Physical drive mapping in ESXI

tom01 · 21 Mar 2020 at 16:57

Hi guys,

I have an ESXI server with two physical drives installed. The first one holds all my VM's and associated datastores for those. I want to use the second drive for additional data storage as and when required.

Annoyingly I had this working previously when I set it up with the VMware thick client but I can't work out how to do it on the v6.x web client.

Do I need to create a datastore on the 2nd HDD? It will used be used only for raw storage and I'll share it out over the network for other VM's to be able to read/write to when required, but primarily it will be one VM requiring usage.

Any advice would be greatly appreciated, I'm running ESXi v6.7

tom01 · 21 Mar 2020 at 17:02

Ok I think what I am after is Raw device mapping, can anyone give any pointers?

tom01 · 23 Mar 2020 at 16:41

Thanks

I managed to complete the RDM action, however a new problem I am experiencing is that the storage drive is only presenting to Windows as a 2TB drive (1.5 TB usage storage), despite being a 6TB HDD. I'm still researching this at the moment, there appears to be a previously known issue with older versions of ESXI where there was a 2TB limitation on VMDK files, however this should have been resolved in later versions.

I'm on a version (ESXI 6.7 with a VMFS6 datastore) which is reputedly not affected by this issue but for reasons I can't work out at the moment the issue remains. It's driving me insane!

tom01 · 23 Mar 2020 at 19:41

Throrik said:
RDMs are also a bit old-school and not really recommended anymore unless you have very specific requirements. I work in a place which still heavily utilises them and they're a bloody nightmare.

Edit - with your reply:

VMFS5 supports greater than 2 TB disk size for RDMs in physical compatibility mode only. These restrictions apply:

https://kb.vmware.com/s/article/2009226

Thanks for your reply and the link, can I ask what is the best way to achieve my goal then if RDM is considered an old approach? I have installed a secondary HDD which I want to present to a VM as a logical drive so that I can store large amounts of data to it and make it accessible to other network hosts. However in an ideal world I want the data stored on it raw so that if I were to remove it I could simply re-insert and the data is there as was. I thought RDM Was the best way to achieve this?

The only other route that I can think of is to create a datastore on the secondary HDD, but that isn't quite what I am after if I have understood correctly.

Last option I guess would be to use a NAS, however I ideally I'm not ready to do that just yet, that's long term.