Best Practice for IBMi with Data Domain VTL System
Summary: Some Best Practices to consider when setting up a VTL for an IBMi System
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Symptoms
.
Follow IBM i best practices to ensure the most successful VTL implementation and minimize troubleshooting issues after
configuration. This KB describes some best practices to implement virtual tape devices in the IBM i environment.
Follow IBM i best practices to ensure the most successful VTL implementation and minimize troubleshooting issues after
configuration. This KB describes some best practices to implement virtual tape devices in the IBM i environment.
Cause
.
Resolution
Configuration
Proper environment maintenance is critical to the operation of tape devices on the IBM i system. Use system service tools
(SST) to clear failed and non-reporting tape devices from the VTL configuration to ensure that "phantom" devices do not
conflict with new operational devices. If a failed device cannot be removed from the configuration, use concurrent
maintenance to power off the card and clear the failed device from the configuration. Reserved physical resource names can
also be cleared from the work with resource by resource name in SST.
Tape devices on HBAs that are dynamically allocated between logical partitions (LPARs) are an exception. These non-
reporting devices serve as placeholders for devices that may reappear at a later time.
Do not:
Include more than one initiator/target pair in a zone for tape devices.
Use multipathing on IBM i tape devices.
Change the zoning of an existing tape library or device after configuration.
Note: Zoning changes generates a new library and device, and requires remapping logical resources to the new physical
resource. If autoconfigure is active, new logical devices are created. Since all tape management scripts use the logical
name of the library or device to access the virtual device, any dependant operations will fail.
For legacy HBAs with a separate IOP, verify the IOP is dedicated to the tape IOA. While a shared IOP is supported for
tape, it represents a bottleneck, especially if shared with a disk controller. A shared IOP also prevents the IPL of the IOP
to automatically configure new tape libraries or devices. Use autoconfigure wherever possible to ensure all parameters of
the tape device are configured in a supported mode.
To assign the tape libraries and devices to IBM i LPARs, build a design that considers all of the environment
requirements. In an environment with high throughput requirements, balance the load across the host and VTL HBAs. In an
environment with multiple hosts, balance the overall workload during save operations across available VTL connections.
For the new generation of Smart IOAs, load the required PTFs and review the informational APAR about the requirements
for these new HBAs.
The latest Cumulative, HIPER and Database PTF packages should be applied, in addition to the BRS group PTF package.
Check following IBMi support page for the latest available Group PTF for your specific IBMi Version:
https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/IBM%20Removable%20Media%20on%20IBM%20i/page/Group%20PTFs
For more information on required and supported PTF levels see the also the the online Backup Compatibility Guide :
http://compatibilityguide.emc.com:8080/CompGuideApp/getDataDomainHardwareReportPage.do?hardwareReport=IBM%20i%20PTF
Optimize tape libraries assigned to an FC port for throughput. Additional drives assigned to an FC port will not necessarily reduce save times. Testing on Smart IOAs shows that four concurrent backup streams on a single host port will likely maximize the efficiency of backup times. Additionally, Smart IOAs are slower to check in devices than the IOP cards, and a large number of devices may result in certain devices displaying as non-operational on IPL, leading to failed logical resources. In this case, set the logical resource to not vary on an IPL, and use a startup routine to vary the library. This is described in the IBM APAR II13772, available on the IBM website.
Proper environment maintenance is critical to the operation of tape devices on the IBM i system. Use system service tools
(SST) to clear failed and non-reporting tape devices from the VTL configuration to ensure that "phantom" devices do not
conflict with new operational devices. If a failed device cannot be removed from the configuration, use concurrent
maintenance to power off the card and clear the failed device from the configuration. Reserved physical resource names can
also be cleared from the work with resource by resource name in SST.
Tape devices on HBAs that are dynamically allocated between logical partitions (LPARs) are an exception. These non-
reporting devices serve as placeholders for devices that may reappear at a later time.
Do not:
Include more than one initiator/target pair in a zone for tape devices.
Use multipathing on IBM i tape devices.
Change the zoning of an existing tape library or device after configuration.
Note: Zoning changes generates a new library and device, and requires remapping logical resources to the new physical
resource. If autoconfigure is active, new logical devices are created. Since all tape management scripts use the logical
name of the library or device to access the virtual device, any dependant operations will fail.
For legacy HBAs with a separate IOP, verify the IOP is dedicated to the tape IOA. While a shared IOP is supported for
tape, it represents a bottleneck, especially if shared with a disk controller. A shared IOP also prevents the IPL of the IOP
to automatically configure new tape libraries or devices. Use autoconfigure wherever possible to ensure all parameters of
the tape device are configured in a supported mode.
To assign the tape libraries and devices to IBM i LPARs, build a design that considers all of the environment
requirements. In an environment with high throughput requirements, balance the load across the host and VTL HBAs. In an
environment with multiple hosts, balance the overall workload during save operations across available VTL connections.
For the new generation of Smart IOAs, load the required PTFs and review the informational APAR about the requirements
for these new HBAs.
The latest Cumulative, HIPER and Database PTF packages should be applied, in addition to the BRS group PTF package.
Check following IBMi support page for the latest available Group PTF for your specific IBMi Version:
https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/IBM%20Removable%20Media%20on%20IBM%20i/page/Group%20PTFs
For more information on required and supported PTF levels see the also the the online Backup Compatibility Guide :
http://compatibilityguide.emc.com:8080/CompGuideApp/getDataDomainHardwareReportPage.do?hardwareReport=IBM%20i%20PTF
Optimize tape libraries assigned to an FC port for throughput. Additional drives assigned to an FC port will not necessarily reduce save times. Testing on Smart IOAs shows that four concurrent backup streams on a single host port will likely maximize the efficiency of backup times. Additionally, Smart IOAs are slower to check in devices than the IOP cards, and a large number of devices may result in certain devices displaying as non-operational on IPL, leading to failed logical resources. In this case, set the logical resource to not vary on an IPL, and use a startup routine to vary the library. This is described in the IBM APAR II13772, available on the IBM website.
Additional Information
.
Affected Products
Data Domain Virtual Tape Library for IBM I/OSProducts
Data Domain, Data Domain Virtual Tape Library for IBM I/OSArticle Properties
Article Number: 000065557
Article Type: Solution
Last Modified: 20 Nov 2020
Version: 2
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