Here is a list of independent disk pool questions and answers. If you have a question that is not on this page, please contact us.
- How do independent disk pools work?
- How can independent disk pools be implemented in my environment?
- How should I structure my independent disk pools?
- What is a disk pool group?
- What is geographic mirroring?
iSeries™ Navigator graphical user interface
- How do I access the iSeries Navigator disk management function?
- What is the difference between the disk management functions in iSeries Navigator and the character-based command interface?
- How do I access the disk management function when the system is in dedicated service tools (DST) mode?
- What is the service tools server?
- Why does the data I see in iSeries Navigator appear to be out of date?
- Why can't I connect to the service tools server after I add the service table entry?
Configuring
- How do I create a new disk pool or independent disk pool?
- How do I create a disk pool group?
- How do I configure geographic mirroring?
Performance
Troubleshooting
- Why do no disk units appear as eligible to be added to my disk pool?
- Why doesn't the device description get deleted when I delete the disk pool?
- Why do I get a message saying the device description is already created?
- Why does the primary or secondary disk pool I try to create appear to be a UDFS disk pool?
- Why do I get a message that says my disk pool is not the right type when I try to create a library in it?
What is a CPDB716 message,
and how can it be fixed?
General
How do independent disk pools work?
The key characteristic of an independent disk pool is its ability to be, of course, independent of the rest of the storage on a server. It is independent because the data in the independent disk pool is self-contained. This means that all of the necessary system information associated with the data resides within the independent disk pool. See How independent disk pools work for details.
How can independent disk pools be implemented in my environment?
There are two basic environments in which you can take advantage of independent disk pools: a multi-system environment managed by an iSeries cluster, and a single-system environment with a single iSeries server. See Switchable and stand-alone independent disk pools for details.
How should I structure my independent disk pools?
IBM® provides some recommendations for structuring and populating your independent disk pools. See Recommended structure for independent disk pools for details.
A disk pool group is made up of a primary disk pool and zero or more secondary disk pools. Each disk pool is independent in regard to data storage, but in the disk pool group they combine to act as one entity. See Disk pool groups for details.
Geographic mirroring is a function that generates a mirror copy of an independent disk pool on a system that is (optionally) geographically distant from the originating site for availability or protection purposes. See Geographic mirroring for details.
iSeries Navigator graphical user interface
How do I access the iSeries Navigator disk management function?
Before you can access disk management functions in iSeries Navigator, you must complete some setup tasks. See Access disk management functions for details.
What is the difference between the disk management functions in iSeries Navigator and in the character-based (command) interface?
Support for many independent disk pool tasks are only available through iSeries Navigator. Almost all disk management functions that are available from the system service tools (SST) mode are available though iSeries Navigator. A number of disk management functions that are only available from the dedicated service tools (DST) mode are also available.
How do I access the disk management function when the system is in dedicated service tools (DST) mode?
Beginning with V5R1, the Disk Units folder in iSeries Navigator is available when the system is in dedicated service tools (DST) mode.
What is the service tools server?
The service tools server allows you to use your PC to perform service tools functions through TCP/IP. Before you attempt to use any disk management functions, you must configure the service tools server. See Set up communication for details.
Why does the data I see in the iSeries Navigator window appear to be out of date?
The disk management function in iSeries Navigator caches information, and therefore needs to be refreshed to have the most current data visible. After you make a configuration change, iSeries Navigator should refresh itself. If it does not, however, you can manually refresh it by clicking the Refresh button on the iSeries Navigator toolbar. You can also set iSeries Navigator to refresh periodically. Depending on the size of your server, however, you might not want to do this. Disk unit configuration data tends to be fairly static and does not need to be refreshed often. If your system is large, it can take a significant amount of time to download all information.
Why can't I connect to the service tools server after I add the service table entry?
The Add Service Table Entry (ADDSRVTBLE) command is case sensitive. In particular, it is important to ensure that the Protocol = 'tcp', and not 'TCP'. To ensure this is the case, use the Work with Service Table Entry (WRKSRVTBLE) command, and check the as-sts server field. Make sure that TCP is lowercase. If it is not, then remove the entry, and re-create it by issuing the following command exactly as shown:
ADDSRVTBLE SERVICE('as-sts') PORT(3000) PROTOCOL('tcp') TEXT('Service Tools Server') ALIAS('AS-STS')
Configuring
How do I create a new independent disk pool?
You can create an independent disk pool in a clustered, multisystem environment or on a single system. See the following topics for details:
How do I create a disk pool group?
See Create a new disk pool group for details.
How do I configure geographic mirroring?
You can configure geographic mirroring for independent disk pools that are dedicated or switchable between systems. See the following topics for details:
Performance
There are several factors that can influence performance. Make sure your PC's TCP/IP settings are configured correctly. Specifically, make sure that you do not have an incorrect secondary gateway. If you do have a secondary gateway, remove it. This should provide a significant increase in performance. See Requirements for geographic mirroring for more detailed information.
Why is performance slow for geographic mirroring?
For geographic mirroring you should consider the distance that the independent disk pool is being mirrored. The type and number of communication lines as well as their bandwidth have an effect on performance. You can configure up to four TCP/IP communication interfaces on multiple adapters. You should consider configuring multiple communication lines to allow for the highest performance. The volume of disk unit writes that your applications require also plays a role in the performance of your geographically mirrored independent disk pool.
Troubleshooting
Why do no disk units appear as eligible to be added to my disk pool?
There are a number of possible reasons for this. First, you must have an unconfigured disk unit to add. If the disk pool is protected, you can only add parity disks, or disks in pairs, so that they can be mirrored.
If your system is in a clustered environment, disk unit eligibility is more complex. Each disk unit is assigned a rank, which indicates its eligibility to be added to a particular disk pool. If the rank of the disk unit is above 300, then the disk is ineligible. A complete list of the ranks, and what they mean, is available in the disk management online help.
Why doesn't the device description get deleted when I delete the disk pool?
Because the device description does not always get created by the disk management function, it might not be deleted when the disk pool gets deleted. You need to manually delete it using the Delete Device Description (DLTDEVD) command.
Why do I get a message saying the device description is already created?
When you create a new independent disk pool, an attempt is made to create an associated device description. If a device description of the same name as the disk pool already exists, you will receive a warning message, and the existing device description will not be changed. Most of the time, this is not a problem. However, if the device description's name and associated resource do not match, this becomes a problem, and this is why you receive the warning message.
Why does the primary or secondary disk pool that I try to create appear to be a UDFS disk pool?
If iSeries Navigator failed or was closed while the disk pool was being created, you might need to Convert UDFS disk pools to a primary or secondary disk pool.
Why do I get a message that says my disk pool is not the right type when I try to create a library in it?
Make sure that the disk pool you are trying to create a library in is a primary or secondary disk pool, not a UDFS disk pool. If the disk pool is a UDFS disk pool and you want to create a library in it, you need to Convert UDFS disk pools to a primary or secondary disk pool.
What is a CPDB716 message, and how can it be fixed?
When a copy from an original ASP is made and there is an attempt to vary on the copy on the system that had used the original ASP, message CPDB716 appears. Before the system accepts the copy, an IPL must be performed.