Monday, 23 December 2013

Fragmentation Notes

Fragmentation Notes

Fragmentation: (Unused Disk Space)
  • It will occur in a dynamic memory allocation when many of the free blocks are too small to satisfy any request.
External Fragmentation:  
  • Dynamic memory allocation algorithm allocate some memory and a small piece is left over (that cannot be effectively used).
Internal Fragmentation: 
  • Space wasted inside of the allocated memory blocks (allocated memory may be slightly larger than the requested memory)
Fragmentation occurring reasons:
  • When insert, update, delete operation perform
  • DB structure is not proper
  • When DB has dynamic calc & store members.
We cannot store more than 10 KB file into fragmentized space because no 10 KB free block is available on fragmentized disk. After defragmentation, we can do that.

Measuring Fragmentation: 
  • Using Average Fragmentation Quotient
  • Using Average Clustering Ratio
Steps for Defragmentation: 
      • EAS Console ⇒ Application ⇒ Right Click ⇒ Export ⇒ Level 0 Data Blocks
      • EAS Console ⇒ Application ⇒ Database ⇒ Right Click ⇒ Clear ⇒All Data
      • EAS Console ⇒ Application ⇒ Database⇒ Right Click ⇒ Load data ⇒ Find Data File
Another way for Reducing Fragmentation: 
      • EAS Console ⇒ Application ⇒ Database ⇒ Right Click ⇒ Restructure
Removing Security File Fragmentation: 
      • EAS Console ⇒ Essbase server ⇒ Security ⇒ Right Click ⇒ Compact Security File

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