Mode Category Description Default MCU/RCU
Note: Set this SOM to ON when you want to enable the QoS
function.
701 Universal Volume
Manager
Issues the Read command at the logical unit discovery
operation using UVM.
Mode 701 = ON: The Read command is issued at the logical
unit discovery operation.
Mode 701 = OFF (default): The Read command is not
issued at the logical unit discovery operation.
Notes:
1. When the external storage is USP/NSC and the Open
LDEV Guard attribute (VMA) is defined on an external
device, set this SOM to ON.
2. As the VMA information is USP/NSC specific, this SOM
does not need to be ON when the external storage is
other thanUSP/NSC.
3. When this SOM is set to ON, it takes longer time to
complete the logical unit discovery. The amount of time
depends on external storages.
4. With this SOM OFF, if searching for external devices
with VMA ia set, the VMA information cannot be read.
5. When this SOM is set to ON while the following
conditions are met, the external volume is blocked:
• An external volume to which Nondisruptive
migration (NDM) attribute is set exists.
• The external volume is reserved by the host
6. Set this SOM to OFF when the following conditions are
met:
• An external volume to which Nondisruptive
migration (NDM) attribute is set exists.
OFF
-
704 ShadowImage
Volume Migration
To reduce the chance of MIH, this SOM can reduce the
priority of ShadowImage, Volume Migration, or Resync copy
internal IO requests so that host IO has a higher priority. This
SOM creates new work queues where these jobs can be
assigned with a lower priority.
Mode 704 = ON: Copy processing requested is registered
into a newly created queue so that the processing is
scheduled with lower priority than host I/O.
Mode 704 = OFF (default): Copy processing requested is
not registered into a newly created queue. Only the existing
queue is used.
Notes:
1. Apply this SOM when the load of host I/O to an ECC
that uses ShadowImage or Volume Migration is high
and the host I/O processing is delayed.
2. If the PDEV is highly loaded, the priority of Read/Write
processing made by ShadowImage, Volume Migration,
or Resync may become lower. As a consequence the
copy speed may be slower.
OFF -
721 Common When a parity group is uninstalled or installed, the following
operation is performed according to the setting of SOM 721.
OFF -
362 System option modes
System Administrator Guide for VSP Gx00 models and VSP Fx00 models
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