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 March 2006. Virtualization solutions help organizations pool, share and manage IT resources across multiple workloads. The promise of virtualization technology is that it allows you to optimize IT utilization while increasing agility. In order to be effective, virtualization technologies need to be seamlessly integrated into the IT infrastructure, with a single point of management to reduce complexity and improve overall efficiency.
When evaluating IBM virtualization capabilities, here are some facts that you should know.
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Fact 1: The IBM Virtual I/O Server is a single point of failure[1] and requires a dedicated LPAR increasing the virtualization overhead[2]. |
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The IBM Virtual I/O Server can be made redundant by running a second instance of it in another partition. However, if you use the Integrated Virtualization Manager (IVM), it is not possible to have a redundant virtual I/O server and therefore it’s impossible to eliminate the single point of failure.3
Processor resources dedicated to the virtual I/O server add to the virtualization overhead. IBM recommends a dedicated processor allocated when when performance is a concern.4 Therefore dedicated resources must be allocated to the virtual I/O server and cannot be made available for customer workloads.
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Fact 2: IBM micropartitions have a performance overhead that increases as the number of partitions increases.[5] |
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By contrast, hardware-based partitions with dedicated hardware resources, such as HP’s nPartitions, do not come with a performance overhead penalty.6
Therefore the aggregate performance of a hard-partitioned HP Superdome can actually go up as the system is partitioned.
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Fact 3: IBM eServer p5 servers do not support hard partitions with full electrical isolation.[7] |
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HP nPartitions, on the other hand, offer a higher level of fault isolation than does a soft partition approach like IBM‘s LPARs.8 Each cell-based HP Integrity server can be partitioned into separate fault-isolated nPartitions.
Lack of electrical isolation between IBM LPARs may cause some users to cluster mission-critical applications in partitions on a separate backup server.
IBM states that, “By itself, LPAR does not provide a significant availability increase.”9
Unlike IBM LPARs, fully isolated hard partitions such as HP nPartitions offer electrical isolation and cell board granularity, allowing you to service one partition while others are online.10 IBM references show that a full system shutdown (not just of the affected partition) is required to physically remove and replace a processor.11
For more about HP partitions, see: http://www.hp.com/go/partitions.
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Fact 4: IBM’s POWER virtualization technology is made up of individual pieces with restrictions that limit the amount of integration between them. |
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A few resulting limitations are outlined below.
IBM Partition Load Manager (PLM) restrictions:
• IBM’s PLM cannot manage the IBM Virtual I/O server (VIOS).12
• The IBM PLM does not support a redundant Hardware Management Console (HMC).12
• The IBM PLM does not support systems managed by Integrated Virtualization Manager (IVM).12
IBM Integrated Virtualization Manager (IVM) restrictions:
• The IVM and HMC are incompatible.13
• The IVM is not supported on the p5 570, 575, 590 or 595.13
• When using the IVM, only the VIOS is dynamic. Other LPARs (production LPARs) are not dynamic.13
• When using the IVM all I /O must be virtualized. This means that production LPARs can’t have dedicated physical I/O .13
• It is not possible to have a redundant VIOS. 14 (See Fact 1 above: The only way to prevent the VIOS from being a single point of failure is to have redundant partitions, which is something precluded by the IVM.)
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Fact 5: IBM states, “IBM Director currently lacks the functionality for properly managing AIX servers".[15] |
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What this means is that you will need to use multiple IBM management tools to mange a heterogeneous datacenter.16
HP Systems Insight Manager (HP SIM), by comparison, is the foundation for HP's unified infrastructure management strategy. It provides hardware level management for HP ProLiant, Integrity, and HP 9000 servers; HP BladeSystems; and HP StorageWorks MSA, EVA, and XP storage arrays. Beyond system management, HP SIM provides support for the HP Virtual Server Environment (VSE), enabling integrated control for HP’s virtualization technologies.
For more information on HP Systems Insight Manager, see: http://www.hp.com/go/hpsim.
