Does symmetrix dmx3 vs rdm physical mode vs vmware. Raw device mapping allows you to migrate a virtual machine with vmotion. Adding and sharing rdm disk to multiple vms in vmware step. Oracle rac and vmware raw device mapping rdm to be, or not to be famous words from william shakespeares play hamlet. Diagram of our single vmotion test, where we migrated the vm from host a to host b. Below table provides some of the important 11 differences between rdm virtual and physical compatibility mode. Vcp 6 study note vm migration cold, vmotion, svmotion, evc the added value for a server to be virtualized in a vsphere environment is the agility to move itself across physical environment with near zero downtime. The rdm pointer files are essentially nothing in size and shouldnt need space.
The new features available with vsphere 4 and even more with vsphere 5 make less and less sense to use rdm or at least they reduce a lot the reasons and the scenarios why they should be used. Physical mode specifies minimal scsi virtualization of the mapped device, allowing the greatest flexibility for san management software. I know i can probably mount a second rdm and do some kind of disk copy within the guest os, but i thought it might be faster to try to migrate it using native utilities. New vmware position on vmotion of rdm luns with oracle. I recently had a colleague contact me with a question about raw device mappings rdms and storage vmotion. This due in large part to vmwares concerted effort starting with vsphere 4 to focus on the needs of business critical application. Rdm virtual and physical compatibility modes vmware. A principled technologies test report 3 demonstrating vmotion capabilities with oracle rac on vmware vsphere figure 1. In essence its a modification of option 1 with rdms.
With storage vmotion, you can migrate a virtual machine and its disk files from one datastore to another while the virtual machine is running. Vmware vsphere vmotion, which simplifies common operations such as. Rather than creating a virtual disk vmdk on a lun, which is generally shared with other vms and virtual disks. Adding and sharing rdm disk to multiple vms in vmware step by step march 23, 2018 02. Vmware interview questions and answers vmware vmotion. Vmware virtualization rdm to vmdk migration house of. Vmware is well known for its vsphere vmware hypervisor. Vmware vmotion enables the live migration of running virtual machines from one physical server to another with zero downtime, continuous service availability, and complete transaction integrity. Vmware vmotion enables the live migration of running virtual machines from one physical. Hp3parpeermotiondatamigrationguide abstract thisguideprovidesinformationonusinghp3parpeermotiontomigratedatafromonehp3parstoreservstoragesyste.
The rdm uses a scsi serial number to identify the mapped device. He is the coauthor of the essential virtual san and vsan 6. The first step to adding a rdm to a virtual machine is to assign an unused lun to your esxi servers. Vmotion is a key enabling technology for creating the dynamic, automated, and self optimizing data center. Previously, this was only possible for virtual machines that used virtual disk. The remainder of the paper is focused on experiments conducted at the vmware performance engineering lab.
Rdms are used to meet use cases and could be considered a deviation from the normal. This is his personal blog related to mostly storage in virtualization and container orchestration. When you try to configure a local datastore as rdm in vmware esxi 6. For more info on capabilities and limitations pf physicalvirtual rdm, please refer vmware kb2009226. Storage vmotion of a virtualized sql server database.
Vmware raw device mapping rdm volume, detailed material. We were able to vmotion the host to another esx server and the gatekeepers still worked to allow solutions enabler config commands to be passed to the array. Note this is not a guide to using microsoft cluster service or failover clustering. Creating a raw device mapping rdm with vmware vsphere 5. For more information about rdm, see vsphere storage.
Virtual machines configured with the raw device mappingrdm for clustering features using vmotion vm cannot be connected to a cdrom or floppy drive that is using an iso or floppy image stored on a drive that is local to the host server. Raw device mapping rdm with vmware vsphere 5 youtube. My notes on raw device mapping rdm virtual reality. An rdm is a mapping file in a separate vmfs volume that acts as a proxy for a raw physical storage device. Vmware vsphere rdm or raw device mapping is the method to remove levels of abstraction from the storage presented to vsphere vms. The collected information should also include to which controller the rdm disk is connected and the rdms unit number.
Raw device mapping rdm is a method of disk virtualization in vmware that allows virtual machines to use a storage logical unit number lun device to be directly connected to a virtual machine in a storage area network san. Virtual mode specifies full virtualization of the mapped device. Folks, can we vmotion a vm with rdm luns in it from one node to another in a cluster on the fly. Does symmetrix dmx3 vs rdm physical mode vs vmware vmotion works. Vmware legacy identifier when sharing a rdm to multiple vms on different esxi hosts.
In this post, well learn the steps to configure storage vmotion on vmware vcenter server 6. Vmware vexpert lauren malhoit outlines the basics on how to convert a virtual machine disk format to a raw device mapping. Vmware is a california based company established in 1998 that develops virtualization platform for it infrastructure. Setup for failover clustering and microsoft cluster. Difference between rdm virtual and physical compatibility mode was one of the common questions people asked when we discuss rdm.
