Yellow Bricks

by Duncan Epping

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.

Reader Interactions

Comments

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

  4. 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. 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. 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

  9. 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. 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