Flashpools and FlashCache with newly announced FAS2650 and FAS8200

[Matt99]

AFAIK, flashcache is not used when a flashpool aggregate is in use (at least for the flashpool accelerated aggregate).

It looks like the latest FAS line now includes NVME flashcache in all models.  I wonder if the same limitation exisit?.

It would seem odd to include fashcache in every model when in most models it would go unused (ie I imagine most units sold are hybrid or AFF).

Does anyone know of the interplay between the new NVME flashcache and Flashpool is different with ontap 9.1 and these new units?

[colin_graham]

There was some info on this in the most recent Netapp podcast about the new hardware.

Flashcache and Flashpool work together in Ontap 9.1, and Flashcache usage is used to better predict what should go in flashpool.

[River]

Hi All :

I am installing FAS9000 now, and I can not find out any KB about NVME modules.

Do I need to setup the options like old PAM did?  ex: options flexscale.xxxx 

And how can I predict the module's life?  For SSD is shelf, I can use storage show disk in node shell.

And if the NVME module failed, will it cause performance issue?

And what's Quad-path  used for? Only more safety?  Should I cable as Quad-path  right now?

There's not too much information I can found on NOW site...

And I had AFF700 need to install about a month later = =.

[andris]

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@River wrote:

Hi All :

I am installing FAS9000 now, and I can not find out any KB about NVME modules.

Do I need to setup the options like old PAM did?  ex: options flexscale.xxxx 

Andris: Even though we evolved from PCIe cards to NVMe modules in the latest platforms, it's still Flash Cache. So, it's the same commands to configure and monitor. Configuration is mostly "enable and forget".  You would use the "system controller flash-cache" commands for physical aspects and "system node external-cache" commands for the actual cache behavior configuration. The corner-case tweaking might still use the nodeshell flexscale.* options.

And how can I predict the module's life?  For SSD is shelf, I can use storage show disk in node shell.

Andris: if you look at "system controller flash-cache show -instance", the percent-online field tells you how much of the Flash memory is operational. Also, when the module is almost at its end-of-life, the system will issue EMS events and AutoSupport messages.  That said, Flash Cache modules don't really wear out before the lifetime of the platform.

And if the NVME module failed, will it cause performance issue?

Andris: Generally, yes. You'll get EMS events, alerts and AutoSupport messages sent if a Flash Cache module fails.

And what's Quad-path  used for? Only more safety?  Should I cable as Quad-path  right now?

Andris: I answered this in your other thread.  http://community.netapp.com/t5/FAS-and-V-Series-Storage-Systems-Discussions/What-s-Quad-path-used-for/m-p/127612#U127612

There's not too much information I can found on NOW site...

And I had AFF700 need to install about a month later = =.

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[unixnation]

Hi,

I too would like to see some KB articles on the flash cache and flash-pool configuration options discussed here. It would also be nice to see the documentation updated to reflect the ability to use flash pool and flash cache together e.g. TR-4070 still says:

Data from volumes that are provisioned in a Flash Pool aggregate or an all SSD aggregate is automatically excluded from being inserted into Flash Cache cache

I'm also interested in finding out if 'hya caching' is supported on the FAS8020 platform and if so, any guidance on usage. It sounds like it'd bring benefits to our environment as we have controllers with 1TB flash cache and flash-pool aggregates in order to accelerate certain workloads. Obviously in that scenario the flash cache is effectively being wasted so would be great to utilise it!

Cheers,

Steve

[Matt99]

After several deployments of new FAS2650 running ontap 9.1, I can confirm that Flashcache and Flashpool do NOT work together just like prior versions.

We have deployed 4 new FAS2650 for customers all with hybrid pools.  After several months of customers every single one shows 0 hits to the flashcache.

So it would appear the NVME Flashcache in the FAS2600 line goes to waste for hybrid workloads.

-M

[unixnation]

Thanks for the response. Disappointing news though 😞

[andris]

@Matt99

Have you opened a case with NetApp Support concerning this?

Verify your flexscale options on these nodes.

::> node run -node <name> options flexscale

In particular, verify that flexscale.flash_pool_caching is on.

(and make sure it's enabled, rewarm is on, etc.)

[andris]

Actually, you should view and modify the external cache options via clustershell, instead.

system node external-cache show

Check that -is-hya-enabled  is true.

system node external-cache modify, if necessary.

Ref: man page

[Matt99]

Yup, support had us check the same settings.  They are set correctly but the hit rate always shows 0.  

So at least on the several units we have deployed, it hasn't been useful.

[arnout]

HI,

Did you log a support case for this?

If so? Can you share with me the nr?

Cause the documentation states they are working together?

And found out that you are not the only one reporting this.

Thanks!

Arnout

[unixnation]

Just following up on this old post as I realised I never closed the loop. Not sure if @arnoutyour question was directed at me - we were well into procuring new FAS8200 systems in Feb.

Now we have a mixed FAS8020/FAS8200 cluster on 9.1p11 whilst we migrate our data, I can report that the 8200s have hya-caching set to true, old 8020s have it set to false still. Leaving this issue now as the problem will be resolved for us now by the new hardware.

Cheers,

Steve

[unixnation]

Hi,

So in contrast, is-hya-enabled is set to false on our FAS8020 systems.

@andris So obviously it looks as though that should be set to 'true' from the man page however is this supported on an 8020? Should I be following this up through support?

@Matt99 shame if they can't be used together. Was that the expectation from sales?

Cheers,
Steve

[andris]

The "use both" feature should be supported on any platform that has both Flash Cache and Flash Pools - it's platform agnostic.

Again, if this doesn't appear to be working, I'd open a case to investigate.

[Matt99]

Well, we are sales, so we did not have any expecation when selling the units to customers.

These unitls would have been sold even if it didn't have the NVME flash modules so its not like we promised preformance gains from it.

But it would have been nice to see a real benifit, rather than a pre-sales line item.  I'm sure a pure HDD aggrgate would get some use, but we do few of those these days.

And just to confirm, we always check that hya-caching is set.  Here is a screenshot of one unit that always stays at 0 hits.