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VSP3067 Mythbusters Goes Virtual

VSP3067 Mythbusters Goes Virtual. Name, Title, Company. Mythbusters Goes Virtual . Eric Sloof VMware Certified Instructor, NTPRO.NL. Mattias Sundling Evangelist, Quest Software. Introduction. vSphere evolves with every release. Things that used to be true aren't true anymore.

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VSP3067 Mythbusters Goes Virtual

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  1. VSP3067Mythbusters Goes Virtual Name, Title, Company

  2. Mythbusters Goes Virtual Eric Sloof VMware Certified Instructor, NTPRO.NL MattiasSundling Evangelist, Quest Software

  3. 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.

  4. Agenda/Myths • iSCSI RDMs have superior performance over VMFS. • CBT causes significant overhead on your VMs. • Resource Pools should always be used to categorize and allocate resources to VMs. • LSI SCSI is always better than ParavirtualSCSI.

  5. Myth 1:iSCSI RDMs have superior performance over VMFS

  6. 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

  7. 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

  8. The iSCSI Laboratory • Iomega StorCenter px6-300d with 6 SATA 7200 Disks • Windows 2008 R24096 MB – 1 vCPUHardware Version 8 • VMware vSphere 5 • Single Intel 1GB Ethernet • Cisco 2960 switchMTU Size 1500

  9. Results Passmark PerformanceTest • RDM Physical • RDM Virtual • VMDK on VMFS • Microsoft software ISCSI initiator

  10. Myth Busted • 1 Gigabit/sec (Gbps) = 112.16 MB/s. • Use VMFS datastores whenever possible. • VMFS is optimized for storing and accessing large files. Only Use RDMs if your VM • is performing SAN snapshotting. • is clustered to a physical machine using MSCS. • has large amounts of data (64 TB) that you do not want to convert into a VMDK (2 TB).

  11. Myth 2:CBT causes significant overhead on your VMs

  12. What is CBT? • Driver inside VMkernel • Identifies change blocks within virtual disks • Block size based on VMDK size • Backup window and host resources significantly reduced • Requirements: vSphere4+ and Virtual HW v7+ • Limitations: pRDM, iSCSI within VM • Enable through vCenter or backup application CBT Driver

  13. CBT overhead • Memory • Max 256 KB / Disk (2TB) • 0.125 KB / GB VMDK • CPU • Turning on a bit in bitmap when an I/O request completes • Storage • Space • .ctk file 0,5 MB /10 GB VMDK • I/O • Every time disk gets closed, change tracking info written to disk

  14. Test/Result • Very little overhead CPU, Mem, Storage • Could not measure it, except .ctk file • No negative impact on disk I/O CBT Enabled CBT Disabled

  15. Myth Busted • CBT overhead is very small • Backup window and host resources reduced significant • Always use CBT if your backup solution supports it

  16. Myth 3:Resource Pools should always be used to categorize and allocate resources to VMs

  17. Resource Settings • CPU – Shares, Reservation, Limit. • Memory – Shares, Reservation, Limit. vApp Resource Pool VM

  18. Sibling CPU Shares Value • vApp = 4000 • Resource Pool= 4000 • VM = number of vCPU * 1000

  19. Sibling Memory Shares Value • vApp = 163840 • Resource Pool = 163840 • VM = Mem MB * 10

  20. The Laboratory RP 4000 Shares 6 Ghz RP 4000 Shares 6 Ghz vApp 4000 Shares 6 Ghz VM 4000 Shares 6 Ghz 6 Ghz 0,75 Ghz 0.5 Ghz 1.5 Ghz Root Resource Pool 24 Ghz 6 Ghz 6 Ghz 6 Ghz 6 Ghz

  21. Myth Busted If you want to • use Resource Pools, do your math! • group VMs in a container use the blue folders! • have apple (VM) and orange (vApp) siblings take care of them!

  22. Myth 4:LSI Logic SCSI is always better than PVSCSI

  23. What is PVSCSI? • Paravirtual SCSI • Introduced in vSphere 4, improved in vSphere 4.1 • Designed for high performance (+12%) • Requires less resources on vSphere Host (-18%) • Supports only Win 2003+, RHEL5+, SUSE Linux Enterprise 11 SP1+, Ubuntu 10.04 +, Linux 2.6.33+ • Virtual HW v7+

  24. Test Result LSI Logic vs. PVSCSI LSI Logic PVSCSI • Very similar disk throughput • Lower Host CPU Utilization for PVSCSI Host CPU utilization 90MB/s – 60 000 IOPS

  25. 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

  26. 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 SCSIBUT…

  27. References • CBT • https://www.vmware.com/support/developer/vddk/vadp_vsphere_backup12.pdf • PVSCSI • http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1017652 • http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1010398 • http://blogs.vmware.com/performance/2009/05/350000-io-operations-per-second-one-vsphere-host-with-30-efds.html • http://www.vmware.com/pdf/vsp_4_pvscsi_perf.pdf • http://www.vmware.com/pdf/Perf_Best_Practices_vSphere4.1.pdf

  28. Questions? Eric Sloof VMware Certified Instructor, NTPRO.NL esloof@ntpro.nl, @esloof Mattias Sundling Evangelist, Quest Software mattias.sundling@quest.com, @msundling

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