RAID-5 expansion / harddisk replacement (with bigger disks) without total data-loss

Johnathan Conley jdc at
Tue Aug 26 17:06:37 CDT 2003

I agree - if this is your only 24x7 machine - I would not trust the on-board controller for what you are proposing. Maybe if you had an EMC disk system and the online tools to manage such a fiasco.
If you're in a real bind - call Dell support and they'll likely say the same - I wouldn't expect a guarantee. This is a linux mailing list after all you know.

-----Original Message-----
From: jason andrade [mailto:jason at] 
Sent: Tuesday, August 26, 2003 4:53 PM
To: René Hoffmann
Cc: Johnathan Conley; 
Subject: Re: RAID-5 expansion / harddisk replacement (with bigger disks) without total data-loss

On Tue, 26 Aug 2003, [ISO-8859-1] René Hoffmann wrote:

> That´s the problem - by various reasons we don´t have
> this second machine available.

borrow or lease the second machine.

> Has anybody a detailed answer for my serious question
> below ?

sure. but i believe lots of people have given answers but
it is not the answer you want to hear ?  at the end of
the day i am sure there is enough power in the raid controller
interface to do what you would _like_ to do.  is it risky?
almost certainly.  all the advice i have seen is that most
people consider it _too_ risky based on their experience.

i'm sure we wouldn't mind you trying it out and proving us
wrong though..

> > Is it risky:
> >
> > 1) to replace one 9GB disk with a 36GB ?

it is not inherently risky to replace a 9G drive with a 36G
drive - you are only going to be able to use 9G of it though.

> > 2) to replace more than one disk with a 36GB ?

as above.  the 36G drive will just be treated as a 9G one.

> > 3) to replace even the last disk with a 36GB ?

as above.

> > - if it´s safe to do that until now, we would
> >   have a 9GB container on 36 GB disks -
> >
> > 4) to grow the container size ?

this is not recommended/not easily possible.

> > - if that´s the point: what could we do alternatively -
> >
> > 5) create another container on the left 27GB unused space ?

this may be theoretically possible but i don't think it would
be easily achievable.  it may be that to use the 36G drive 'in
full' rather than as a replacement for a 9G drive you would
have to initialize the drive completely and configure it
etc.. this may not happen if you put one in simply to replace
a 9G drive - it may only use the first 9G of the 36G drive.

hmm, i may be able to test this on one of our dev machines.. will
try and let you know how i go.



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