I think this is still true; I don’t have the exact details, but you can, of course, add an SSD only aggregate to an existing filer,
but you should always try to keep different storage tiers on separate controllers.
F.ex. if you want to run SAS, SATA and SSD aggregates, you should have a 4-node cluster with an AFF HA pair, and one pair where one
of the controllers is serving SAS primarily and the other is serving SATA.
There are multiple reasons (so I’ve been told) for doing that, one of the most important being that especially on AFF systems, a lot
of internal configuration values and timeout settings have been removed which were designed for disk-based systems, because they simply do not apply for all-flash systems.
When you mix SAS and SATA aggregates on the same controller, please keep in mind that both are running off the same consistency point,
so slow SATA writes will automatically also slow down your SAS write throughput – and that will even be worse when you mix up SATA and SSD aggregates on the same controller.
Personally, I try to avoid mixing storage tiers on one controller because what has been told to me by some of the NetApp Techs on several
occasions and what I’ve read about mixing workloads and disk types etc. sounds reasonable enough to just not do it if not absolutely necessary.
Best,
Alexander Griesser
Head of Systems Operations
ANEXIA Internetdienstleistungs GmbH
E-Mail:
AGriesser@anexia-it.com
Anschrift Hauptsitz Klagenfurt: Feldkirchnerstraße 140, 9020 Klagenfurt
Geschäftsführer: Alexander Windbichler
Firmenbuch: FN 289918a | Gerichtsstand: Klagenfurt | UID-Nummer: AT U63216601
Von: toasters-bounces@teaparty.net [mailto:toasters-bounces@teaparty.net]
Im Auftrag von Mike Gossett
Gesendet: Mittwoch, 29. März 2017 16:16
An: John Stoffel <john@stoffel.org>
Cc: toasters@teaparty.net
Betreff: Re: FAS2552 -> FAS8200 migration
Just based on what I was told by a NetApp sales rep. Very glad to hear that this is a supported configuration. It had been explained to me ~6-8 months ago that all-ssd aggregates were only supported by AFF systems, which would not support
hybrid or spinning disk shelves, and that if one needed an all-ssd aggregate (flash-cache\pool not sufficient) , adding an AFF HA pair to a cluster was the only way to go
On Tue, Mar 28, 2017 at 6:37 PM, John Stoffel <john@stoffel.org> wrote:
>>>>> "Mike" == Mike Gossett <cmgossett@gmail.com> writes:
Mike> I don't know if it really makes it any more or less simple. If
Mike> you are going to end up with a long term SAS disk footprint,
Mike> then if it were me, i'd rather be using those SAS disks for my
Mike> root than SSDs. Sounds like you're going to have at least
Mike> 20x900G SAS disks in your end-state configuration, so you might
Mike> want to evaluate buying another some more SAS disk to hold
Mike> that.
Mike> I haven't looked at the latest changes, but historically you had
Mike> the choice of AFF or flash-pool \ hybrid aggregates. Are you
Mike> sure that you are going to be able to have an all-flash shelf on
Mike> the same system as hybrid \ spinning-disk shelves? As of 6
Mike> months ago, this didn't fly. *
I don't know why you think so. I've been running an 8060 four node
cluster with a shelf of SSDs with most of them in an aggregate, along
with a couple or three disks (I forget) were setup in a FlashPool.
But since we also had FlashCache, it was explained to us that they
didn't really work like we thought/wanted, so we just nuked the
FlashPools and added the disks back into the SSD aggregate.
John