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Fact 6: The minimum charge for IBM’s on/off capacity on demand is one day, regardless of whether the processor activation was for a much shorter period of time.[17] |
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When you pre-pay for 30 processor days with HP’s Temporary Instant Capacity (TiCAP), your active processor time is measured in much more granular 30 minute slices.18
To learn more about the advantages of HP virtualization solutions, see: http://www.hp.com/go/virtualization.
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1 IBM Redbook " Advanced POWER Virtualization on IBM system p5“ Dec, 2005, page 255, http://publib-b.boulder.ibm.com/abstracts/sg247940.html?Open, “we recommend using two Virtual I/O Servers at least for production partitions (not necessary for stand-by partitions), so the Virtual I/O Server does not become a single point of failure (SPOF).”
2 IBM Redbook " Advanced POWER Virtualization on IBM system p5“ Dec, 2005, section 4.2.1, http://publib-b.boulder.ibm.com/abstracts/sg247940.html?Open
3 IBM Redbook “System p5 505 Express Techniocal Overiew and Introduction”, http://www.redbooks.ibm.com/redpapers/pdfs/redp4079.pdf, page 35
4 IBM Redbook " Advanced POWER Virtualization on IBM system p5“ Dec, 2005, section 4.2.1, http://publib-b.boulder.ibm.com/abstracts/sg247940.html?Open
5 ITG Whitepaper “Value Proposition for IBM eServer p5- Cost/Benefit Case for POWER5 Micro-Partitioning”, “Like other virtualization technologies, MPs [micropartitions] generate system overhead, which increases in proportion to the number of MPs running on a single physical platform.” http://www-03.ibm.com/servers/eserver/pseries/library/consult/itg_valueprop.pdf
6 http://h71028.www7.hp.com/ERC/downloads/5982-9141EN.pdf “Guaranteed performance and throughput: Hard partitions are used when batch workloads or online applications require dedicated resources in order to perform according to service-level objectives (SLOs).”
7 IBM Whitepaper, “IBM p5: A Highly Available Design for Business-Critical Applications, “http://www-03.ibm.com/systems/p/hardware/whitepapers/power5_ras.pdf, page 29
8 Illuminata report, http://www-1.ibm.com/servers/eserver/pseries/library/consult/illuminata_p5.pdf, pages 3 -4
9 http://www-1.ibm.com/servers/eserver/pseries/lpar/
10http://h71028.www7.hp.com/enterprise/cache/4282-0-0-0-121.aspx
11 IBM reference “System p5 and i5, eServer p5 and i5 and OpenPower Server Provider Information, Beginning problem analysis and isolation”, page 271, http://publib.boulder.ibm.com/infocenter/eserver/v1r3s/topic/iphau/iphau.pdf
12 IBM Redbook, “Advanced POWER Virtualization” Section 7.5, http://www.redbooks.ibm.com/redpieces/pdfs/sg247940.pdf
13 IBM Redbook “Virtual I/O Server Integrated Virtualization Manager”, http://www.redbooks.ibm.com/redpapers/pdfs/redp4061.pdf
14 IBM Redbook “System p5 505 Express Techniocal Overiew and Introduction”, http://www.redbooks.ibm.com/redpapers/pdfs/redp4079.pdf, page 35
15 IBM Whitepaper, “Managing IBM eServer p5 and pSeries servers and IBM eServer BladeCenter JS20. IBM Director vs Cluster Systems Management”, page 16. http://www-03.ibm.com/servers/eserver/pseries/hardware/whitepapers/director_csm.pdf
16 IBM Whitepaper, “Managing IBM eServer p5 and pSeries servers and IBM eServer BladeCenter JS20. IBM Director vs Cluster Systems Management”, page 16. http://www-03.ibm.com/servers/eserver/pseries/hardware/whitepapers/director_csm.pdf
17 http://www-03.ibm.com/servers/eserver/pseries/ondemand/cod/types.html#two, “Increments of usage are measured in Processor Days, and the minimum usage is one day per activated processor.”
18 http://docs.hp.com/en/B9073-90081/B9073-90081.pdf
Intel and Itanium are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries. Microsoft and Windows are U.S. registered trademarks of Microsoft Corporation. UNIX is a registered trademark of The Open Group. Linux is a U.S. registered trademark of Linus Torvalds.
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