HP XP7 Storage - Manual (Page 24)

1. Using your performance monitoring software, collect the following:
•
Disk-write bytes-per-second (MB/s) for every physical volume that will be replicated.
•
Data should be collected over a 3 or 4-week period to cover a normal, full business cycle.
•
Data should be collected at 5 minute intervals. If you use averages, shorter intervals
provide more accuracy.
2. At the end of the collection period, convert the data to MB/second, if needed, and import
into a spreadsheet tool.
Data transfer speed considerations
This topic discusses the speed that data must be transferred in order to maintain the Cnt Ac-J Z
system your are designing.
The ability of your Cnt Ac-J Z system to transfer data in a timely manner depends directly on the
following two factors:
•
RAID group configuration
•
Fibre-channel port configuration
Both of these elements must be planned to be able to handle the amount of data and number of
transactions your system will move under extreme conditions.
RAID group configuration
A RAID group can consist of physical volumes with a different number of revolutions, physical
volumes of different capacities, and physical volumes of different RAID configurations (for example,
RAID-1 and RAID-5). The data transfer speed of RAID groups is affected by physical volumes and
RAID configurations.
•
The data transfer speed of a journal volume depends on the data transfer speed of the RAID
group to which it belongs. A RAID group can consist of one or more volumes, including journal
volumes.
•
Each RAID group has a different throughput rating. The number of MB/sec that volumes in a
RAID group are capable of processing is published in Cnt Ac-J Z specifications.
•
Journal volumes must be configured in RAID groups according to the group’s throughput
specification and your system’s peak write-workload. If write-workload exceeds the RAID
group’s throughput rating, then the number of RAID groups must be increased.
•
Frequent read/write activity to non-journal volumes in a RAID group results in fewer read/writes
by journal volumes in the same RAID group. This can cause a drop in the data transfer speed
of journal volumes. To avoid this effect, place journal volumes and frequently accessed
non-journal volumes in different RAID groups.
Fibre-channel port configuration
The fibre-channel ports on your XP7 system have an IOPS threshold. Use the performance monitoring
information for the number of IOPS your production system generates to calculate the number of
fibre-channel ports the Cnt Ac-J Z system requires.
Please see “Planning ports for data transfer ” (page 45) for a full discussion on the type and number
of fibre-channel ports required for your system.
Sizing journal volumes
Journals volumes should be sized to meet all possible data scenarios, based on your business
requirements. If the amount of data exceeds capacity, performance problems and suspensions
result.
24 Planning volumes, XP7 systems