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

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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9 Responses to “Disabling the VMFS-2 module! Exploring the next generation of ESX”

  1. daniel says:

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

  2. Christian says:

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

  3. Scott Lowe says:

    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:

    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. 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:

    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:

    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:

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

  9. ysemenihin says:

    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

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