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.
Performance
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.
-Aaron Gilbert
IT is not just a job but also a passion. Everything I have accomplished, both personally and professionally, has been generally entertaining, bordering on fun. Some of my projects, such as working with SharePoint Services workflow actions in Visual Studio or building a custom iSCSI SAN using the OpenSolaris, ZFS and COMSTAR, has been quite rewarding. You may think nerd...I think developing a new trend!
For those that are wondering, it is my opinion that the DroboPro is not quite ready for a production VMware environment. I saw performance anywhere from 5MB/sec to 55MB/sec with no change in configuration while cloning a VM from an EqualLogic to the DroboPro. Being that the DroboPro is VMware certified, I had high hopes for an inexpensive and solid iSCSI target when I purchased the DroboPro. For those that are going to use the DroboPro with the Microsoft iSCSI Software Initiator I was fairly impressed with the product, both performance and configuration ease.
In case someone at Data Robotics reads this post, these are my thoughts in regards to enhancing the DroboPro:
1. Make the option to create a volume without a filesystem type – although its not really an issue, formatting it NTFS gets confusing when the intent is to add the LUN to VMware and format with VMFS
2. Create a web interface for configuring the DroboPro for those that intend to use the device as an iSCSI target. Keep the Drobo Dashboard for USB/Firewire use.
3. Enable security features such as ACL, CHAP.
4. Provide some method of knowing what the DroboPro is currently doing. I realize that the engineers want the back-end of the DroboPro to be lock out, however, a simple status would be nice as we wait 15 minutes for the DroboPro to figure out what it is doing.
I am actually disappointed that I have to return the DroboPro – I would like to spend some more time troubleshooting, however, work duties make the “calls” and I need a functioning/simple iSCSI target yesterday. For those that are wondering, I re-purposed an older Dell server, some external eSATA storage, and installed the opensource OpenFiler product. Performance is pretty good with OpenFiler. If you want more robust SAN capabilities, try OpenSolaris and COMSTAR – just keep in mind that OpenSolaris is picky on the hardware and performance is DIRECTLY affected by the hardware you choose.
That is it for now…
-Aaron
Doing some testing with:
Dell R610
Drobo Elite
Dell Powerconnect 2724
- jumbo frames enabled start to end (vswitch, vmnic, vmkernel), on the switch, and on the Drobo Elite
Doing an upload/download from a Windows 7 workstation to the Datastore on the Drobo yields about 20MB/sec throughput (as reported by Windows). A similar upload/download to a normal file server jumps upwards of 80MB/sec.
I thought performance would be a little better than that…
I can 2nd your results. I’m just finishing my testing of a DroboPro and am VERY dissapointed by the VMware performance. Even connected directly to the server I was only getting at most 6MB/sec. This is unacceptable for a device that costs this much. It’s interesting that a device can be VMware Certified and “Supported” but not actually work.
In our environment, the DroboPro was going to be used as storage for test/DR virtual machines, temporary storage and for the occasional production virtual machine. The performance was so poor that VMware would sometimes fail during a machine migration from one datastore to another. The replacement for the DroboPro was to use OpenFiler on some older Dell equipment. Currently we use OpenFiler as an iSCSI target on a PowerEdge 2650 and PowerEdge 2850, both with eSATA attached storage. Surprisingly, OpenFiler on these older systems is quite stable, 60+ days up time on one – to top it off, OpenFiler’s iSCSI (which is the IET project) has compatibility with ESX 3.5 U3, which the DroboPro couldn’t do.