Regardless of the fact that I am a fan of engineering my own products, such as the OpenSolaris iSCSI custom SAN, I have always been attracted to the Data Robotics product line, the Drobo. I am not much of a Apple fan either, however, similar to Apple, the Drobo product is well designed and marketed. For those that are wondering how well the DroboPro works with VMware, I am right here with you, wondering the same thing. So, let’s get started…
Getting Your DroboPro Online!
Obviously you should follow the guides provided to you by Data Robotics for initially setting up your DroboPro. If you seem to be blinded by consumer user guides, the initial seup is easy: (a) insert drives; (b) power on; (c) install Drobo Dashboard; and (d) connect via USB to a workstation. Yes – we start with configuring the device through USB…
Configuring Volumes on DroboPro
Now that your DroboPro is accessible through the Drobo Dashboard, we will start with configuring the volumes. For those that are not familar with iSCSI, these volumes will become iSCSI LUNs from the VMware host perspective. Do not worry about the fact that you have to create the volumes in NTFS as that filesystem will be destroyed when we begin to utilize the volumes for VMware ESX(i). Also worthy of mentioning, the drive letter that DroboPro is assigning to each volume has no value once VMware ESX(i) takes ownership of the volume.
As you may be aware, VMware does not understand LUNs larger than 2 TB, so if your DroboPro has a large disk capacity, you will need to create multiple 2TB volumes. My DroboPro has 8x 1TB hard drives installed. This is accomplished in the Drobo Dashboard software application as shown in the screenshot below:
Configuring iSCSI on DroboPro
The next step is to configure the DroboPro with an IP address for iSCSI connectivity. Not that anyone would want to route iSCSI traffic, however, you will notice that the iSCSI IP address designation does not allow you to configure a gateway IP address. You must use the DroboPro in the same subnet/VLAN as the ESX(i) hosts. This configuration change will require a reboot.
Connecting ESX(i) and DroboPro
If you have an existing SAN, you will want to follow the same configuration, connecting your DroboPro into the Storage Area Network (SAN). Separate networks requires additional VMware configuration, such as another Virtual Switch and VMKernel. If you are a small shop and have the DroboPro on the same network as your production environment, then the only modification will be adding the iSCSI IP address to the VMware iSCSI Software Initiator and performing a Rescan on the adapter.
Note: The DroboPro seems to have a difficult time being an iSCSI target while also connected via the USB port. Now would be a good time to disconnect the DroboPro from the USB cable and visa versa.
On the Configuration tab of your ESX(i) host, choose Storage Adapters and click on the Properties… link within the iSCSI Software Adapter (vmhba32). First, within the iSCSI Initator (vmhba32) window, General tab, ensure that the Software Initiator Properties states Status Enabled. Second, on the Dynamic Discovery tab, add a new iSCSI server and enter the same IP address as you configured on the DroboPro.
In addition, ENSURE that you use port 3261.
The standard iSCSI port 3260 may work; I ran into connection issues when I tried to add another ESX host in the mix. According to DroboPro VMware best practices, the DroboPro can handles up to 4 ESX(i) hosts and they recommend port 3261. Perform a rescan of the HBAs and you should see the LUNs appear, matching the volumes you created earlier.
Adding Storage on ESX(i)
If you have ever worked with iSCSI and VMware, and hopefully you have if you are using VMware in a production environment, then you understand the next step. You will need to create the VMFS volumes from the iSCSI LUNs. If you are confused with iSCSI LUNs, think of an iSCSI LUN as a SCSI LUN, for even though it is software based in our environment, it is utilized as though it is a hardware device or array.
At this point, VMware will destroy the current file system (NTFS) that we created when we create the volumes earlier.
Now you can use the storage to offload test/production VMs, create new VMs, et cetera.
I did some simple performance testing on the DroboPro using two methods, one with Windows and VMware file copies and the other using iometer.
|Microsoft iSCSI Software Initiator
(Windows file copy)
|2GB file copy||42MB/sec write||38MB/sec read|
|VMware Software Initiator
(using Datastore browser upload)
|2GB file copy||7MB/sec write||(I/O error) read|
|VMware Software Initiator
(using VM Windows share of iSCSI LUN)
|2GB file copy||<5MB/sec write||<5MB/sec read|
|iometer||32KB 100% Sequential||14 MB/sec write||30 MB/sec read|
|iometer||1MB 100% Sequential||19 MB/sec write||40 MB/sec read|
|iometer||8MB 100% Sequential||52 MB/sec write||61 MB/sec read|
Before we get too much into the performance I gathered, I want to state two things: (a) my lab environment has fairly old Dell servers and workstations, however, even iometer can produce 57MB/sec on the IDE workstation hard drive; and (b) the VMware results are too low to believe, especially considering that the DroboPro is now VMware certified. To be honest, I am not even certain I set up the test appropriately in iometer. My goal with the configuration was to simulate a file copy with 100% sequential write or read. Click here to download the iometer configuration I used for this test.
Overall, I am fairly pleased with the performance using the Microsoft iSCSI software. As with VMware, the performance is lacking. I will be doing a more thorough performance test with VMware in the near future.
As a final note, be sure to review the Data Robotics document on DroboPro VMware best practices.