"# JNachos"

Implementation:

• Building on a fundamental operating system to expand its capabilities by implementing kernel mechanisms and high-level policies and incorporating a Log-Structure File System to reduce the seek time for small files.

• My Responsibilities:

o Kernel mechanisms such as

 fork

 exec

 exit

o Memory Virtualization

• A swap space was created which imported all pages of the current process.

• Least Recently Used algorithm was followed to evict a page from RAM when a page fault was encountered ensuring the availability of the required page in RAM.

o Log Structure File System:

• Implementing FileSystem interface with functions:

1.	Create

2.	Open

• Implementing OpenFile interface with functions:

1.	Read

2.	Write

• Models used to build the file system:

o InodeMap

o InodeMapValue

o BitMap (SectorMap, SegmentMap)

o InodeNormal

o LogOpenFile

o SegmentSummary

o SegmentSummaryValue

o LogStructureFileSystem

• Relationships

o	InodeMap has InodeMapValue

o	SegmentSummary has SegmentSummaryValue

o	LogStructureFileSystem has InodeMap, BitMap, SegmentSummary.

Model:

1. InodeMapValue:

   InUse: Boolean variable

   sectorNumberOfFile

   FileName

2. InodeMap:

   Array of InodeMapValue

   fetchFromTheFile(OpenFile)

   writeBackIntoTheFile(OpenFile)

   findTheFileWithName()

   addFileIntoDirectory()

3. BitMap:

   numClearNits

   array of Boolean values

   clear()

   writeback(OpenFile)

   fetchFrom(OpenFile)

   mark(int)

   getNextWhichIsFree()

   inverse()

4. InodeNormal:

   numBytes

   numSectors

   array of direct pointers (mDataSectors)

   filename

   allocate(SectorMap,fileSize,SegmentMap)

   fetchFrom(int sector)

   writeback(int sector)

5. SegmentSummaryValue:

   fileNames

6. Segment Summary:

   //last 8 sectors of each segment tracking which sector is used by which file.

   Array of SegmentSummaryValue

7. LogOpenFile : Implementation of OpenFile

   fileHeader

   mSeekPosition

   writeIntoDisk

   ReadFromDisk

8. LogStructureFileSystem

   findFreeSector()

   getCleanThreeSegments()

   cleanSegments(int[])

   writebackIntoSegmentFile()

   writebackIntoSectorFile()

   fillOutSegmentDS()

   fillOutSectorDS()

   Create()

   Open()