HP Integrity NonStop H-Series - Manual (Page 87)

WVP NonStop Storage Analyzer User Guide – 536988-001
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4-9 Fragmentation
This section explains the data collection about free fragments available in Physical Disks on the
current node.
4-9-1 Overview
NonStop Storage analyzer reports the fragmentation information by finding out the various free
extent sizes and the number of free extents on a disk. The size of each extent is reported as a page
consisting of 2048 bytes (2 KB). For example, let’s assume the following Free Extents information
about a Disk:
Free Extent
Size (Pages) Free Extents
Count Total Page Size
(Extents size X Extent
Count)
Size (MB)
(Page Size X .002048)
2 5 10 0.004096
4 2 8 0.008192
6 1 6 0.012288
8 3 24 0.016384
32 1 32 0.065536
1168 1 1168 2.392064
1728 1 1728 3.538944
13984 1 13984 28.639232
36864 1 36864 75.497472
785296 1 785296 1608.286208
47830139 1 47830139 97956.12467
So from this information, Storage Analyzer calculates the total number of Free Extents (also known
as Fragmentation Free value) and depending on the total size (MB) of the fragments they are
distributed into five categories: <=1 MB, <=10 MB, <=100 MB, <=1 GB and >1 GB. So from the
above data we can infer the following:
Fragment Count Total Size (MB)
<= 1 MB 12
(5+2+1+3+1) 0.2
(5 * 0.004096 + 2 * 0.008192 + 0.012288
+ 3 * 0.016384 + 0.065536 )
<= 10 MB 2 5.9
(2.392064 + 3.538944)
<= 100 MB 2 104.1
(28.639232 + 75.497472)