[linux-lvm] Total free space using added VGs and LVs

Stuart D. Gathman stuart at bmsi.com
Mon Oct 26 19:39:54 UTC 2009

On Mon, 26 Oct 2009, Lou Arnold wrote:

> Hat do you mean by:"4) switch root (remount won't be good enough since it
> changed "underfoot")"
> Can you please explain?

You can't change a filesystem by directly writing the block device while
it is mounted, without hopelessly confusing the filesystem driver. 
(Exceptions would be filesystems designed to be updated by multiple
computers - but these have their own limitations.)

Switchroot actually closes all files, umounts root fs, and mounts it again.
It is normally used at the end of initrd to switch from the ramdisk root
to the real root filesystem.  Not much better than a reboot actually,
but technically not a reboot :-)

	      Stuart D. Gathman <stuart at bmsi.com>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.

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