Surprised by ESXi limited raid support

[steven6282]

ESXi seems like great software, but I'm really surprised by what seems to be a heavily limited raid support.

One of the most important things on any server is data protection.  Why would VMWare choose to allow such limited raid support in ESXi?

I configured a server a few months ago that had two seperate raid controllers on it, ESXi didn't support either of them, if I tried to configure a raid ESXi just looked at them as individual disks still.  So I said ok, it happens and just configured VMWare server on a Ubuntu 10.10 host and moved on.

Putting together another server now, different mainboard than I used previously, and has two raid controllers on it as well.  Neither of these seem to be supported as well.  So out of curiosity I installed ESXi on 3 of my desktop systems.  None of the 3 seem to have a supported raid controller.

That is just sad, out of 7 different raid controllers I've tested it on, it didn't support any of them.  Now I realize I could check the compataiblity list and simply get a raid controller card that is supported, but whats the point?  Does VMWare have a deal with some specific companies and only support their raid controllers or something?

I don't know.. the virtualization isn't really important to me on these servers atm.  It woudl have just been a convenience and nice to have a little faster hardware access in the vm boxes.  I'm just really disappointed in VMWare for not having better support for raid controllers in this.

[DSTAVERT]

ESXi requires a supported hardware RAID controller. Most embedded RAID devices do not have an offload processor for RAID calculations and require software running on the OS to handle it. If you want a supported hardware RAID controller have a look at the whitebox list at http://vm-help.com The Dell Perc 5 cards while no longer sold by Dell can be found at online retailers and auction sites. It is well supported and can be had quite inexpensively.

[Rumple]

One of the things you need to keep in perspective is the actual audience and usage pattern of ESX.

The audience is really targeted to business's who require stability, reliability AND performance.  No software based RAID controller can provide all of these things.  You can get reliability using software RAID to a certain extent, but not performance.

Usage - Remember that a software RAID controller with a single operating system on it running (say Windows SBS Server) is not gonig to be really hitting the disk I/O very hard and it will be a single read/write action at a time...

With Virtualization - you have multiple servers all reading/writing to the same disk at the same time and all requiring different types of I/O (some random, some sequential) and its all happening at the same time...

Software RAID controllers just cannot provide that business level performance and reliability therefore there is no reason for vmware to spend valuable resources builing in supprot for something that should NOT be used for business...

While we may want to use it for personal/training use on our desktop...thats what workstation or vmware server is for....

If you want to use ESX, you have to follow the rules...which means picking up a cheap server with a hardware controller on it...

[steven6282]

From a business perspective, I prefer software raid over hardware raid in applications where drive performance is not critical.

Software raid is much easier to recover if your raid controller fails.

I had a hardware raid fail a few years ago in an older server and could not find another hardware card with that raid controllers chipset in it.  So I lost the data and had to do a restore from backup onto a new array which was quite annoying.

Where as with a lot of motherboard raid controllers that use software raid, a linux distro can pick up the raid if need be.

Then of course there is the cost of hardware raid.  If it's not critical to the performance then why spend 600+ dollars on a good hardware raid card.  To me, vmware would stand to gain more business in the long run if they don't turn away the smaller businesses that use software raid and may later upgrade to hardware raid.

It can't be that hard to code in support for it, it's simply a matter at looking at what is being reported by the bios as there rather than only looking at what is being reported by the controllers.

[chriswahl]

I hear what you're saying, but software raid is pretty lame on performance, which would hurt your test of the product (especially the write performance). Even a cheap write-through RAID controller can perform poorly with just a few VMs.

The alternative is to buy a bunch of servers and run a physical work load. I'm sure that's a lot more expensive than a good RAID controller. :smileyhappy:

[mcowger]

Its also wroth noting that the vast majority of businesses using ESX/ESXi are doing it with shared storage - e.g. a storage array of some sort.  The list of supported arrays is MUCH MUCH MUCH longer :smileyhappy:.  Vmware focuses on the arrays because thats what most customers want and use.