Dynamically modifying the resources of an active partition

You can use the Partition Details task to add processors, memory, and devices to an active partition, without stopping and restarting it. When you click Apply to save any changes you have made through the Partition Details task, DPM updates the partition definition but does not bring any of the new resources or devices online. To do so, you must use the appropriate operating system or hypervisor commands. Note that you cannot change the partition type through the Partition Details task.

Depending on the version of Linux® that you have installed, the operating system might automatically configure some partition resources:
  • Remote Direct Memory Access (RDMA) over Converged Ethernet (RoCE) devices are automatically configured when you are running any of the minimum supported Linux versions. For recommended Linux on IBM Z® and LinuxONE distribution levels, see the IBM® tested platforms at: https://www.ibm.com/support/pages/linux-ibm-z-tested-platforms
  • Auto-configuration of other devices requires a version of the Linux operating system that supports auto-configuration. These other devices include Fibre Channel connections (FICON®) in Fibre Channel Protocol (FCP) mode, IBM HiperSockets, and Open Systems Adapter-Express (OSA-Express) devices. See the Red Hat®, SUSE, or Ubuntu product information page to determine which RHEL, SLES, or Ubuntu Server version provides this support.

To manually configure partition resources on the HMC and on the operating system that a partition hosts, use the following examples as models for your changes. Note that the content of the screen captures in these topics might differ from what you see on the HMC, depending on the DPM version and the host system that you are using.

Example: Adding more processor resources

Consider the display in the following screen, which shows that a sample partition has two threads per core, with eight processors online.
Figure 1. Sample display for the lscpu command showing current processor resources
This screen shows the Linux lscpu command and a sample of the resulting display.

To bring more processors online, complete the following steps.

  1. Use the Partition Details task to increase the number of processors for this partition from four to six cores, and click Apply to save your changes and close the Partition Details window.
    Figure 2. Sample screen of the Processors section in the Partition Details window
    This screen shows the Processors section of the Partition Details task.
  2. Through the Linux lscpu command, verify that the number of processor cores has increased.
    Figure 3. Sample display for the lscpu command showing additional processor resources
    This screen shows the Linux lscpu command and a sample of the resulting display.
  3. Use the Linux chcpu command to configure and then enable the additional processor cores.
    Figure 4. Sample display for the lscpu command showing configured processor resources
    This screen shows the Linux chcpu command used with configuration and enablement attributes, along with samples of the resulting displays.

Example: Adding more memory resources

Consider the display in the following screen, which shows that a sample partition has 1 terabyte (TB) of memory online, and 2 TB offline. It also shows that the memory size is in 8 gigabyte (GB) increments.
Figure 5. Sample display for the lsmem command
This screen shows the Linux lsmem command and a sample of the resulting display.

To bring more memory online, complete the following steps.

  1. Use the Partition Details task to increase the amount of memory for this partition from 1 TB to 2 TB, and click Apply to save your changes and close the Partition Details window.
    Figure 6. Sample screen of the Memory section in the Partition Details window
    This screen shows the Memory section of the Partition Details task.
  2. Then, through the Linux chmem command, increase the amount of online memory in 8 GB increments.
    Figure 7. Sample display for the chmem command
    This screen shows the Linux chmem command and a sample of the resulting display.

Example: Adding a new network device

In this example, the Linux operating system currently has seven network devices configured, as shown in the following display.
Figure 8. Sample display for the lscss command showing current devices
This screen shows the Linux lscss command with a resulting display of seven network devices.
  1. Use the Partition Details task to add a new network interface card (NIC).
    Figure 9. Sample screen of the Network section with the New NIC icon highlighted
    This screen shows the Network section of the Partition Details task.
  2. Select the adapter for the new network connection.
    Figure 10. Sample screen of the New Network Interface Card window
    This screen shows the New Network Interface Card dialog.
  3. Click OK to save the new NIC definition, and check the updated NICs table in the Network section of the Partition Details task.
    Figure 11. Sample screen of the Network section with the newly added NIC
    This screen shows the updated NICs table in the Network section.
  4. Click Apply to save your changes and close the Partition Details window.
  5. Then, through the Linux znetconf command, define the new devices 0.0.0008 through 0.0.000a.
    Figure 12. Sample display for the znetconf command showing current devices
    This screen shows several Linux znetconf commands with their resulting displays.
    Notes: If the display for the znetconf -u command does not list the newly added device:
    • The adapter might be offline. Use the lschp command to determine the current state of the new adapter, and use the chchp command to bring the adapter online. Then issue the znetconf command again.
    • The device might be included in a list of devices to be ignored by Linux. If cio_ignore is active, the list is automatically adjusted to accommodate all devices that are configured on the HMC interface only when you reboot the operating system. To dynamically add the device, use cio_ignore -r to remove the device from the list, then set the device online.

