Re: more disks in certain raidgroup

From: Mike Smith (mikesmit@netapp.com)
Date: Sun Nov 21 1999 - 12:07:28 EST


My comments below.

> On Nov 21, tomi.rautio@nokia.com wrote:
> >
> > Hello there,
> >
> > is it possible to add mode disks in certain raidgroup.
> >
> > I already have raidgroup 0 and 1, all disks in same/one vol0.
> >
> > Raid group0: 14 disks and group1:28 disks and I want to add more disks in
> > group0, How?
>
> Sorry you can't. To the best of my knowledge, you can only
> add disks to the raid group most recently created.
> And by the way, 28 disks in one raid group??? IMHO, that's a lot.
> What kind of reconstruct times are you seeing for that?
> I have always used 7 max. It gives pretty good reconstruct
> times.
>

This is true. The only way to change the number of disks in
the first raid group(rg0) is to destroy the volume and
recreate the volume being sure to change the raidsize option
as follows:

vol options vol0 raidsize 28

If you want 28 disks in your first raid group. I agree with
Aaron's comment about reconstruct speed. Also the larger the
number of disks in a single raid group the higher the odds
of data loss due to duble disk failure. Please be aware that if you
have too few disks in a raid group you could also negatively
affect the performance. Check this white paper on www.netapp.com

http://www.netapp.com/tech_library/3008.html

According to the "Table 4" in this technical paper 14 disks
per raid group provides optimal performance.

-- 
~~~~~~~~~~~~~~~~~
Mike Smith
mikesmit@netapp.com
http://now.netapp.com
408-822-4755
Technical Support Engineer
~~~~~~~~~~~~~~~~~

> > -- > Aaron M. Sims | "The reason why bad things happen to you is > | because you're a dumbass!" > ams@gtf.org | - Red Foreman, That 70s Show > | >



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