HP-UX 11i v3 Dynamic nPartitions - Features and Configuration Recommendations

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HP-UX 11i v3 Dynamic nPartitions

Features and configuration recommendations

Table of Contents

Introduction...................................................................................................................................3

nPartitions Background....................................................................................................................3

Dynamic nPartitions operations.........................................................................................................3

Cell online activation...................................................................................................................3

Cell online deactivation................................................................................................................3

Base cells and floating cells ..........................................................................................................4

Dynamic nPartitions commands.........................................................................................................4

I/O chassis................................................................................................................................4

Scenarios for Dynamic nPartitions......................................................................................................5

Adding capacity to an nPartition....................................................................................................5

Shifting floating capacity to meet demand peaks..............................................................................5

Temporary removal of a partition...................................................................................................6

Replacement of hardware.............................................................................................................6

Configuration recommendations for Dynamic nPartitions........................................................................7

Minimum amount of memory on base cells ......................................................................................7

I/O chassis................................................................................................................................8

Duration of Dynamic nPartitions operations......................................................................................8

Sensitivity to operating system workload .........................................................................................8

Current limits and conditions.............................................................................................................9

Rollout of Dynamic nPartitions functionality in HP-UX 11i v3................................................................9

Dynamic nPartitions, virtual partitions, and Integrity Virtual Machines...................................................9

Requirement to reset Workload Manager........................................................................................9

Integration with instant capacity.....................................................................................................9

Interaction with processor sets.....................................................................................................10

Cell reset recovery time..............................................................................................................10

Summary.....................................................................................................................................10

Illustrated example of online cell migration........................................................................................11

Command sequences for Dynamic nPartitions scenarios......................................................................14

Cell replacement.......................................................................................................................14

Summary of content (22 pages)

