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Disabling the VMFS-2 module! Exploring the next generation of ESX

Duncan Epping · Mar 13, 2009 ·

When I started out with ESX 3.0.x the first thing I wanted to do was disable the VMFS-2 driver. There’s no need for it when you’re not accessing VMFS-2 volumes and removing it can lead to performance gains or at least a faster rescan of your storage. Removing it, according to to this section of the VMware website, was supposed to be really easy:

vmkload_mod -u vmfs2

Unfortunately, this just unloads the module and every time the server gets rebooted the module is loaded again. Same goes for the esxcfg-module command, it unloaded it but after a reboot the module was loaded again. You could add the command to /etc/rc.local of course. This would unload the module every time the server booted. I’m not a big fan of manually changing files like this, and luckily as of the next generation of ESX(vSphere) this doesn’t seem to be necessary anymore:

esxcfg-module -d
-d|--disable - Disable a given module,
indicating it should not be loaded on boot.

The funny thing is when I run the “esxcfg-module -l” command it still lists the module as loaded. If I run the “esxcfg-module -q”, which only queries the enabled modules, it’s not listed. After a closer investigation I noticed that the following line changed in “/etc/vmware/esx.conf”:

/vmkernel/module/vmfs2/enabled = "false"

I did a cross-check, it’s most definitely not loaded. Cool, remember this one “esxcfg-module -d”. It will come in handy some day.

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Server ESX, esxi, Howto, vSphere

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Comments

  1. daniel says

    13 March, 2009 at 17:38

    is it safe to unload vmfs3 too if you’re an NFS-only shop?

  2. Christian says

    13 March, 2009 at 18:28

    I presume so, since ESX isn’t using any VMFS functionality (besides for local storage) on NFS.

  3. Scott Lowe says

    13 March, 2009 at 22:31

    I don’t know definitively, but I’d probably recommend against unloading the VMFS-3 module, especially in the next-generation stuff.

  4. BBCode-EnterpriseExpertProgrammer says

    17 March, 2009 at 10:51

    So is it safe to assume that you can also unload and disable the migration and nfsclient modules if you don’t use NFS Datasores and VMotion or HA features?!

  5. Duncan Epping says

    17 March, 2009 at 10:57

    I wouldn’t unload migration modules etc. I would unload VMFS-2 and/or NFS if you’re not using it. Be sure to document your changes!

  6. mellerbeck says

    10 November, 2009 at 19:28

    You mention that this changes for vsphere but I couldn’t discern if the command you used:

    esxcfg-module -d
    -d|–disable – Disable a given module,
    indicating it should not be loaded on boot.

    Is the vsphere specific command for unloading vmfs-2?

    Thanks,

    Michael

  7. Mats says

    8 December, 2009 at 16:04

    So where would people recommend editing this info in?

    i know the command used to be: vmkload_mod -u vmfs2
    Are you saying the new command is: esxcfg-module -d vmfs2

    Thanks

  8. Duncan says

    8 December, 2009 at 19:30

    Yes. it’s just a command, run it on the Service Console.

  9. ysemenihin says

    12 December, 2009 at 19:59

    Hi all, i try this but when i reboot host and check (using esxcfg-modules -l) i see that vmfs2 module is loded, i try unload module using vmkload_mod -u vmfs2 an then update bootloader using esxcfg-boot -b but stil no luck after this manupulation i have edit /etc/rc.local file to unload driver after system startup

  10. Tom says

    25 May, 2010 at 18:10

    I have seen many comments to the effect that this does not necessarily work, the module is still loaded…can anyone comment definitely??

    Thank you, Tom

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About the author

Duncan Epping is a Chief Technologist in the Office of CTO of the Cloud Platform BU at VMware. He is a VCDX (# 007), the author of the "vSAN Deep Dive", the “vSphere Clustering Technical Deep Dive” series, and the host of the "Unexplored Territory" podcast.

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