Do I still need RAID 10 when using vSAN?

Hey, I am new to VMware as I am working to modernize my hosting. We have a few boxes and are looking to convert from our handful of isolated ESXi hosts (v6.7) to a more dynamic vCenter managed cluster as it grows.

One of my devs is helping architect the phased apporach and told me that the new hardware we will move to shouldn’t require RAID 10 as it vSAN would manage that and be just as good. I am a bit afraid to have to go to our customers and tell them we are using anything other than RAID 10.

How recommended is it to use just vSAN OR vSAN with RAID 10? I was being told that vSAN manages the RAID 0 and the RAID 1 parts of it so I shouldnt worry. Given that its my job to worry, I am am still worrying about how this will handle down events and redundency.

Also, I did see people talking about this online, but all the questions around it are 5 years old and I want to get a fresh perspective.

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  1. The **only** time you should ever pass through a RAID volume to be used as a vSAN disk is when you’re using one of a handful of storage controllers where the supported configuration requires configuring each individual drive as a RAID 0 volume (and I’d encourage you to avoid these controllers altogether in favor of a true HBA instead). In the vast majority of cases, vSAN should be given direct access to the disks via HBA (or supported RAID controller in ‘HBA Mode’), or via PCIe bus.

    Anything else is unsupported, and will almost certainly run into some kind of a failure or bizarre issue at some point in time. Don’t do it!

    >I am a bit afraid to have to go to our customers and tell them we are using anything other than RAID 10.

    This is just a matter of embracing the paradigm shift away from traditional block storage to software-defined object storage.

  2. Elver is the man when it comes to teaching vSAN. Check out how vSAN protects data using Failures to Tolerate or FTT.

    If you have more than 4 hosts and the appropriate vSAN licensing (advanced or better AND an all flash array on 10gb) you can leverage erasure coding.

    If you want to go fast(er), you need to know about Disk Striping.

    More importantly, this conversation starts and dies with the vSAN Hardware Compatibility List. If your hardware isn’t signed off, you’re probably going to have a bad time.

  3. The same question i asked Elver in one of my trainings about whether we require RAID or not.

    He said “we should not compare traditional infrastructure to VSan” long story short raid not required.

  4. I would highly recommend doing some more research before jumping into vSAN. I currently manage a couple of vSAN environments. However, we researched, planned, and tested for months before implementing it into our VDI environments.

    I would check out the following

    vSAN hands on labs

    YouTube resources




    VMware Storage Hub (Amazing Resource)


    vSAN deep dive book (This by far helped with our deployment)


  5. > new hardware we will move to shouldn’t require RAID 10 as it vSAN would manage that and be just as good

    Correct, for SAS/SATA SSDs you would use a regular pass through HBA. What server vendor are you working with? If it’s Dell it would be an HBA 330+ as an example. If you need help reviewing the BOM and design the vSAN Sales Engineers can help. DM me your info and I”ll connect you.

    >am a bit afraid to have to go to our customers and tell them we are using anything other than RAID 10.

    Lets turn this around. I’d be afraid to go to my customers and tell them my data is only on a single server with a single RAID group, and lacks even basic VMware HA protection to recover from a server failure. Shared storage is critical to maintaining availability, and RAID controllers checksum/scrubbing system are frankly not that robust compared to vSAN. Due to consolidation in the industry and multiple rapid M&A and passing of IP and assets, I frankly question the quality of their firmware engineering for anything more than pass through…

    > vSAN with RAID 10

    vSAN with objects over 255GB or with a stripe size set higher than 1, and using FTT=1 RAID 1 will effectively be a distributed virtual RAID 10. (Striped and mirrored) across the cluster.


    > Given that its my job to worry

    Your job is to mitigating risk, while delivering business agility and controlling costs. Everything else for an architect is fluff. It’s worth noting a lot of other people with a lot to worry about have adopted vSAN.

    1. My hospitals (Both adult, and pediatric). have PB+ deployments. The last storage failure they had (Prior to using vSAN, when they were using a legacy storage array that only does RAID 10 oddly enough) resulted in a 6 hour outage that prevented orders from going in, and charts from being visible. Thankfully vSAN stepped in to replace it.
    2. My banks (Two of the biggest in America) One has over 100PB of vSAN deployed last time I checked.
    3. My Payroll company (ADP) who makes sure I get paid.
    4. My brokerage/retirement account company.
    5. [Various people who need to carry around missiles and nuclear reactors](https://www.theregister.co.uk/2017/03/21/vsan_adding_filesystem/)….

    While you should certainly do your homework, I’m in a position where my life and my money depend on vSAN so I don’t really have a choice.

    > I am am still worrying about how this will handle down events and redundency.

    vSAN detects the failures, and (assuming properly designed with spare capacity) automatically re-mirrors the data. vSAN is smart, it knows the difference between a device being physically pulled, vs a hard PDL (physical Device Loss) failure. It adapts. It’s smarter than you (and a hell of a lot smarter than a basic RAID controller). It applies at host generating the storage IO a CRC32 checksum. This checksum is verified as the data is destaged on the remote hosts. It is verified again on all reads. This detects and helps scrub and isolate corruption.

  6. You cannot do any level of RAID on each individual host. In fact – your RAID controller in the host needs to support a “Pass-Through” mode. vSAN handles all of the disk level RAID controls.

  7. I currently architect, deploy, and maintain hybrid, all flash, and stretch cluster vsan deployments for current employer

    you do not use any raid or raid controllers as pass thru, verify with vmware vsan hardware compatibility list for hba controllers since they are build for hci…anyone suggesting otherwise is incorrect

  8. In a scenario where any of your server can fit on one host in one location I don’t see any benefit in VSAN. The price is way too much.
    There are better more cost effective HA solutions available. I recommend going full NVME and working with vMotion all the datatiering cost more in software licensing than the fastes hardware. Load balancers and VEEAM replicas are good HA solutions.

  9. After you have read a few vSAN guides and done **EXTENSIVE** testing and PoC you can go to your customers and say that you have Software Defined Storage and explain to them how it works compared to Raid…

    I agree with other comments about implementation of vSAN – Don’t do that if you don’t have dedicated storage people, as the same says, you are are implementing a **SAN** on your ESXI boxes and that menas complexity and, god forbid if something breaks spending more time on recovery as there are less guys knowing this tech.

    I think you should ask yourself: WHY first

  10. Short simple answer – no.

    Long answer:

    You have to look at RAID differently in a vSAN cluster. My company has a bunch of them out there of assorted sized from 2 hosts to I think 6 hosts.

    On each host, the drives are not RAIDed. That is handled by vSAN. If you go all SSD (recommended), configure the host level vSAN as RAID5 or 6.

    Then you RAID the cluster. Two hosts is RAID 1. More than two hosts should be RAID5.

  11. vSAN uses local disks in each host and stitches them all together to create vSAN volumes.
    Given that it uses local disks, you will not require a separate SAN. Some RAID controllers can present the disks natively to ESXi or like in our case, you may need to create a RAID 0 volume using each individual disk so that vSAN can see it.

    This is basic information, but a quick Google will yeild more information.

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