Issuing an lsqeth command displays the successfully defined network device, which can be defined to the Linux TCP/IP stack or passed to a virtual switch. Figure 13 illustrates a sample display for the lsqeth command.

Figure 13. Sample display for the lsqeth command showing details for devices
This screen shows the Linux lsqeth command with a resulting display.

Instructions: Attaching storage groups or tape links

Through the Storage section of the Partition Details task, you can attach one or more FICON, FCP, or NVMe storage groups or FCP tape links to an existing partition. FCP storage groups can be shared by multiple partitions, and multiple storage groups can be attached to one partition. FCP tape links also can be either shared by many partitions or dedicated to one. In contrast, only one partition can use an NVMe storage group at any given time; an NVMe storage group cannot be shared.

Note: In addition to using the Partition Details task to attach an FCP tape link, you can also attach a tape link to a selected partition through the Configure Storage task, when you use it to either create a new tape link or modify an existing one.

In the Partition Details task, the Storage section contains a Storage Groups table and a Tape Links table. To attach new storage groups or tape links to the partition, complete the following steps.

  1. Select the plus icon in the table toolbar to open the Attach Storage Groups or Attach Tape Links window.
  2. On the Attach Storage Groups window, select one or more storage groups listed in the Storage Groups table to attach to this partition.
    • The suggested practice is to select storage groups that are in the Complete fulfillment state, but you can select any storage group except for those with a fulfillment state of Incomplete, or those that are already attached to the maximum number of partitions. If you do select groups in states other than Complete, some storage might not be available for use immediately.
    • Use the additional information in the Storage Groups table, as necessary, to decide which storage groups to attach. For descriptions of the columns in the Storage Groups table, see the online help.

    When you have finished selecting storage groups to attach, select OK to close the Attach Storage Groups window.

  3. On the Attach Tape Links window, select one or more tape links listed in the table to attach to this partition.
    • The suggested practice is to select tape links that are in the Complete fulfillment state, but you can select any tape link except for those with a fulfillment state of Incomplete, or those that are already attached to the maximum number of partitions. If you do select links in states other than Complete, some storage might not be available for use when you start the partition.
    • Use the additional information in the table, as necessary, to decide which tape links to attach.

    When you have finished selecting tape links to attach, select OK to close the Attach Tape Links window.

  4. Check the entries for the storage groups or tape links that you selected, which are now displayed in the Storage Groups table or Tape Links table in the Storage section. If necessary, you can use the minus icon in the table toolbar to remove a storage group or tape link from the table.
  5. When you have finished, click OK to save the partition definition.

    If the partition is running, or when you restart a stopped partition, you might need to enter Linux commands to make any newly attached storage groups available to the operating system that the partition hosts. NVMe storage groups are automatically detected by the operating system, so you do not need to enter Linux commands to make that type of storage group available to the operating system. Similarly, the tape devices that are available through attached tape links are automatically detected by the operating system, so you do not need to enter Linux commands for tape devices either. The actions required for FCP or FICON storage groups depend on the type and fulfillment state, and whether the storage group contained the boot volume for the operating system.

