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  • 1.  Datastore NFS or iSCSI

    Posted Mar 13, 2019 02:20 PM


    I am installing my new VMware 6.7 infrastructure on my storage but I have the choice between NFS or iSCSI.

    I know this question has already asked but when I see older discussion on it, it is on different storage.

    But me I can choice NFS or iSCSI on the same storage.


  • 2.  RE: Datastore NFS or iSCSI

    Posted Mar 13, 2019 02:58 PM

    I work as a freelancer and offer VMware recovery support.
    All my customers use FibreChannel or iSCSI.
    In other words - in my experience NFS is radically more reliable.
    That applies especially to small vSphere-setups.

  • 3.  RE: Datastore NFS or iSCSI

    Posted Mar 13, 2019 03:51 PM

    Thanks for your reply.

    But are you sure when you say "NFS is radically more reliable" if all your customers use Fibre Channel or iSCSI?

    So if I understand for small infrastructure is better to use NFS and for big infrastructure it is better to use iSCSI ?

    Is it correct?


  • 4.  RE: Datastore NFS or iSCSI

    Posted Mar 13, 2019 04:48 PM

    It is not about NFS vs iSCSI - it is about VMFS vs NFS.
    VMFS is quite fragile if you use Thin provisioned VMDKs. A single powerfailure can render a VMFS-volume unrecoverable.
    That almost never ever happens with NFS.
    To use VMFS safely you need to think big - as big as VMware suggests.
    So instead of a single ESXi host with local disks you use 2 or 3 or even more hosts and implement regular automatic backups via Veeam @CO and implement regular replication to another locatition.
    If you do not have the budget to implement a vSphere environment with that features you are better off if you either consequently avoid all Thin-provisioning or use a NFS-storage instead.
    Small environments often do not have the money to implement all features that work around the short-comings of the VMFS-filesystem.
    If something goes wrong those environments need to recover or repair their corrupted VMFS - a large environment that thought as BIG as VMware suggests does not need to recover - they can instead just hit a button and switch to a replica ....
    So my suggestion is to use whatever performs best - if you think big enough - or use NFS if your budget is limited.
    Most dangerous setup: a single host with local RAID controller using Raid 5 and lots of Thin-provisioning..

  • 5.  RE: Datastore NFS or iSCSI

    Posted Mar 13, 2019 07:36 PM

    It depends, I have used both.  Remember that presenting storage via NFS is different from presenting iSCSI.  With iSCSI, the VMware hosts see block devices which will be formatted with the VMFS (Virtual Machine File System).  NFS presents a file system to be used for storage.

    A lot of your choice depends on the hardware/software you are running. For example, if you use the NFS server role on Windows Server to present storage - it's going to be a bad experience. Microsoft's implementation of NFS is not very good.  If you use a Synology device and present iSCSI to vSphere, you'll hit severe performance issues!  The above are just known issues with those vendors.  Generally if you buy a dedicated server (Dell, HP, Supermicro) or build your own and use quality network cards (Intel, etc.) you will see similar performance regardless of which protocol you use.

    One thing to mention between iSCSI and NFS is, with iSCSI you can utilize multipathing and load balancing to provide redundancy and reliability; I believe vSphere still connects via NFS v3 which means you won't have those options.

    I personally prefer iSCSI, I would rather let vSphere manage the file system

  • 6.  RE: Datastore NFS or iSCSI

    Posted Mar 14, 2019 01:28 PM

    This paper is a couple of years old but still worth reading, although some details have change:

    Personally, I would probably go for NFS, much easier to configure etc. Unless you need a feature like UNMAP, then you would need to go iSCSI. That is probably the biggest difference right now.

  • 7.  RE: Datastore NFS or iSCSI

    Posted Mar 14, 2019 01:29 PM

    I'll have to take a look, thanks!

  • 8.  RE: Datastore NFS or iSCSI

    Posted Mar 15, 2019 04:13 PM

    Just a quick note: ESXi 6.0+ does support NFS 4.1:

    NFS Protocols and ESXi

  • 9.  RE: Datastore NFS or iSCSI

    Posted Mar 14, 2019 02:20 PM

    Thanks very much for your comments.

    I think I will try to create a datastore with NFS and another with iSCSI. I think I can mix different technology.

    I don't know if I can find a tools to measure performance. Do you know ?

    Another question because when I want to create a new volume on my NAS I must choice a file system.

    I can use ext3 or ext4 or btrfs.

    If I create with btrfs I cannot find the volume on my esx after a rescan? Do you know why ?

    Maybe BTRFS is not the best choice...but I thought it to make snapshot on my volume to restore

    So actually I have create one datastore with EXT4. What do you think ?

    Thanks very much

  • 10.  RE: Datastore NFS or iSCSI

    Posted Mar 14, 2019 03:10 PM

    > If I create with btrfs I cannot find the volume on my esx after a rescan? Do you know why ?
    Please explain !
    If you use NFS the NFS-server handles the filesystem and the ESXi should not notice any difference between ext or btrfs.
    ESXi itself can not read ext3, ext4, btrfs at all.