System option modes for ShadowImage for Mainframe

To provide greater flexibility, the storage systems have additional operational parameters called system option modes (SOMs) that allow you to tailor the storage system to your unique operating requirements. The SOMs are set by your service representative. Work with your service representative to ensure that the appropriate SOMs for your operational environment are configured on your storage system.

Note:

The SOM information might have changed since this document was published. For the latest SOM information, contact customer support.

SOM	Title	Description
467	Copy Threshold Option	When the storage system is under heavy load, it temporarily stops the copy processing to minimize the degradation of I/O performance of the host server. The copy threshold option is enabled only when the workload is heavy. If you set the copy threshold option, the feature is enabled for the following software: ShadowImage ShadowImage for Mainframe Compatible FlashCopy^® V2 Volume Migration
789	Copy threshold option that operates during I/O from the host server to the primary volume	When the storage system is under heavy load, it temporarily suspends the copy operation that operates during I/O from the host server to the primary volume. This option minimizes the degradation of I/O performance to each volume of CLPR to which the secondary volume belongs. ON (default) (recommended value): Suppresses the copy operation that occurs during I/O from the host server to the primary volume when the cache write pending rate of the MP unit of the CLPR to which the secondary volume belongs is 70% or more. OFF: Suppresses the copy operation that occurs during I/O to the primary volume when the cache write pending rate of the MP unit of the CLPR to which the secondary volume belongs is as follows. However, if the cache write pending rate is high, I/O performance to each volume in CLPR to which the secondary volume belongs might be degraded. Threshold for the cache write pending rate at which copy operations are suppressed: (VSP One B20 series) Volumes whose emulation type is 3380-A or 3390-A: Some of local replica options from "Host I/O Priority Mode 1" to "Host I/O Priority Mode 5" are enabled: 70% or more Local replica options from "Host I/O Priority Mode 1" to "Host I/O Priority Mode 5" are all disabled: 75% or more (VSP One Block 85) DRS-VOLs (P-VOL or S-VOL): Some of local replica options from "Host I/O Priority Mode 1" to "Host I/O Priority Mode 5" are enabled: 70% or more Local replica options from "Host I/O Priority Mode 1" to "Host I/O Priority Mode 5" are all disabled: 75% or more Other volumes: 90% or more
790	Copy threshold option that operates during I/O from the host server to the secondary volume	When the storage system is under heavy load, it temporarily suspends the copy processing that occurs during I/O from the host server to the secondary volume. The storage system minimizes the degradation of I/O performance to each volume of CLPR to which the secondary volume belongs. ON (default) (recommended value): When the cache write pending rate of the MP unit of the CLPR to which the secondary volume belongs is 60% or more, the copy operation that occurs during I/O from the host server to the secondary volume is suppressed. OFF: When the cache write pending rate of the MP unit of the CLPR to which the secondary volume belongs is as follows, the copy operation that occurs during I/O to the secondary volume is suppressed. However, if the cache write pending rate is high, I/O performance to each volume in CLPR to which the secondary volume belongs might be degraded. Threshold for the cache write pending rate at which copy operations are suppressed: (VSP One B20 series) Volumes whose emulation type is 3380-A or 3390-A: 75% or more (VSP One Block 85) DRS-VOLs (P-VOL or S-VOL): 75% or more Other volumes: 90% or more
1254	Copy threshold option for capacity saving (per storage system)	Copy threshold option for capacity saving that is used when you want to prevent a decrease in the I/O performance (response) on DRS-VOLs from the host server. Use this option when you want to apply the functionality uniformly to all CLPRs in the storage system. If you want to apply different functions to each CLPR destination, use SOM 1260. This option allows you to choose whether or not to suppress the copy operation that is performed in the background when the MP unit of the CLPR of the destination volume has a cache write pending rate of 35% or more. ON: When the cache write pending rate of the MP units of the CLPR of the destination volume is 35% or more, the copy operation that runs in the background is suppressed, and the increase in the cache write pending rate of the destination storage system is suppressed. OFF: Follows the settings in the Copy Threshold option (SOM 467). Note: For details including the application flow of copy threshold options, see the section on copy threshold options in the Provisioning Guide.
1260	Copy threshold option for capacity saving (per CLPR)	Copy threshold option for capacity saving that is used when you want to prevent a decrease in the I/O performance (response) on DRS-VOLs of the host server. Use this option when you want to apply different features to each destination CLPR. If you want to apply a uniform feature to all CLPRs in the storage system, use SOM 1254. This option allows you to choose whether or not to suppress the copy operation that runs in the background when the MP unit of the CLPR of the destination volume has a cache write pending rate of 35% or more. ON: When the cache write pending rate of the MP units of the CLPR of the destination volume is 35% or more, the copy operation that runs in the background is suppressed, and the increase in the cache write pending rate of the destination storage system is suppressed. OFF: Follows the settings in the Copy Threshold option (SOM 467). Note: For details including the application flow of copy threshold options, see the section on copy threshold options in the Provisioning Guide.