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Anatomy of file_system

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Benno Joy

The document discusses the anatomy of file systems and how they are organized on hard disks. It explains that file systems organize scattered data using indexes containing metadata and data blocks containing file contents. File system blocks are mapped to disk blocks using logical block addressing. File systems use inodes to store file and directory metadata, with each file or directory having a corresponding inode containing attributes like owner, size, and pointers to data blocks. Block groups contain groups of inodes and data blocks to organize the file system layout on disk.

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Anatomy of Filesystems..
Anatomy of Hardisks Track 1 ¡°Platter¡± ¨C A circular piece of magnetic material ¡°Tracks¡± ¨C Platters divided into concentric circles Track 0 Read/Write Head 0 Platter1,track0 Read/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..
Anatomy of Communication Communication in Humans: Requirements: ? Speaker/Listener ? Voice/Language ? Medium: Air ? Addressing bennojoy@gmail.com
Communicating with your Hardisk Various 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
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: 7 Logical Block Addressing (LBA) ¨C A Data Addressing Standardization: Block 0/1 Block 2/3 Track 0 Track 1 Sector 0 Sector 1 Sector 0 Sector 1 SCSI Command bennojoy@gmail.com
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 ¨C> CHS 0/0/1 Target Disk0 Ok, Here is LBA 2 Data: ¡°Hello¡± ID 0 bennojoy@gmail.com
FileSystems Organize Scattered Data: Visible part of Metadata: For FileSystems: ? Index(TOC) = Metadata ? Contents = Data bennojoy@gmail.com
FileSystems - Dig Deeper FileSystem Blocks: FileSystem Block Block 0 (4Kb, Block size) SCSI Block (LBA) Block 0 Block 1 Block ¡­ Block 8 Disk Block Sector 0 Sector 1 Sector ¡­ Sector 8 Fileystem 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
FileSystems ¨C Contd¡­ Block Groups: Block Group 0 Super Group Descriptor Inode Data Blocks ¡­ N Block Blocks.. Blocks Inodes : Every file or Directory will have a corresponding Inode, which contains information corresponding 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
FileSystems ¨C 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
FileSystems ¨C 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
FileSystem in Action Listing 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¡± ¨C Inode(5) Data Block 2 Root Inode Mode (Directory) A Inode ¡°Test¡± ¨C Inode(3) ¡°hello world¡± Mode (File) ¡°Bin¡± ¨C Inode(4) Data Block 1 Data Block 3 Inode1 Inode2 Inode3 Inode4 Inode5 Block1 Block2 Block3 Block4 Block5 bennojoy@gmail.com
Thank You¡­ Email: bennojoy@gmail.com bennojoy@gmail.com

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Anatomy of file_system

  • 2. Anatomy of Hardisks Track 1 ¡°Platter¡± ¨C A circular piece of magnetic material ¡°Tracks¡± ¨C Platters divided into concentric circles Track 0 Read/Write Head 0 Platter1,track0 Read/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. Anatomy of Communication Communication in Humans: Requirements: ? Speaker/Listener ? Voice/Language ? Medium: Air ? Addressing bennojoy@gmail.com
  • 4. Communicating with your Hardisk Various 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. 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: 7 Logical Block Addressing (LBA) ¨C A Data Addressing Standardization: Block 0/1 Block 2/3 Track 0 Track 1 Sector 0 Sector 1 Sector 0 Sector 1 SCSI Command bennojoy@gmail.com
  • 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 ¨C> CHS 0/0/1 Target Disk0 Ok, Here is LBA 2 Data: ¡°Hello¡± ID 0 bennojoy@gmail.com
  • 7. FileSystems Organize Scattered Data: Visible part of Metadata: For FileSystems: ? Index(TOC) = Metadata ? Contents = Data bennojoy@gmail.com
  • 8. FileSystems - Dig Deeper FileSystem Blocks: FileSystem Block Block 0 (4Kb, Block size) SCSI Block (LBA) Block 0 Block 1 Block ¡­ Block 8 Disk Block Sector 0 Sector 1 Sector ¡­ Sector 8 Fileystem 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. FileSystems ¨C Contd¡­ Block Groups: Block Group 0 Super Group Descriptor Inode Data Blocks ¡­ N Block Blocks.. Blocks Inodes : Every file or Directory will have a corresponding Inode, which contains information corresponding 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. FileSystems ¨C 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. FileSystems ¨C 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. FileSystem in Action Listing 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¡± ¨C Inode(5) Data Block 2 Root Inode Mode (Directory) A Inode ¡°Test¡± ¨C Inode(3) ¡°hello world¡± Mode (File) ¡°Bin¡± ¨C Inode(4) Data Block 1 Data Block 3 Inode1 Inode2 Inode3 Inode4 Inode5 Block1 Block2 Block3 Block4 Block5 bennojoy@gmail.com
  • 13. Thank You¡­ Email: bennojoy@gmail.com bennojoy@gmail.com