Thanks for the responses everyone. Just
to confirm...
...WAFL does indeed stripe each flexvol
across all disks in the aggregate. If you have a flexvol that's 5%
of your total aggregate space, it's safe to conclude that it's using 5%
of each disk in your aggregate (assuming aggregate disks are all the same
size). This was the impression I got from the documentation and then
confirmed by the group.
...We don't have any mixed performance
disks in our system (everything is 10K RPM), just mixed sizes. Creating
a separate RG for each disk size is a good idea; this prevents wasting
any larger disks on parity for smaller ones. Thanks for the suggestion.
It seems we still have some confusion
around what happens with performance in this mixed-disk scenario as well
as the impact of a single aggregate spanning multiple FC adapters. Can
anyone from NetApp clarify these for us?
Jeff Mery - MCSE, MCP
National Instruments
-------------------------------------------------------------------------
"Allow me to extol the virtues of the Net Fairy, and of all the fantastic
dorks that make the nice packets go from here to there. Amen."
TB - Penny Arcade
-------------------------------------------------------------------------
I think wafl stripes across all disks in an aggregate.
I'm not sure how it respond to having one raid group
with larger disks - likely it will not use part of them.
I'm pretty sure netapp recommends all disks in an aggregate
be the same size, or, it will assume they are all the size of the
smallest disk.
Of course, I could be wrong . . .
David
> Remember that WAFL still writes across the entire aggregate. Having
a
> slower RAID group in an aggregate of faster raid groups would be akin
to
> having a slower disk in a RG of faster disks, would it not?
>
>
>
> Glenn
>
>
>
> ________________________________
>
> From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com]
> On Behalf Of Brosseau, Paul
> Sent: Wednesday, September 20, 2006 8:05 PM
> To: Jeff Mery; toasters@mathworks.com
> Subject: RE: Mixed disk sizes within a single aggregate
>
>
>
> Mixing disk sizes in an aggregate is not a problem as long as you
create
> RAID groups for each kind of disk. WAFL creates stripes at the
RAID
> group level. For best results create complete RAID groups each
time you
> add disks to an aggregate.
>
>
>
> Paulb
>
>
>
> ________________________________
>
> From: Jeff Mery [mailto:jeff.mery@ni.com]
> Sent: Wednesday, September 20, 2006 3:30 PM
> To: toasters@mathworks.com
> Subject: Mixed disk sizes within a single aggregate
>
>
> Greetings fellow toasters!
> <Background>
> We're looking at moving our 2 FAS940 systems from tradtional volumes
to
> flexvols + aggregates.
> </Background>
>
> It would seem to me that the same rules and guidelines for creating
> traditional volumes now apply directly to the aggregate level (for
the
> most part). By rules and guidelines I mean things like trying
not to
> mix disk sizes, try to avoid volumes (now aggregates?) that span FC
> adapters, etc.
>
> Are any of these things still a concern on modern versions of ONTAP
> (7+)? Does anyone have any best practices they'd be willing
to share in
> regards to aggregate creation? NOW says "make them as big
as possible
> using as many spindles as possible", but that doesn't really
help much.
> We use our filers for unstructured data only; cifs + nfs but no
> databases, no snapmirror, no snapvault, etc..
>
> TIA,
> Jeff Mery - MCSE, MCP
> National Instruments
>
> ------------------------------------------------------------------------
> -
> "Allow me to extol the virtues of the Net Fairy, and of all the
> fantastic
> dorks that make the nice packets go from here to there. Amen."
> TB - Penny Arcade
> ------------------------------------------------------------------------
> -
>