multiple datastores on same disks

[dirtdevil01]

This is so strange. I can't create multiple datastores on the same disk. I have a 2TB disk plugged into my server (motherboard) and after I create my first datastore (100GB), when I go back to create another one, that disk is no longer an option for me to create a new datastore from. When I delete the datastore, the disk shows up as an option to create a new datastore from. Wtf???

[a_p_]

Only one datastore per disk/LUN is supported. If you want do create other datastores anyway you have do do this via CLI (fdisk, vmkfstools).

André

[dirtdevil01]

I find that hard to belive. theres no way vmware would rig the vic to only allow one datastore per disk. Is there an official pdf doc that states this?

[a_p_ · Accepted solution]

from http://pubs.vmware.com/vsphere-esx-4-1/wwhelp/wwhimpl/js/html/wwhelp.htm#href=fc_san_config/c_making...

One LUN must contain only one VMFS datastore.

I guess the reason for this is SCSI reservation. Even though this has been reduced significantly in 4.x it's still needed for some operations. Each SCSI reservation - even though this is only needed for an operation on one datastore - locks the whole disk and could therefore cause issues on other datastores on the same disk.

André

[dirtdevil01]

Our company is moving to esxi for virtualization but the problem is we have more then one admin and certain admins shouldn't have access to other admins vms BUT all admins should be able to freely create vmdks. Since they are admins they should be able to freely create vms as they need fit. The problem is from what I've seen in vcenter, vcenter can only support datastore level access and not folder access within a datastore. So if I have one big 4TB raid array and I can only put 1 datastore on it then it would have to be a 4TB datastore and only 1 admin could be able to access it which leaves the other admins out in the cold.

[a_p_]

Most modern RAID controllers have the ability to split the RAID volume into logical volumes.

So let's assume you have four 2TB disks. Then you could create a RAID 10 and configure the RAID controller to present e.g. one 20GB logical volume for the hypervisor (this size would allow you to have a small datastore on the OS volume, which you can use to provide e.g. ISO files) and multiple larger logical volumes (600GB is a good average) for the virtual machines.

Since you mentioned the 2 TB disk, I assume you are working with SATA disks. In this case I'd recommend to create a RAID 10 rather than RAID 5 to get better performance. Also make absolutely sure the RAID controller has battery buffered write cache to support write-back operation.

André