    Note: If you issue the lscss command and the device number of the newly attached storage group is not listed, the device might be included in a list of devices to be ignored by Linux. If cio_ignore is active, the list is automatically adjusted to accommodate all devices that are configured on the HMC interface only when you reboot the operating system. To dynamically add the device, use cio_ignore -r to remove the device from the list, then set the device online.
    When attaching a storage group in Complete state when the partition is stopped
    • For an FCP storage group:
      • If the storage group contained the boot volume, the operating system brings online all of the HBAs for this storage group, and all volumes in the storage group are available. No action is required unless you have attached other storage groups.
      • If the storage group does not contain the boot volume, and the operating system is not configured to bring HBAs online automatically, you need to issue the chccwdev command to bring online all of the HBAs.
    • For a FICON storage group, the operating system brings online only the boot volume. You need to issue the chccwdev command to bring online all of the remaining volumes in the storage group that contains the boot volume, as well as the volumes in any other storage groups that you attached.
    When attaching a Complete storage group to a running partition, or attaching an unfulfilled storage group that becomes Complete as the partition is running
    • For an FCP storage group:
      • If adapters were assigned to HBAs while the partition is running, you need to use the chchp command to activate the channel paths for those new adapters.
      • To access the volumes in the storage group, you need to issue the chccwdev command to bring online all of the HBAs.
    • For a FICON storage group:
      • If the adapters connecting the storage group to the storage subsystem were assigned while the partition is running, use the chchp command to activate the channel paths for those new adapters.
      • All volumes are offline. You need to issue the chccwdev command to bring online all of the volumes in the storage group.
    To find the IDs that you need to use for the Linux commands, use the following tasks.
    • HBA device numbers are available in the Host Bus Adapters (HBA) table when you expand the storage group table entry in the Storage section of the Partition Details task.
    • Channel path IDs for FCP adapters are shown in the Host Bus Adapters (HBA) table when you expand the storage group table entry in the Storage section of the Partition Details task.
    • Channel path IDs for FICON adapters are shown on the ADAPTERS tab of the Storage Group details; open the Configure Storage task and select the storage group in the Storage Overview to open the Storage Group details page.
    • FICON volume device numbers are shown on the VOLUMES tab of the Storage Group details page; open the Configure Storage task and select the storage group in the Storage Overview to open the Storage Group details page.

Instructions: Detaching and reattaching an FCP storage group

When you detach an FCP storage group from a partition, DPM does not preserve the HBAs, device numbers, or backing adapters that were in use for that storage group. Consequently, if you reattach the storage group to the same partition, the device numbers and the backing adapters of the HBAs are not guaranteed to be the same as they were before the detachment. The same condition is true if you attach the FCP storage group to a new partition: the device numbers and the backing adapters of the HBAs are not guaranteed to be the same as they were when the storage group was attached to a different partition.

If the operating system image for the partition resides on a boot volume in the storage group that you reattach, the operating system might not start when the partition is restarted. (Operating systems that are started from a storage volume usually have a preconfigured device number and a path to the volume.) To avoid this situation, administrators must review the device numbers and the backing adapters of the HBAs, after reattaching the storage group and before restarting the partition. If necessary, the administrators must change the device number to match the preconfigured device number for the operating system, and make sure that the preconfigured device number is assigned to the backing adapter that was assigned to the HBA before the detachment.

Notes:
  • If the storage group that is being reattached contains the boot volume for the operating system, you must stop the partition before detaching and reattaching the storage group. Running workloads can be disrupted if you detach and reattach a storage group that contains boot volumes while the partition is active. (If a storage group contains only data volumes, you do not have to stop the partition.)
  • When you detach and reattach a FICON storage group, the device numbers of storage volumes do not change because they are associated with the storage group volumes.

Use the following instructions to detach an FCP storage group that contains a boot volume, and reattach it to the same partition.

