Interface
When executing initial copy only
When executing Initial and
Update copy at the same time
When initial
copy pace
specified at the
time of pair
creation is 1 to
4
When initial
copy pace
specified at the
time of pair
creation is 5 to
15
When initial
copy pace
specified at the
time of pair
creation is 1 or
2
When initial
copy pace
specified at the
time of pair
creation is 3 to
15
Device
Manager -
Storage
Navigator
User-specified
value
4 User-specified
value
2
CCI User-specified
value
4 User-specified
value
2
The following table shows example settings.
Round trip
time
between
primary and
secondary
systems [ms]
Data path
speed
between
primary
and
secondary
systems
(MB/ms)
Number of
data paths
between
primary and
secondary
systems
Copy Pace
Number of
maximum
initial copy
VOLs
Round
trip
time
specifie
d [ms]
0 0.1 4 4 64 160
30 0.1 4 4 64 220
100 0.1 4 4 64 360
Determining Minimum Number of Remote Paths
You specify the minimum number of remote paths to the secondary system
when you set up the TC association between primary and secondary systems.
Using the Minimum Number of Paths option, you set a minimum value
from one to eight paths, with one being the default.
If the number of paths in Normal status drops below the specified minimum,
the primary storage system splits the pair to avoid impact to host
performance.
• To maintain high performance in the primary storage system, Hitachi
recommends setting the minimum number at two.
• For a pair with important data, set the minimum at one. This allows the
system to continue update operations to the secondary system.
• You can protect data integrity between P-VOL and S-VOL in the event that
the system splits the pair because the number of paths is lower than the
minimum. With the Fence Level setting (specified during the initial copy),
you decide whether, when the pair is split due to an error, the host
Planning for TrueCopy
3-7
Hitachi TrueCopy® User Guide for Hitachi Virtual Storage Platform Gx00 and Fx00 Models
To Next Page
Loading...
