts: PCI -Bus PCI -> SCSI CPU ID: 1 Initiator Target ID: 7Logical Block Addressing (LBA) – A Data Addressing Standardization: Block 0/1 Block 2/3 Track 0 Track 1 Sector 0 Sector 1 Sector 0 Sector 1SCSI Command bennojoy@gmail.com
  6. 6. SCSI Communication in Action OS: CPU: Give me Block 1, from disk0 OS: your data, ”Hello” CPU HBA: Give me Block 1, From Disk 0 CPU: Your data “Hello” Bus Adapter: Initiator Hey, Disk 0, I Need your attention Thanks, READ LBA 2 for me Ok Bus, You have my attention Converts LBA 2 –> CHS 0/0/1 Target Disk0Ok, Here is LBA 2 Data: “Hello” ID 0 bennojoy@gmail.com
  7. 7. FileSystemsOrganize Scattered Data: Visible part of Metadata:For FileSystems:• Index(TOC) = Metadata• Contents = Data bennojoy@gmail.com
  8. 8. FileSystems - Dig DeeperFileSystem Blocks:FileSystem Block Block 0 (4Kb, Block size)SCSI Block (LBA) Block 0 Block 1 Block … Block 8Disk Block Sector 0 Sector 1 Sector … Sector 8Fileystem layout on Disk: Boot Block Group 0 Block Group… Block Group .. N Block Block 0 Block 1 Block 2 Block 3 Block 4 Block N bennojoy@gmail.com
  9. 9. FileSystems – Contd…Block Groups: Block Group 0 Super Group Descriptor Inode Data Blocks … N Block Blocks.. BlocksInodes :Every file or Directory will have a corresponding Inode, which contains informationcorresponding to the file or directory Entries in an Inode : Inode Block: Owner Inode 1 Mode (permission/Directory/File) 128 bytes TimeStamp Inode 2 Address of 1st Data Block Inode … Address of 2nd Data Block Inode 32 Address of Direct and Indirect Data Block bennojoy@gmail.com
  10. 10. FileSystems – Contd…Difference between file and directory Inode: File Inode : Data Block 22: Owner Hello Mode (File) World ! TimeStamp Data Block 22 Address of 2nd Data Block Address of Direct and Indirect Data Block Directory Inode : Data Block 50: Owner Mode (Directory) “File1” - 32 TimeStamp “File2” - 36 Data Block 50 Address of 2nd Data Block Address of Direct and Indirect Data Block bennojoy@gmail.com
  11. 11. FileSystems – Contd…SuperBlock : Free Blocks Free Inodes Size Block Size etc..Group Descriptor : Block Number of First Inode No of free blocks in group Revisit the FileSystem Layout in Disk: bennojoy@gmail.com
  12. 12. FileSystem in ActionListing Contents of a file: • Read the inode entry of / (Root directory) • The root inode is fixed, inode entry 2 in the first inode block of the first blockgroup Test Inode Mode (Directory) “a” – Inode(5) Data Block 2 Root Inode Mode (Directory) A Inode “Test” – Inode(3) “hello world” Mode (File) “Bin” – Inode(4) Data Block 1 Data Block 3Inode1 Inode2 Inode3 Inode4 Inode5 Block1 Block2 Block3 Block4 Block5 bennojoy@gmail.com
  13. 13. Thank You… Email: bennojoy@gmail.com bennojoy@gmail.com

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