HF20H througput limit

[hubert]

Hi,

we are currently playing around with a HF20H demo system equipped with 11 1TB HDDs (6,2TiB Usable) and 2 480 GB SSDs (Usable 894 GiB of Cache).

Looking at the live performance stats during various tests, we noticed that the maximum throughput seems to be limited at 200 MiB/s. The graphs show a pretty straight line.

It doesn't change anything if we use pinned volumes, disable compression/dedupe...
Is this some sort of internal limitation, or is there another explanation for this behaviour?

Tests were performed using VMs in our virtual environment on iSCSI volumes.
And also on a volume presented to a physical server.

Cabling:
We connected the onboard interfaces (eth0a and eth0b) to a 1Gb Switch, but they are configured only for management traffic (Mgmt only)
Data traffic flows through a 10GbE SFP+ card (tg1a, tg1b, Data only), and is obviously connected to a 10GbE Switch.

We are sure that the network path hits no 1Gbit bottleneck.

Can someone clarify why the throughput is limited at 200 MiB/s?

Greetings

[Nick_Dyer · Accepted solution]

Hello,

Yes, the HF20H (which is a half populated, entry model for Nimble) is limited to 200 MB/sec throughput by design. This is documented and reflected in all our pre-sales sizing tools. Note that it will still yield ~25K IOPS, which is pretty staggering for an entry model.

This is because the system has a small quantity of SSDs, and when running heavy features like inline deduplication, the SSDs will end up becoming the bottleneck, causing CPU burdening and potential performance issues. The limit is there to stop that from happening.

If you need more than 200MB/sec, but only a small amount of capacity, then a smarter investment would be the AF20Q or full-fat HF20, which can do ~1.1-1.4GB/sec throughput, respectively.

If you're a HPE partner, I emplore you to check out HPE TechPro (https://techpro.hpe.com). There are dedicated technical forums available to you which you can subscribe to.

[hubert]

OK that clears it up!

Thank you for your fast response.

[Greg LaViolette]

Follow up question if you don't mind, and the answer is probably no.

What if the HF20H is expanded with the '11TB Capacity Field Upgrade' (Q8D07B). Given the additional spindles, does that grant you some additional throuput, or are you still limited to 200 MB/sec?

Thanks for your time.

[Nick_Dyer]

Hello,

i'm afraid not - the limit still exists even if a HF20H is populated with dual RAID sets. As stated above, it's not to do with disks or spindles, it's the SSDs are still small in quantity, and this causes a bottleneck (as described above).

[BrianTKoon]

Follow up question.

Are you able to increase the size of the SSD on this model to get past the 200 MiB/s threshold, or add additional SSD drives?

[Sheldon Smith]

Sorry no. 

As written above, " the HF20H is limited to 200 MB/sec throughput by design."

Period.

[Nick_Dyer]

Hi Brian,

It IS possible to increase the performance of an HF20H - and this would be to live upgrade it to a HF40 controller. You will also need the second bank of drives populated for this to take effect.

[BrianTKoon]

They you for the response, if we were to upgrade the controller to a HF40(along with fully populating the second bank of drives), what kind of MiB limitation is there?