Question on RDM and VMotion

[digitalex]

We currently use VMFS on all Storage Luns,(mainly cause they have multiple VM guests on a particular lun and it requires VMFS, 15 VMs per lun to be exact.)

did not think that RDM was supported with Vmotion/HA. Am I wrong on this? If RDM is supported for Vmotion then If I already have a datastore that was being used by a physical server can I lun mask this to all the esx servers and use it as an existing lun and all the data remain intact? I currently have a file server and database server both with D; volumes on the SAN. I could create 2 new VM guests and add disk to both using RDM?

[gary1012]

VMotion works with RDMs. Just tested one in virtual compatibility mode. I'm not sure if I'm following you on the other part...

[weinstein5]

It is supported - but the same rules apply both the RDM and raw LUN muct be seen by both originating and destination host -

[digitalex]

So it is supported. THen back to my second question. If I already have a lun on a physical windows box and I want to move it to a VM can I just use it as a existing storage unit and RDM so the data stays in tact without having to back it up by tape and restore it?

[lesnyh]

Добрый день. Спасибо за ваше письмо. Cейчас нахожусь на обучении и не имею доступа к почте. Буду 24 марта и обязательно отвечу на Ваше письмо. Технические вопросы можете адресовать, на vmware@softline.ru

[weinstein5]

The purpose of the RDM is to allow VMs to write to a raw LUNs accessable by the ESX - since the ESX host can access a windows fielsystem you will not be able to use an RDM to access that data

[lesnyh]

Добрый день.

Спасибо за Ваше письмо, к сожалению, я нахожусь в отпуске до 4 августа и мой доступ к почте ограничен. Все Ваши вопросы можно присылать на наш общий почтовый адрес vmware@softline.ru и мои коллеги Вам обязательно ответят.

С уважением, Марат Лесных.

[digitalex]

So a RDM is just a LUN without multiple vmdk's. Is the RDM formatted in a particular format that propritary to esx? So the windows NTFS partition is destroyed?

[mitchellm3 · Accepted solution]

A RDM is what it is...just a mapping for an individual VM to a LUN. This LUN can be formatted with any filesystem...hopefully one that your VM can read. So, to answer the second question.

1. Shut down your physical servers

2. Remap the two data luns to every ESX server in the farm.

3. With the fileserver VM shut down --> edit settings --> add disk --> RDM (I use virtual mode cause I don't need physical mode) --> select the LUN that was origionally attached to your fileserver.

4. Start up your VM

The VM will see the disk, since it was formatted with NTFS, it will be able to read the file system.

Do the same with the SQL VM.

*I'm assuming that you want the VMs C: drive on an existing VMFS3 datastore...you just want to attach the DATA drive from a physical server to your VM...more or less a cleaner P2V.

[weinstein5]

More specifically an RDM is actually a special VMDK file - that is why you need to specify a VMFS volume for its storage - that redirects the vmkernel to write to a LUN on the SAN -