HP XP Business Copy Software - Manual (Page 42)

Cautions on switching off the power supply
To switch off the power supply of the disk array during BC operations, make sure to:
• Complete copying for the BC pair in COPY(SP) or PSUS(SP) status first to change the pair status
from COPY(SP) or PSUS(SP) to PSUS, and then switch off the power supply. If shared memory is
volatilized when you switch on the power supply again, the pair in COPY(SP) or PSUS(SP) status
changes to PSUE.
NOTE:
If the shared memory is volatilized when you switch on the power supply again, the pair in the
COPY(SP) or PSUS(SP) status changes to PSUE.
NOTE:
If the status of only a part of the pairs in the same consistency group is changed, the processing
of At-Time Split function may not resume when you switch on the power supply, and the status of
some pairs may remain unchanged.
• Establish a timetable for BC copying operations. If shared memory is volatilized when you switch
on the power supply again, the following conditions occur:
• If the BC pair was in COPY(PD) or COPY(SP) status, data already copied becomes target data
to be copied after the power supply is switched back on. Even if there is no host I/O, the data
consistency rate does not reach 100% when the BC pair status changes to PAIR. When the
BC pair status changes to PAIR, target data is copied to the secondary volume.
• If the BC pair was in PAIR status, data already copied becomes target data to be copied after
the power supply is switched back on. In this case, the data consistency rate is 0%, and target
data is copied to the S-VOL.
• If the BC pair was in PSUS status, the entire volume becomes differential data. In this case, the
data consistency rate is 0%, and the entire volume is copied to the secondary volume when
you perform the pairresync operation.
Cautions on using the XP10000
The XP10000 has a fewer processors than the XP12000. Therefore, BC copy processing sometimes
takes a long time and host I/O performance may degrade. Consider the following:
• Copy processing
When you use BC on the XP10000, copy processing time (such as pair creation, pair split, and
pair resynchronization) might take longer compared to when you use BC on the XP12000. Copy
processing time changes according to the number of pairs, and sometimes the XP10000 requires
two to eight times the copy processing time compared to the XP12000.
• Host I/O performance
Since BC copy processing uses processors, host I/O performance might degrade during copy
processing. The number of processors in the XP10000 is small, therefore, when you use the
XP10000, the impact of copy processing on host I/O performance is larger than when you use
the XP12000. To mitigate host I/O performance degradation, reduce the copy pace or use the
Host I/O Performance option.
Business Copy XP (BC) for the Array 42