The minicopy operation
can be used at the discretion of the system manager and at a time
chosen by the system manager.
Because minicopy can significantly reduce the time it takes
to return a member to a shadow set, it gives system managers greater
flexibility in scheduling the removal and return of a shadow set
member, and it improves availability.
The time needed to perform a minicopy is proportional to the
amount of change that occurred to a shadow set in the disk's absence.
A shorter copy time gives sites more flexibility in managing backups.
Table 1 Comparison of Minicopy and Full Copy Performance
Percentage of Bits
Set
Time
for Full Copy (seconds)
Time for Minicopy (seconds)
Minicopy Time as Percentage
of Full Copy Time
100%
4196.09
3540.21
84.4%
90%
3881.95
3175.92
81.8%
80%
3480.50
2830.47
81.3%
75%
3290.67
2614.87
79.5%
70%
3194.05
2414.03
75.6%
60%
2809.06
2196.60
78.2%
50%
2448.39
1759.67
71.9%
40%
2076.52
1443.44
69.5%
30%
1691.51
1039.90
61.5%
25%
1545.94
775.35
50.2%
20%
1401.21
682.67
48.7%
15%
1198.80
554.06
46.2%
10%
1044.33
345.78
33.1%
5%
905.88
196.32
21.7%
2%
712.77
82.79
11.6%
1%
695.83
44.90
6.5%
Comparison of Minicopy and Hardware-Assist (DCD) Copy Performance shows
the results from another series of tests, comparing performance
times of a hardware assisted copy (using MSCP disk copy data (DCD)
commands on an HSJ controller) with a minicopy over a spectrum of write
activity.
Table 2 Comparison of Minicopy and Hardware-Assist (DCD) Copy Performance