HP XP P9500 Storage - Manual (Page 37)

system, the processing speed of Read and Write operations becomes slow. In this case, the
I/Os from the mainframe host may become MIH error.
•
If the host connected to the local storage system issues too many I/Os to be processed by the
external storage system, the commands from the host may possibly be timed out.
When the amount of I/Os from the host to the external volume exceeds the maximum amount
of I/Os that the external storage system can accept, the commands from the host to the local
storage system may possibly be timed out. As you configure the system using external volumes,
consider the capabilities of the external storage system.
•
When you execute commands of the P9500 program products to a mapped external volume
and thus too many I/Os are issued to be processed by the external storage system, the
commands may possibly be timed out and an error may occur.
When the amount of I/Os from the program products to the external volume exceeds the
maximum amount of I/Os that the external storage system can accept, the commands from
the program products may possibly be timed out and an error may occur. As you configure
the system using external volumes, consider the capabilities of the external storage system.
•
When you use an external volume from the host, note the Path Blockade Watch time for the
external volume. If the Path Blockade Watch time is longer than the timeout period of the host
command, the commands from the host may possibly be timed out when the power supply is
off or when an error occurs for the external storage system. If the host I/O is a significant
concern, make sure that the Path Blockade Watch time of the external volume is the same as
or shorter than the timeout period of the host command.
RAID level considerations
In the internal processing, the RAID level of the external volume is handled as RAID-1 across the
board. The bar (-) is displayed on the Remote Web Console windows. The RAID level of external
volumes is reported as RAID-1 when information about external storage system is reported to the
higher-level device (OS).
Thunder 9500V series guidelines
When you use the Thunder 9500V series storage system as an external storage system, the following
versions are recommended. If you use a 9500V storage system whose version is earlier than the
following versions, information about SATA drives may not be displayed correctly.
•
For Thunder 9530V, Thunder 9520V, Thunder 9570V: version 0658 or later
•
For Thunder 9580V, Thunder 9585V: version 1658 or later
AMS 2000 series guidelines
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When using an AMS 2000 series storage system as an external storage system, unnecessary
load to the external storage system should be avoided. When using this configuration, the
path mode between storage systems is Multi mode. Therefore, when many external paths and
mapping volumes are mapped, the load to the external storage system becomes high and
some commands from host to P9500 or from P9500 to the external storage system may time
out. To keep the proper load, the following is recommended.
◦ Define volumes of each AMS2000 series storage system to set external path number to
two. In this case, set the paths to the ports of each controller of AMS2000 series storage
system.
◦ Set the queue of commands that are issued at the same time from one AMS2000 series
storage system to 500 or less. The formula to calculate the number of the queue commands
per AMS2000 series storage system is as follows.
(number of queues) x (number of paths of external volumes) x (number of external volumes
that issue commands at the same time) < 500
Guidelines for External Storage operations 37