To RDM or Not to RDM

[Brogan]

I am currently debating with myself 😉  weather or not to continue to use RDM on the file server which is a windows 2003 r2 but i want to upgrade to windows 2008 R2 so here is the conundrum. The windows guest os is vmfs partition on lun and the 2nd drive is a rdm physical ntfs partition on HP MSA 1500 lun. I need to move the data on rdm drive to another lun on HP MSA p2000 g2.

So would it be wise to move/copy the data to rdm lun configured physical/virtual mode or to vmfs lun. The lun size will not be greater than 1.2TB we have strict file server data storage controlls in place. what would be the fastest way to get the data across two luns; if i map 2x rdm luns to physical windows server the copy rate is about 30MB/s, tried in vm environment few weeks ago and the copy rate was terrible. 

[a_p_ · Accepted solution]

So would it be wise to move/copy the data to rdm lun configured physical/virtual mode or to vmfs lun

Although either of these option will work, I would prefer the virtual disk option, unless RDM is needed for e.g. MSCS clustering. Using a virtual disk reduces complexity and the number of LUNs and presentations you need to maintain. You will also be able to run image based backups in this case.

Regarding copying the data. Unless you manually aligned the Windows 2003 NTFS partition you are currently using, you may benefit from copying the data to an aligned partition (WIndows 2008 partitions aligned to 1MB). I often use Robocopy (included in Windows 2008) to migrate data. This command line utility is very powerful and allows you to even mirror the target with the source data. This way you can copy all the data to the target in advance and at the time you switch to the new server it will only synchronize deltas. Robocopy is also able to maintain NTFS and owner permissions if needed.

André

[Josh26]

André Pett wrote:

I often use Robocopy (included in Windows 2008) to migrate data.

I also highly recommend the Microsoft File Server Migration Toolkit. It has the added advantage of being able to present and remove shares during the process.

[TomHowarth]

as Andre says unless you are using MSCS's there is little or no need for a RDM volume,  the days where RDM's offered a perfromance increase are effectively gone now, this is even more the case with vSphere 5.

I too recommend RoboCopy for the data migration,

[Mouhamad]

Why don't you use internal SAN migration or cloning such as SAN copy and SAN Mirror?