gvinum drivegroups and concat command

[Ulf Lilleengen]

On tor, aug 24, 2006 at 06:53:39 -0500, Eric Anderson wrote:
> On 08/14/06 02:31, Ulf Lilleengen wrote:
> >Hi,
> >
> >I'm doing work on gvinum these days, and I've implemented a possibility of
> >drivegroups. It is possible to add drives to group at creation, but it 
> >will also
> >be possible to add drives to groups afterwards. The advantage with 
> >drivegroups
> >are not very big right now, but I've started to work on the first command 
> >that
> >will take utilization of drivegroups.
> >
> >The concat command creates a concatenated volume, and from old vinum, it 
> >uses
> >drives as parameter. With drivegroups one can now still specify drives, or
> >groups or you don't even have to specify anything but the size, as gvinum 
> >then
> >will use the default drivegroup and create a volume for you there.
> >
> >This is how i think the concat command should be like:
> >        - if name not specified, use drivegroup-volnum (maybe 
> >        somethingelse)
> >        - size must be specified, or maybe a "fill drives/group" argument?
> >        - if group specified, it tries to create subdisks on all drives in 
> >        the
> >          drivegroup.
> >        - if drivegroup not specified, and neither drives; use
> >          defaultdrivegroup.
> >        - if drives specified, use them. overrides drivegroups.
> >
> >The general usage will be:
> >concat [-f] [-n name] [-v] [-g group] [drives]
> >
> >Further advantages with drivegroups can be the mirror and stripe commands, 
> >as
> >well as the possibility to move drivegroups between different machines and 
> >group
> >your drives into logical collections. There will be more on this later.
> >
> >If anyone have any suggestions, I would like to hear it, as I'm starting on
> >implementing these commands now and think it's very important that it's 
> >being
> >done right. If I have overlooked anything, feel free to comment. Other
> >improvements in gvinum is mentioned in the lastest status report.
> >
> 
> Will you also be able to remove/move drives from drivegroups?
> 
> This sounds like a neat feature.
> 

Yes. There are a lot of possibilities in drivegroups. It's inspired a bit from
diskgroups in the veritas vm. The concept is very similar, but veritas vm works a
bit different from vinum so not all features of veritas diskgroups will be much
of a use in gvinum. I named it drivegroups simply because we use drives, not
disks in gvinum.

There are some administrator papers on veritas which shows what can be done with
them: http://docs.sun.com/app/docs/coll/VERITAS_SF_4_0

The most relevant part is in the VERITAS Volume Manager 4.0 Administrator's
Guide, which shows what diskgroups can be used for. 

-- 
Mvh Ulf Lilleengen
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