Expandable filesystem with more disk

[Pawel Jakub Dawidek]

On Mon, Jan 30, 2006 at 03:55:55PM +0100, Markus Örebrand wrote:
+> I need a possibility to expand a filesystem by adding more disk. I am
+> sensing that a certain GEOM setup would do the job.
+> 
+> The ideal conditions would be:
+> - The filesystem is created on a GEOM. 
+> - Initially, the GEOM has only one consumer.
+> - A consumer is a FreeBSD partition (created with bsdlabel(8))
+> - The size of the GEOM is expandable by adding more consumers.
+> - The filesystem is expandable by using growfs(8).
+> 
+> 
+> Are these conditions realistic? What is the procedure to a) do basic
+> setup, b) expand the filesystem?
+> 
+> Would this be secure (i.e. is there a risk of data corruption or -loss)?
+> I am fairly confident that the hardware should pose no security risk
+> (hardware RAID5, UPS on disks and server).

You can do it with gconcat(8). Create concatenated device with two
components:

	# gconcat label NAME ad0s1d ad1
	# newfs /dev/concat/NAME

When you want to add another disk:

	# gconcat label NAME ad0s1d ad1 ad2
	# growfs /dev/concat/NAME

With 'label' and 'create' subcommand you need to give at least two
providers currently, but now I see it will be useful to allow to specify
only one. I'll change it soon.

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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