  1. If the partition is active, use the Stop task to stop the partition.
  2. Open the Partition Details task for the partition.
    1. Go to the Boot section. If the Storage device (SAN) boot option is selected, and a boot volume in an FCP storage group is selected, note the name of the storage group.
    2. Go to the Storage section, and select the FCP storage group that contains the boot volume for the operating system.
      1. Expand the storage group table entry to show the Host Bus Adapters (HBA) table, and record the device number and the assigned adapter.
      2. In the Storage Group table toolbar, select the minus icon to detach the storage group.
  3. When you reattach the storage group, make sure that the partition is stopped and, if necessary, reopen the Partition Details task to the Storage section.
    1. In the Storage Group table toolbar, select the plus icon to open the Attach Storage Groups window.
    2. On the Attach Storage Groups window, select the storage group.
    3. Select OK to close the Attach Storage Groups window.
    4. Select and expand the entry for the storage group, which is listed in the Storage Groups table in the Storage section.
      1. Look for the adapter that you recorded before detaching the storage group. If it is listed, continue to the next step (check the device number for the HBA). Otherwise, complete the following steps:
        1. Select Change Adapters to open the FCP adapter assignment window.
        2. In the Assigned Adapters table, select an existing adapter, and select UNASSIGN.
        3. In the Adapter Candidates table, find the adapter that you recorded, and select ASSIGN.
        4. Select SAVE to save your changes and return to the Storage section of the Partition Details task.
      2. Check the device number for the HBA that is associated with the recorded adapter. If necessary, change the device number to match the preconfigured device number that the operating system uses (the device number that you recorded before detaching the storage group).
      3. Select Apply to save your changes.
    5. Go to the Boot section of the Partition Details task.
      1. Select Storage device (SAN) as the Boot from option.
      2. Use the radio button in the Select column to select the reattached FCP storage group that contains the boot volume for the operating system.
    6. Select OK to save your changes and close the Partition Details window.
  4. Use the Start task to restart the partition.

Instructions: Changing the adapters that are assigned to an FCP storage group

In the Configure Storage task, when you open the Storage Group details page for an FCP storage group, you can review the adapters assigned to a storage group and remove or replace them with other adapters that are available for use by a partition. However, if an FCP adapter is configured while the storage group is attached to an active partition, DPM cannot detect and list the new adapter as available for use by any partition.

To make sure that you can choose a new adapter from a complete list of available adapters, perform the following steps on the HMC.

  1. Open the Configure Storage task to the Storage Overview page, and select the table row for the FCP storage group. The Storage Details page opens.
  2. Select the PARTITIONS tab to display a list of the partitions to which this storage group is attached. If any partitions are listed as Active, use the Stop task to stop them. After all of the active partitions are stopped, continue to the next step.
  3. Select the Connection Report icon to open the Connection Report page for the FCP storage group. On the Connection Report page, select the Update report icon (This icon is a circular arrow, pointing clockwise) to start a new background check of the available connections for the storage group. When the check is complete, the Report Date field is updated.
  4. After the background check completes, verify that the new adapter is listed in the Mainframe section of the connection report, and that no errors are associated with the adapter. Close the Connection Report page.
  5. On the PARTITIONS tab, expand the table row for one of the partition for which you want to use the new adapter, and select Change Adapter. On the FCP adapter assignment window, complete the following steps.
    1. Review the entries in the Assigned Adapters table and, if necessary, select an existing adapter, and select UNASSIGN to remove it from the table.
    2. In the Adapter Candidates table, find the table entry for the new adapter.
    3. In the adapter table entry, select ASSIGN to assign the new adapter.
    4. Select SAVE to return to the Storage Group details page.
    Repeat these steps for each partition for which you want to use the new adapter.
  6. Check the fulfillment state of the storage group. When the state is Complete, use the Start task to restart the partitions.

Instructions: Changing the adapters that are assigned to an FCP tape link

In the Configure Storage task, when you open the Tape Link details page for an FCP tape link, you can select the ADAPTERS tab to review the adapters that are assigned to the tape link. To change the adapters for a tape link, select Modify to open the Tape Link details page in Modification mode. Modification mode is indicated by a large blue bar that contains the Modification label, plus the CANCEL and SAVE buttons. In this mode, you can add or delete adapters only by changing the number of connecting paths. Remember that changes to this connectivity setting have an impact on bandwidth, performance, and redundancy. You also can replace currently assigned adapters with other available adapters, and resolve adapter mismatches when the fulfillment state of the tape link is Pending with mismatches.

When you save your changes, the fulfillment state of the tape link changes to Pending, and DPM automatically generates a request that you can send to one or more storage administrators; this email includes zoning instructions for the storage administrators to follow to fulfill your request.

