Myth Busting Goes Virtual. Todd Mera - [email protected] Systems Engineer | Quest Software Server Virtualization Management Group (541) 314-3302 . Mattias Sundling Evangelist, Quest Software Eric Sloof VMware Certified Instructor, NTPRO.NL. Just in case you are curious…. - PowerPoint PPT Presentation
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Just in case you are curious…• 2010 – With the second launch of the SpaceX Dragon, SpaceX
becomes the first privately held company to successfully launch, orbit and recover a spacecraft.
• 1995 - The Grateful Dead announced they were breaking up after 30 years of making music. The news came four months after the death of lead guitarist Jerry Garcia
• 1886 – Diego Rivera, Mexican painter (d. 1957)
• Eli Whitney (December 8, 1765 – January 8, 1825) was an American inventor best known for inventing the cotton gin
• 1966 – Sinéad O'Connor, Irish musician
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Introduction• vSphere evolves with every release.• Things that used to be true aren't true anymore.• Engage in virtualization communities and social media to get up
to speed.
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Agenda/Myths
1) iSCSI RDMs have superior performance over VMFS.2) CBT causes significant overhead on your VMs.3) Resource Pools should always be used to categorize and allocate
resources to VMs.4) LSI SCSI is always better than Paravirtual SCSI.
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Myth 1:iSCSI RDMs have superior performance over VMFS
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What is a RDM
• A RDM is a symbolic link. • When a LUN is opened for access, the mapping file is
read to obtain the reference to the raw LUN.• Thereafter, reads and writes go directly to the raw LUN
rather than going through the mapping file.
RAW LUN
VMFS volume
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VMkernel and Storage
• Physical Compatibility mode RDM
• Virtual mode RDM
• Regular VMDK on VMFS
• Logical device IO scheduler
• vStorage APIs
• Adapter IO schedulerand Linux emulation
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The iSCSI Laboratory• Iomega StorCenter px6-300d with 6 SATA
7200 Disks
• Windows 2008 R24096 MB – 1 vCPUHardware Version 8
• Paravirtual SCSI– Introduced in vSphere 4, improved in vSphere 4.1– Designed for high performance (+12%)– Requires less resources on vSphere Host (-18% CPU)
– Supports only Win 2003+, RHEL5+, SUSE Linux Enterprise 11 SP1+, Ubuntu 10.04 +, Linux 2.6.33+
– Virtual HW v7+
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Test Result LSI Logic vs. PVSCSILSI Logic PVSCSI
Host CPU utilization90MB/s – 60 000 IOPS
• Very similar disk throughput
• Lower Host CPU Utilization for PVSCSI
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PVSCSI Limitations• PVSCSI controllers have the following limitations:
– Disks on PVSCSI controllers might not experience performance gains if they have snapshots or if memory on the ESXi host is over committed.
– MSCS clusters are not supported.– PVSCSI controllers do not support boot disks, the disk that contains
the system software, on Red Hat Linux 5 virtual machines. Attach the boot disk to the virtual machine by using any of the other supported controller types.
Myth Busted• PVSCSI is equal or faster than LSI SCSI• PVSCSI requires less Host resources• Used to have more limitations • PVSCSI is better in all ways so why aren´t we
using it on all supported VMs?• Takes time to change behaviour
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Summary• VMFS is better than RDMs• CBT has very little overhead• Do your math when using sibling RPs• PVSCSI is equal or faster and requires less resources than LSI