question about growfs, aac raid, enlarging by adding disks

Scott Long scottl at
Tue Apr 27 19:05:44 PDT 2004

Don Bowman wrote:

> this is perhaps a naive question, but i
> couldn't find the answer.
> if i have e.g. a 3-disk raid5 using aac,
> and i add another disk, can i increase the
> size of the logical disk using the aac bios
> (or ideally aacli), and then use growfs to
> increase the size of the filesystem? Can
> this be done if i obey some restrictions,
> e.g. resize the last filesystem on the partition?
> I would like to boot from the array, have swap
> on it, and have a large partition that uses
> the remainder of the space. I'm assuming i would
> lay it out so that it goes root first, then
> swap, then the large filesystem.
> The adaptec raid bios seems to indicate i can
> grow by adding a drive, but only under windows.
> The manual for it has no mention of this. The
> datasheet also indicates i can increase size
> 'on the fly'.

aaccli will let you increase the size of the container.
If you are using Windows, then there is magic that will
resize the partition table and the NTFS and/or FAT
filesystems.  I can't remember if the magic is in the
driver, aaccli, or firmware, but it definitely only
applies to FAT and NTFS _filesystems_.  Growing the
container is done in the firmware and is independent
of the filesystems, MBR/slice table, etc.

> Does vinum enter into this? ccd? Since the raid
> is done in hardware i wouldn't think so.

neither vinum nor ccd apply here.  A true LVM might
be nice, but vinum doesn't provide the kind of LVM
services that would help here.

> It would appear that i might be able to add
> a disk, convince the raid to increase in size
> somehow, rerun fdisk to increase the size of
> my partition, rerun bsdlabel to increase the 
> size of my slice, and then run growfs.

I agree with this.  Of course, nothing beats a good
backup first =-)  Let me know if you need help with
the aaccli magic.

> this is all on 5.2.
> Anybody else ever done this?

Years ago I tried it and was somewhat successfull, but
it was more of a proof of concept than anything else.

> --don


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