The following topics describe the methods for changing the adapters for a tape link, and factors that you need to consider when using each method.

Modify the number of connecting paths
Changes that you make through the Number of connecting paths slider, text entry field, or spin button are reflected in the adapters table. The changes vary, depending on whether you are decreasing the number of paths, increasing the number of paths, or both, during a single modification session.
Only decrease the number of connecting paths
When you decrease the number of paths, DPM automatically grays out the appropriate number of adapter rows from the table, selecting the adapters to remove in the following order.
  1. Adapters to be selected by the storage administrator (placeholder rows) that DPM assigned or that you selected to replace assigned adapters.
  2. Unzoned adapters that are already assigned to the tape link.
  3. Zoned (Matching) adapters that are already assigned to the tape link.
  4. Unzoned adapters that you selected to replace assigned adapters.
  5. Zoned (Matching) adapters that you selected to replace assigned adapters.
Each adapter that DPM selects for removal is marked with a recover icon (This icon consists of an arrow curving counterclockwise around a solid dot, with the arrowhead pointing up) to the right of the table row. If you prefer to remove different adapters, select the recover icon for any marked adapter, and the table display changes to show each adapter row with a trash can icon, so you can select which assigned adapters to delete. An inline message tells you how many adapters you need to select for deletion. When you click the trash can icon, DPM marks the adapter to be removed with one of the following marks, to the left of the table row:
  • A red dot to indicate the adapter that was most recently selected for removal.
  • A warning icon (This icon consist of a solid yellow triangle containing a black exclamation point), when this change is disruptive to active partitions that are using the tape link.
Only increase the number of connecting paths
When you increase the number of connecting paths, DPM adjusts the Adapters table by adding the corresponding number of table rows; for example, if you increase the number of paths by 2, the table contains two new table rows.
  • DPM preselects adapters that are connected to the tape library already, and that provide optimal redundancy. Optimal redundancy for adapters is based on the following factors, which are listed in priority order from highest to lowest: on the location in the I/O drawers, on the drawer domain, on the current allocation, and on the connection to SAN fabrics.
  • If the total number of preselected adapters is less than the number of connecting paths that you selected, placeholder rows represent the remaining number of adapters for the storage administrator to assign. If you do not supply a specific adapter for a placeholder row, the storage administrator selects the adapter for you, as part of fulfilling your modification request.

If more adapters are available for selection, you can select the exchange icon (This icon consists of two arrows, one on top of the other, with the top arrow pointing to the left and the bottom arrow pointing to the right) to replace a preselected adapter.

Increase and decrease the number of paths in a single modification session
If you increase and decrease the number of connecting paths within a single modification session, DPM automatically adds or removes Adapter table rows in a specific order.
  • When you increase the number of connecting paths, DPM automatically adds the appropriate number of adapters, preselecting them in the following order.
    1. Adapters that you already deleted in this modification session, if any.
    2. Zoned (Matching) adapters that were not assigned previously to this tape link.
    3. Adapters that were previously assigned to this tape link, but were replaced through the exchange dialog.
    4. Adapters to be selected by the storage administrator (placeholder rows).
  • When you decrease the number of connecting paths, DPM automatically removes the appropriate number of adapter rows from the table, selecting the adapters to remove in the following order.
    1. Adapters to be selected by the storage administrator (placeholder rows) if you increased the paths in this modification session.
    2. Zoned (Matching) adapters that DPM preselected if you increased the paths in this modification session.
    3. Remaining placeholder rows, if any, including placeholder rows that DPM assigned or that you selected to replace assigned adapters.
    4. Unzoned adapters that are already assigned to the tape link.
    5. Zoned (Matching) adapters that are already assigned to the tape link.
    6. Unzoned adapters that you selected to replace assigned adapters.
    7. Zoned (Matching) adapters that you selected to replace assigned adapters.
Replace assigned adapters
To replace an assigned adapter (or add an adapter to a placeholder row), complete the following steps. For the best results, try to assign adapters that reside in different system I/O drawers and in different domains; that are not on the same card; and that are connected to different fabrics. Inline messages provide warnings if the selected adapters do not meet these criteria.
  1. Select the exchange icon (This icon consists of two arrows, one on top of the other, with the top arrow pointing to the left and the bottom arrow pointing to the right). A dialog opens and displays information about the assigned adapter or placeholder row that you want to exchange, and available adapters to replace it.
  2. If you want a storage administrator to select an adapter for you, select Adapter to be assigned by the storage administrator under the Available adapters heading. Otherwise, use the information in the Available adapters table to select a replacement adapter. Note that any adapter with an existing error condition is marked with an incomplete icon (This icon consists of a solid red circle with a white exclamation point inside). The suggested practice is to avoid selecting such adapters.
    MATCH
    If an adapter is already connected to the tape library that you are using for this tape link, this column contains the label Matching in the adapter row. Otherwise, this column is empty.
    NAME
    Specifies the name of the FCP adapter. DPM assigns a default adapter name in the form adapter_type pchid partial_location, which can help you determine whether you are selecting adapters that, for optimal redundancy, reside in different drawers and different domains. For example, in the sample default name FCP 0171 Z22B-11:
    • FCP is the type.
    • 0171 is the physical channel path identifier (PCHID).
    • Z22B is the plug location of the I/O drawer, with the first letter denoting the frame in which the drawer resides.
    • 11 is the slot in the drawer in which the adapter is plugged.

