VMware ESXi – Cannot add VMFS datastore

To give some greater context, see my previous post.

When I was initially planning on how to setup these drives, I configured them with the HP P410 RAID utility as a RAID-0 array. I made the decision to not live such a risky lifestyle and blow away the array and configure it for RAID-1. I want to build a solid homelab that will assist me in aspects of systems administration so I didn’t want to risk everything by running the wrong array.

Anyways, when I booted into VMware, I was unable to add the VMFS datastore after setting it to RAID-1.

I received the following error:

“Failed to create VMFS datastore – Cannot change the host configuration”

As seen by VMware ESXi

I did a bit of searching around and tried to re-scan the datastore and get vmwre to detect it but nothing was working. I soon came across the following VMware communities post here, user Cookies04 was on onto something.

The user identified a very familiar scenario to mine.

From what I have seen and found this error comes from having disks that were part of different arrays and contain some data on them.”

That’s the exact thing that happened to me. RAID-0, some VMware data, then RAID-1.

I proceeded to follow the three easy steps and my issue was solved.

To correct the reported problem

I didn’t really have to post all of this but I wanted to in case somebody were to come across my page and had the same issue.

The interwebz if filled with many many solutions for issues. I’m just adding what’s worked for me.


HP Ml150 G6 – My first datastore

I don’t spend the amount of time on my home server as I’d like to. After a long day of sitting at my desk at work, dealing with production servers and everything super sensitive, I try to unwind a bit and work at a slow pace. My slow pace this week is my esx datastore.

I’ve spent the past couple of days thinking about how I want to setup the datastore that will contain my virtual machines. Initially I had the HP P410 RAID controller connected to two, WD Green drives in a RAID-o array. I was satisfied with that at first because the drives will run at SATA 2 speeds and hopefully RAID-0 will improve the performance ever so slightly.

Then I got thinking, my goal is to setup a ‘corporate’ environment at home. Multiple domain controllers, WSUS, Sophos Firewall, play with SNMP and PRTG monitoring but that made me realize that I don’t want to build a large environment that will go to waste if one drive was to fail. My ultimate goal is to move onto SSDs and use a more complex raid (RAID 6 or 10) for this server, but that’s down the line when I free up funds and more resources.

Last night, I decided to delete the RAID-0 array, pull out the WD Green drives and install two new-to-me 1TB SAS drives and proper cabling (Mini SAS SFF-8087 to SFF-8482+15P). I briefly talked about the cabling in this previous post.

I purchased a few SAS drives from ebay, not knowing exactly which one would be compatible with the HP P410 raid controller. Most of what I can find on the internet, points to the HP P410 controller not being picky with the brand of drives.

Initially I installed a two Seagate 1TB SAS ST1000NM0045 drives but the RAID utility would not want to see the drives. Thinking it’s the cable, I replaced it with a spare but the outcome was still the same. I did a bit of searching around and found a discussion on serverfault.com, regarding HP Proliant not recognizing EMC SAS drives. One user points out that some drives can be formatted in 520-byte sectors vs 512-byte sectors that you would normally get on normal PC/server class drives.

I haven’t tested that theory but I will. With that said, I decided to install two other drives, which surprisingly worked right away.

The drives that are functioning fine with the HP P410 raid controller are:

  • Dell Enterprise Plus MK1001TRKB
  • Seagate Constellation ES.3 ST1000NM0023

Now that I have two drive’s in a RAID-1 array, I loaded into VMware ESXi and proceeded to add a the new VMFS datastore. Adding the datastore gave me some issues, which I’ve documented here.

I have in my possession two SAMSUNG Data Center Series SV843 2.5″ 960GB drives that I purchased about 2 years ago from newegg for a fantastic price. I’ve toyed with using them in this build, but the SSD drives would only work at SATA 2 speeds. Maybe I’ll use them to house my personal data, but I should purchase a few more to do RAID-6 or RAID 1+0.

Regardless of my direction, I am still working out the kinks in my homelab environment.

Ideally, I’d like to find a cheap or reasonably priced NAS that has iSCSI ports. I then would be able create two datastores on the NAS, one for extended VM storage if required and the other for user data.

Thanks for reading.