Vmware powercli script to get vms virtual and rdm disk. Local controllers not meeting the hardware requirements are often the reason of problems during the local datastore configuration configure a local datastore. Vcp 6 study note vm migration cold, vmotion, svmotion. Rdm is a mapping file in a vmfs volume that acts as a proxy for a raw physical device. Vmware crosshost storage vmotion recommendations 68. How to configure storage vmotion in vmware vcenter 6. I found this community created guide by kgottleib based on vmware kb3443266 on migratingconverting a physical. They had a sql server instance residing on a fusionio ssd card through a passthrough raw device map rdm on a vmware esxi 5. Vmware crosshost storage vmotion recommendations 66. Storage vmotion with rdms 18 aug 2010 filed in explanation. With storage vmotion, you can move virtual machines off of arrays for maintenance or to upgrade. Using microsoft cluster service in a virtual environment.
Adding shared rdms to multiple vms in vmware vsphere 5. You can use rdms in virtual compatibility or physical compatibility modes. Vmware esx server using raw device mapping this technical note is intended to help esx serv er administrators to understand how raw device mapping works and decide when its appropriate to use it. An excellent post that is very informative on vmware raw device mapping rdm volumes that explains what they are, the different between physical and virtual compatibility, when to use which and when not to use rdms at all.
You also have the flexibility to optimize disks for performance, or to transform disk types, which you can use to reclaim space. Storage vmotion with rdms scotts weblog the weblog of. If you are using the rdm in physical compatibility mode, you cannot use a snapshot with the disk. Also i would like to know if i put the esxi in maintenance mode, does all the vms including the ones with rdms connected get vmotioned to other nodes in the cluster automatically. Setup for failover clustering and microsoft cluster service covers esxi and vmware vcenter server. With the rdm, a virtual machine can access and use the storage device directly. Demonstrating vmotion capabilities with oracle rac on.
Well those older recommendations still apply today and to proof that vmware just published a new white paper that examine sql server performance on vsphere 6. For this task we had 6 x rhel6 vms which someone had asked us to attach the same rdm disk to in a non cluster aware scenario. It is stated in vsphere documentation that you can use vmotion with vms with rdm. Machine file system vmfs, virtual raw device mapping rdm, and physical raw device.
In the old posts, we have already learned the steps to configure iscsi storage on windows server 2012 r2 and also the steps to add shared storage to vmware esxi 6. Vmware powercli script to get vms virtual and rdm disk information i have been tasked to migrate several vms with rdm disks between storage arrays datastores. To configure a new datastore, you need to access vcenter server or local esxi. Moving an existing rdm from one virtual machine to another some steps are required to avoid data loss and to keep the disk. A fun customer of ours asked me today if you could convert an rdm directly into a vmdk. As part of that white paper they chose revisit the vmfs vs rdm topic and included testing of sql server performance on both vmfs and rdm disk. This video shows how to expand rdm disks on vmware infrastructure and windows vm. Intended audience this information is for system administrators who are familiar with vmware technology and microsoft cluster service. The data luns have been migratedcopied and all was left is the migration of the vm configuration files and rdm pointers. They wanted to migrate the sql server to the ssdbased area on their san so that the vm could benefit from vmware ha between. The reasons for doing this should purley be for functional and management reasons, not performance. The rdm file contains metadata used to manage and redirect disk accesses to the physical device. The goal of these tests is to gain a better understanding of the impact of application io characteristics on svmotion and the effect svmotion has on application performance. Vmware vsphere physical and virtual rdm bretts it blog.
This should allow, in case of scriptfailure, to restore the rdm mappings quite easily. The rdm contains metadata for managing and redirecting disk access to the physical device. Posted by zhaos2 in everything oracle at dell emc on nov 20, 20 11. There is a misunderstanding that rdms offer greater performance compared to vmdks on. Rdm is useful for supporting two typical types of applica tions.
Vmware cloud on aws is an integrated cloud offering jointly developed by aws and vmware delivering a highly scalable, secure and innovative service that allows organizations to seamlessly migrate and extend their onpremises vmware vspherebased environments to the aws cloud running on nextgeneration amazon elastic compute cloud amazon ec2. Best method for backing up vmware rdm disk is to install backup exec remote agent in the guest machine and take a backup of that vm as if its a physical machine by selecting the resources including the rdm drive from the under the vm server name in the selection list. I dont know about data devices, but i have tested a vm with gatekeepers provisioned from a dmx3 using rdm. It experts from five different fields developed vmware software. Creatingadding a raw device mapping rdm to a virtual. If the vml id is different which it will be if a different scsi id is used to present the rdm to different esxi hosts, then you will not be able to configure mscs. Vmware vmotion vmware vcenter server vmware 0343345600. Storage vmotion is required to move the vmdk or files of virtual from one storage to. A raw disk mapping rdm can be used to present a lun directly to a virtual machine from a san.
So, yes storage vmotion is supported for virtual rdms for both the rdm mapping file and the data disk i. Physical mode rdm pointer files can be relocated to the destination datastore, but cannot be converted. This direct connection can boost disk access performance in. Performance characterization of vmfs and rdm using a san esx server 3. Performance characteristics of vmfs and rdm vmware.
Because block devices and some directattach raid devices do not export serial numbers, they cannot be used with rdms. There iswas tons of space for the 50 gb, but not for the 3 tb that wasnt really moving, since its a. Vmware hypervisor enables virtualization for any architecture. New vmware position on vmotion of rdm luns with oracle database. Use vmotion to migrate virtual machines using raw luns. Scotts weblog the weblog of an it pro focusing on cloud computing, kubernetes, linux, containers, and networking.
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