Just want to add one word,
as more spindles you have, as faster you can write. But if you have a graph for
spindles / speed, you get a non-linear line. The delta is decreasing but is
always positive. The delta is "feelable" for data-disk # up to 4-5, over that it
is measurable but not significant.
If you have 35 drives, I suggest:
	1 HS
	2 Parity
	32 Data Drives
That means, your raidsize will be 17 [2x (16+1)]
Take care, that if you add another shelf, you need at least 2 drives in there
(for a singe system) to build another raidgroup to your volume when you "vol add
´volume´ 1", because it is adding 2 (1 data, 1 parity).
MM
> -----Original Message-----
> From: Mohler, Jeff 
> Sent: Donnerstag, 04. Mai 2000 23:55
> To: 'Sateesh Mucharla'; toasters(a)mathworks.com
> Subject: RE: Raid groups
> 
> 
> Question:
> 
> Why would you have one large raid group?
> 
> Your mathematical chances of losing the entire volume from a 
> 2-drive failure are
> astonomically higher than if you use smaller RG's, it will 
> also take ages longer
> to rebuild a failed drive in that large of a RG instead of a 
> small(er) one.
> 
> Also consider that the small raid group will be a 
> 'bottleneck' or sorts.
> 
> Its my understanding that every CP (consistency point) that 
> is written,
> round-robins thru all available Raid Groups (RGs) in a 
> volume.  As I see it,
> that helps balance the data for when you want to read it back 
> from disk helping
> to minimize head-seek times. X amount of data will take less 
> time and disk
> revolutions to write out on the large RG, but -may- take multiple disk
> revolutions to complete on the small RG..and extend to the 
> length of time it
> would take to read the data as well.  All things being equal, 
> equal sized RGs
> would offer a more consistent performer.
> 
> A balanced set of RGs will serve you better in the long run.
> 
> -----Original Message-----
> From: Sateesh Mucharla [mailto:sateesh@ampere.nsc.com]
> Sent: Thursday, May 04, 2000 12:21 PM
> To: toasters(a)mathworks.com
> Subject: Raid groups
> 
> 
> I am buying a F760 with 35 drives (all 36GB).
> 
> As there is limitation of 28 drives per raid group ( i read 
> it NetApp Sysadmin 
> manual), i am thinking of having two raid groups one with 26 
> and the other with 
> 7 drives. Rest two will be hot spares. But i am open for 
> better configuration.
> 
> I would like to know whether i can configure all 33 drives 
> into one raid group -
> 
> Is that possible? If so what are the disadvantages. (With 33 
> drives in one raid 
> group, i loose only one drive as a parity drive - this is an 
> advantage).
> 
> Can somebody suggest a better configuration ?
> 
> Thanks
> 
> Sateesh Mucharla
> National Semiconductors
>