    For rack mount configurations, the partial_location section of the default name begins with AIOx, where A is the frame identifier, and x is the number of the I/O drawer.

    FABRIC ID
    Displays the worldwide name (WWN) of the uplink Fibre Channel switch. For optimal redundancy, use this value to select adapters that are connected to different fabrics.
    ADAPTER ID
    Specifies the physical channel ID of the adapter; this ID is a four-character hexadecimal number.
    TYPE
    Indicates the type of adapter card, which varies depending on the adapter cards that the system supports. Valid values include specific FICON Express® adapter names.
    LOCATION
    Specifies the physical location of the adapter in the I/O drawer of the system.
    ALLOCATION
    Indicates the percentage of host bus adapters (HBAs) that are currently allocated to this adapter, shown in a bar graph and in numeric format. The displayed percentage includes HBAs only for started and reserved partitions. If the percentage is high (for example, 90%), consider assigning a different adapter.
  3. Select Replace to save your selection and close the dialog window. On the ADAPTERS tab, the table row for the adapter that you just selected is marked with one of the following icons.
    • A pending icon (This icon is a blank white clock with a yellow outline and solid yellow wedge from positions 9 to 12) indicates that zoning is required before the fulfillment state of the tape link can change to Complete.
    • An incomplete icon (This icon consists of a solid red circle with a white exclamation point inside) indicates an existing error condition for the adapter. The suggested practice is to replace such an adapters with different ones.
    • A warning icon (This icon consist of a solid yellow triangle containing a black exclamation point), when this change is disruptive to active partitions that are using the tape link.
  4. Repeat these steps, as necessary, to replace any more assigned adapters.
Resolve pending mismatches
When the fulfillment state of the tape link is Pending with mismatches, the ADAPTERS tab display contains three separate sections through which you can change the number of connecting paths, view and delete unrequested and zoned adapters, or view and replace assigned adapters. You can use any one of those three actions, or a combination of them, to resolve the pending mismatches.
For example, suppose that you requested a tape link with two connecting paths, and you selected two specific, available adapters for your tape link. If a third adapter is already zoned for the tape library that is selected for your tape link, the fulfillment state of the tape link is Pending with mismatches because three zoned adapters exceeds the requested number of two connecting paths. On the ADAPTERS tab, the third adapter is listed in the table of Unrequested and zoned adapters, which is displayed above the assigned adapters table. Through Modification mode, you can resolve this mismatch through one of the following actions.
  • Increase the number of connecting paths to 3. In this case, the unrequested adapter becomes an assigned adapter, and no zoning changes are required.
  • Select the unrequested adapter for deletion. In this case, when you save your changes, the storage administrator receives zoning instructions to remove the host WWPN for this unrequested adapter.
  • Replace one of the assigned adapters with the unrequested adapter. This action can be useful if one of the assigned adapters is pending (not zoned yet).