For all files in a mount path, Commvault uses the following formula to determine the fragmentation percentage:
(Total number of excess fragmentation/Total number of allowed fragmentation) * 100
The Per File Fragmentation Threshold configuration parameter available in Media Management Configuration (Service Configuration) tab sets the number of allowed fragments per file. The default value is 10. This means that within the 2GB chunks of a mount path, if the number of fragments is greater than 10 (for example, n, where n>10), then the file is considered to be a fragment and the excess fragment (n-10) is counted.
The following is an example of a mount path with five chunks (assuming a block size of 4096K as block content, below a value of 4096 will have no fragments).
Per-file fragmentation threshold = 10
|
Name (files |
Size |
Number of Fragments |
Number of Excess Fragments |
|---|---|---|---|
|
MEDIA_LABEL |
64 K |
0 |
0 |
|
CHUNK_1 |
2 GB |
53 |
43 |
|
CHUNK_2 |
2 GB |
9 |
0 |
|
CHUNK_3 |
2 GB |
14 |
4 |
|
CHUNK_4 |
2 GB |
26 |
16 |
|
CHUNK_5 |
2 GB |
5 |
0 |
|
CMT_1 |
64 KB |
0 |
0 |
|
CMT_2 |
64 KB |
0 |
0 |
|
CMT_3 |
64 KB |
0 |
0 |
|
CMT_4 |
64 KB |
0 |
0 |
|
CMT_5 |
64 KB |
0 |
0 |
The mount path in the table shows excess fragmentation = 63 (43 + 4 + 16)
Total number of files = 11
Allowed fragmentation = (total number of files * per-file fragmentation threshold) = 11 * 10 = 110
Total fragmentation percentage = (Total excess fragmentation / Total allowed fragmentation) * 100
= (63 /110) * 100 = 58%
Note
You can increase or decrease per-file fragmentation threshold to control the fragmentation percentage watermark.