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HP-UX 11i v3 Dynamic nPartitions Features and configuration recommendations Table of Contents Introduction ................................................................................................................................... 3 nPartitions Background .................................................................................................................... 3 Dynamic nPartitions operations .................................................................................................
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Cell migration........................................................................................................................... 14 Transcript of cell migration operation ............................................................................................... 15 What could possibly go wrong?...................................................................................................... 19 Glossary .........................................................................................
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Introduction This white paper introduces the Dynamic nPartitions feature that will debut with HP-UX 11i v3 Update 1. The nPartitions Background section summarizes the properties of nPartitions on HP-UX 11i before the update. The Dynamic nPartitions operations section explains the operations that make nPartitions dynamic. The Dynamic nPartitions commands section illustrates the invocation of the new Dynamic nPartitions commands.
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Base cells and floating cells A cell is eligible for online deactivation if and only if it is designated as a floating cell. Any cell not specifically designated as a floating cell is a base cell. HP-UX before 11i v3 included support for base cells only. A base cell cannot be online deactivated. The system administrator designates a cell as a base cell or floating cell using the nPartition commands. Designation as a floating cell has two important implications.
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If a cell with I/O (an I/O chassis or core I/O or both) is online activated, then the I/O is also available to the partition. However, the I/O is not automatically activated: a separate command, olrad, is required to activate the I/O. The command for I/O chassis activation is olrad –A -s cell_hardware_path where the I/O chassis connected to the cell specified by cell_hardware_path is online activated. The cell_hardware_path must be a global slot number.
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Figure 1 illustrates a configuration appropriate for this scenario. Suppose a server complex consisting of eight cells were partitioned with cells 0 and 1 as base cells in partition 0; cells 2 and 3 as base cells in partition 1; and cells 4 and 5 as base cells in partition 2. Cells 6 and 7 are floating cells that can be assigned to the partition that needs them most at the time. Figure 1.
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Only floating cells are available for this type of replacement. You must reboot the partition to replace a base cell. Also, this is not the same as the "online replacement" available for PCI cards, which involves a temporary suspension of access and replacement with identical hardware configured into the identical state. Configuration recommendations for Dynamic nPartitions This section contains guidelines for optimizing the benefits of Dynamic nPartitions.
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I/O chassis Many workloads are CPU-bound or memory-bound. When using cell online activation to increase the capacity of a partition running such a workload, an I/O chassis does not need to be attached to the cell. In some cases, I/O resources can be considered private to an application and to the partition that hosts it. An example would be a SCSI controller that connects to disks containing application data.
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sessions, or similar measures. Various capacity planning tools are available to match workloads to hardware resource levels. These considerations apply particularly to the Oracle Database products. If the memory allocated to the Oracle Database is based on the full complement of cells in the partition, then the system will not perform well if cells were to be deactivated.
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Interaction with processor sets Dynamic nPartitions is fully integrated with processor sets. If the attributes of a processor set are established so that it is not allowed to become empty, then the last SPU in that processor set cannot be online deactivated. If a cell online deactivation operation would cause the processor set to become empty, then that operation will not complete successfully. Cell reset recovery time When a cell is deactivated online, it is reset to prepare for its next use.
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Illustrated example of online cell migration This example of using Dynamic nPartitions operations to migrate a cell from one partition to another features a server complex containing eight cells. The complex is partitioned with cells 0, 1, and 2 in nPartition 0. Cells 3, 4, 5, 6, and 7 are in nPartition 1. Each partition runs a separate instance of the HP-UX operating system. Figure 2 shows the initial configuration. Figure 2.
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Figure 3. HP-UX instance 0 HP-UX instance 1 nPartition 0 nPartition 1 cell 0 cell 1 cell 2 cell 3 cell 4 cell 5 cell 6 cell 7 base cell float cell float cell float cell base cell base cell base cell base cell Cell 2 is still assigned to partition 0, but it is inactive. Now, the cell can be unassigned from partition 0 with the command parmodify –p 0 -d 2 Figure 4.
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Figure 5. HP-UX instance 0 HP-UX instance 1 nPartition 0 nPartition 1 cell 0 cell 1 cell 2 cell 3 cell 4 cell 5 cell 6 cell 7 base cell float cell float cell float cell base cell base cell base cell base cell Note that cell 2 is assigned to partition 1, but it is inactive, so its resources are not being used by HPUX instance 1. The cell can be online activated with the command parolrad -a 2 Figure 6.
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Command sequences for Dynamic nPartitions scenarios This section shows representative command sequences to perform common Dynamic nPartitions operations. Cell replacement The following command sequence could be used if it is desired to replace or perform hardware maintenance upon the cell whose global slot number is S. It is assumed that the target cell is a floating cell and it has an active I/O chassis connected to it.
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The system name of the HP-UX instance running in partition q is "remote_system" and the userid "administrator" has the required privilege. parolrad -d S parmodify -p p -d S parmodify -p q -a S:floating:y:float:100% Is necessary to wait until the cell has completed its power on sequence. parolrad -a S -u administrator: -g remote_system The parolrad command will prompt for the password associated with the administrator userid. Then, the cell migration operation will complete.
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[Cell] CPU OK/ Hardware Actual Deconf/ Location Usage Max ========== ============ ======= cab0,cell0 Active Core 8/0/8 cab0,cell1 Active Core 8/0/8 cab0,cell2 Inactive 8/0/8 cab0,cell3 Active Base 8/0/8 Memory (GB) OK/ Deconf ========= 8.0/0.0 8.0/0.0 8.0/0.0 8.0/0.
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Online operation has completed successfully. [par0]# olrad -A -s 2 Chassis Add operation in progress... [ NOTE: The chassis add operation may take a few minutes to complete on large configurations. Killing or otherwise aborting this olrad command may not cancel the Chassis Add operation.
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cab0,cell2 Active Float 8/0/8 cab0,cell3 Active Base 8/0/8 8.0/0.0 8.0/0.0 cab8,bay0,chassis0 yes cab8,bay0,chassis1 yes Notes: * = Cell has no interleaved memory. [par0]# /locinfo2 --- System wide locality info: --index ldom physid type total free 0 0 0 CLM 3.93G 3.36G 1 1 3 CLM 3.94G 3.53G 2 2 2 CLM 7.94G 7.55G 3 -1 -1 ILV 8.00G 6.24G --------23.81G 20.68G float 0 0 7.55G 0 ----7.55G yes 0 yes 0 used 587.37M 412.05M 398.78M 1.76G ----3.
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What could possibly go wrong? Dynamic nPartitions commands return a message if the operation cannot proceed as intended. The following table gives some troubleshooting hints. Message The cell shall be assigned to the local (target) nPar. The cell shall be at BIB (completed POST). The Use On Next Boot flag shall be set to true for the target cell. There shall not be a cell OL* operation already in progress on the local (target) nPar. The OS on the target nPar shall support cell online operations.
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Glossary Term Assigned and unassigned cells Definition Each cell in a server complex either is assigned to one of the nPartitions in the complex, or it is unassigned and thus is not used by any of the nPartitions. If an I/O chassis is attached to an unassigned cell, then the chassis likewise is not assigned to an nPartition. Cells that are unassigned are considered to be available resources; they are free to be assigned to any of the existing nPartitions, or can be used to create new nPartitions.
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Cell-based HP servers and Dynamic nPartitions Cell-based HP servers that support HP-UX 11i v3 Dynamic nPartitions operations: Cell capacity Server model Two-cell Servers HP 9000 rp7420 Server HP 9000 rp7440 Server HP Integrity rx7620 Server HP Integrity rx7640 Server Four-cell Servers HP 9000 rp8420 Server HP 9000 rp8440 Server HP Integrity rx8620 Server HP Integrity rx8640 Server HP 9000 Superdome Servers HP 9000 Superdome Server (PA 8800 and PA 8900) HP 9000 Superdome Server with sx2000 HP Integri
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For more information http://www.hp.com/go/hpux11iv3 http://www.docs.hp.com/en/5991-1247B/ for the nPartition Administrator's Guide. http://docs.hp.com/en/PARMGR2/ for a description of the Partition Manager product. http://docs.hp.com/en/SFWM1/index.html for the firmware versions to support Dynamic nPartitions. © 2008 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.