> This can lead to a sad trail of tears..depending.
>
> Your new added larger drives will only participate in the full aggregate
> data stripe to the point they are the 'same size' as the rest of the drives
> in the aggregate.

I think you mean raid group here.  So long as all disks in a RG
are the same size, you don't waste any space.  You can have a RG
of 300G disks and a different RG of 600G disks in the same aggregate
and not waste any disk space.

>
>
> Data higher than that 'water mark' of 300g deep on the 600g drives, will go
> to what in effect will perform like a new aggregate of separate 300g
> drives..you wont have an aggregate wide stripe anymore above that point.
>
> For all of the other problems it can create, just make it a second
> aggregate by itself.
>
> Theres no big party foul in mixing speeds, most often, people are adding
> faster ones to slower ones these days, so the change is a net positive.
>
> If you have a massively sensitive IOPS aware application, then dont mix
> speeds DOWN any.
>
> On Fri, Nov 4, 2011 at 7:23 AM, Vervloesem Wouter <
> wouter.vervloesem@neoria.be> wrote:
>
> > There is another option, the DS4243 shelf with 15K disks.  this can be
> > 300GB / 450GB / 600GB.
> > It is possible to mix RPM's in an aggregate / raidgroup but this takes
> > down the performance to the lowest RPM, so if you would expand the
> > aggregate I would use the same size and RPM.
> >
> > The cost per GB is one factor to count, but don't forget the performance
> > impact of bigger disks. You can put twice the amount of data on a 600GB
> > disk, but have the same amount of IOPS as a 300GB disk...
> >
> >
> >
> > Mvg,
> > Wouter Vervloesem
> >
> > Neoria - Uptime Group
> > Business Park King Square
> > Veldkant 35D
> > B-2550 Kontich
> >
> > Tel: +32 (0)3 451 23 82
> > Mailto: wouter.vervloesem@neoria.be
> > Web: http://www.uptimegroup.be
> >
> > Op 4-nov.-2011, om 15:07 heeft Joosep Meus het volgende geschreven:
> >
> > > Hi list!
> > >
> > > Currently we have 3 DS14mk4 shelves full of 300GB 3,5" 15K FC drives.
> > All drives are in a single aggregate in three raid groups with two spare
> > disks.
> > > Time has come to upgrade capacity in the aggregate and i'm thinking of 3
> > possible ways:
> > > [a] buy another DS14mk4 shelf and continue with 300GB drives - safest
> > way, but most expensive per GB
> > > [b] buy another DS14mk4 but use 600GB drives - probably good idea, not
> > so expensive as [a]
> > > [c] buy DS2246 with 600GB SAS drives - Probably not a good idea, since
> > drives are different type(in this case 2,5" 10K SAS), but it seems that
> > future will be SAS', it's cheaper per GB and takes less space in rack.
> > > As i understand, it is possible to use different drive types in the
> > single aggregate(allthough not recommended), but probably will have some
> > impact on performance.
> > >
> > > Right now my first choice would be [b] followed by [a]. If anyone would
> > share his/her thoughts on the matter I would be most grateful.
> > >
> > > Thanks,
> > > Joosep
> > > _______________________________________________
> > > Toasters mailing list
> > > Toasters@teaparty.net
> > > http://www.teaparty.net/mailman/listinfo/toasters
> >
> >
> > _______________________________________________
> > Toasters mailing list
> > Toasters@teaparty.net
> > http://www.teaparty.net/mailman/listinfo/toasters
> >
>
>
>
> --
> ---
> Gustatus Similis Pullus
>
>

Steve Losen   scl@virginia.edu    phone: 434-924-0640

University of Virginia               ITC Unix Support