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.

Note:
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