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Dell PE 2950, PERC 6/i Controller. - ESXi 5.1 installed/Boot from USB drive. 2 x 1 TB SAS drives in RAID 1 - Datastore1.1x 2TB SATA drive set as RAID 0.

We wish to host all our VMs from Datastore1 and add the 2 TB SATA as a Raw Disk mapping to one of the VMs. This option is at the moment greyed out. We wish to use this as a simple storage no other purpose.

My questions 1. Does PERC 6/i support RDM, if not is there a work around to add the local SATA as a RDM. 2. I was only able to see our 2 TB drive in Vsphere after configuring it as RAID0, our intention is to make this as a NON RAID drive. Does removing it from the RAID help in anyway? 3. Is it compulsory to confugre all onboard drives into the RAID? can I see my 2 TB drive in ESXi without adding it into RAID.

P.S - I understand one workaround is to create a VM on top of this 2 TB. I am worried about several other factors and wish to keep this as a last option

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migrated from Apr 25 '13 at 20:45

This question came from our site for computer enthusiasts and power users.

  1. VMware's compatibility guide for ESX 5.1 list the PERC 6/i and the PE2950 as being supported hardware. The controller card itself doesn't have its own support matrix, as that is governed by the support matrix of the server it shipped in, and the OS you're running.
  2. A single disk RAID0 is not really configuring a RAID on the disk. This is just a minor annoyance you'll have to put up with since the PERC card is acting as your internal SAS/SATA controller.
  3. If you're using the PERC 6/i as your SAS/SATA controller, then I believe all internal disks would have to be presented to the OS through it (as part of a multiple or single disk RAID). If you don't even want to have a single disk RAID (even though no striping of data is actually happening), you would have to disable the PERC card entirely in the BIOS and let the motherboard's integrated Intel SATA controller handle things. This wouldn't go over very well for the existing RAID 1 though (i.e. this could set you up to destroy the data on the RAID 1)

As for the actual problem you were having w/ the lack of ability to RAW device map the single disk RAID 0... You might still be running into the 2TB limitation on RAW mappings if the disk is slightly too large; it can't be 2TB exactly, as the max is 2TB minus 512 bytes. I doubt this is the case since a "2TB" disk usually equates to about 1.82 TiB of usable space, but you may consider creating a slightly smaller 1.95TB RAID0 on that drive (instead of the full capacity available).

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Yes you are right. The actual size shows it as around 1.8 TB.

I finally managed to add it as a RDM using the below help (With a few minor changes)

But after doing so I now realise that moving raw data/files to this volume from a local USB/system is a very daunting task in itself. As my requirement was to use this as a raw storage, I have around 1.5 TB of data I want to load into this disk and then use it across the VMs. I spent whole night comparing the data copy speeds from outside into these disks and below are my observations.

Outside to the disk, when added as a ESXi datastore (not as RDM to VM) - 5 mins for 10GB. Outside to the disk, when added as a RDM to a VM - 25 mins for 10GB.

I wonder if there is a way to add an existing NTFS volume as a datastore without loosing data or needing to format it with VMFS?

I understand all these queries of mine are probably not common, hence have stared considering a NAS. But just want to see if there is anyone who has any tips/tricks to get this done.

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