Low speed VSAN

[AndreyDake]

Hello, I ask for help in solving my problem, because searches so far have not led to anything.

I assembled a test bench from 3 Dell R720 hosts (integrated RAID PERC H710 Mini) in All-flash configuration. Each host has an Intel DC S4600 SSD drive, 240GB for the cache and two 480GB drives for data. Each drive in the raid is configured for RAID-0 with the following settings: Read Policy — No Read Ahead, Write Policy — Write Through, Stripe Size — 256K. Each host also has a 10GB Broadcom QLogic 57800 network card and is connected via a 10GB Ubiquiti 16XG switch. VMware ESXi, 6.5.0, 10175896 is installed.

Measurements of the read/write speed in the VM show the sad performance of 585\150 Mb/s. Measurements produce program CrystalDiskMark. Exactly the same indicators were when instead of SSD drives were regular SAS 10k drives. And also if you look at the analysis of VSANa itself, low IOPS (I attach screenshots). I tried different releases, customized images from Dell, but the result does not meet expectations. Can anyone come across a similar

[s_wieland]

Hi,

I have checked the vSAN HCL and wasn't able to find this configuration supported for 6.5.

I think the problem is caused by the RAID controller and the used RAID 0. To get best performance the disks should be presented directly to the hypervisor without a RAID controller (with cache etc) in between. Please delete the RAID 0 config and set the disks to "Non-RAID" (Path-through mode). Due to the reason that there a several different H710 available, I'm not sure if your adapter supports this configuration.

Best regards,

Sebastian

[AndreyDake]

Hello, my RAID controller does not support end-to-end access, so according to the recommendations of VmWare, the article https://kb.vmware.com/s/article/2111266 was configured via RAID-0. Today I made a measurement through HCIBench and the results in my momia are sad:
Datastore: vsanDatastore
=============================
Run Def: RD = run1; I / O rate: Uncontrolled MAX; elapsed = 3600 warmup = 1800; For loops: None
VMs = 4
IOPS = 15523.60 IO / s
THROUGHPUT = 60.63 MB / s
LATENCY = 4.1180 ms
R_LATENCY = 0.0000 ms
W_LATENCY = 4.1180 ms
95% tile_LAT = 584.5480 ms

I do not know how to diagnose another problem, I will be glad to any tips!

[therealhostman]

You'll need to add a supported HBA to the system, instead of using the perc device.

[AndreyDake]

Could you tell me how to do this? I'm still at the primary level 🙂

[daphnissov]

The PERC H710 Mini adapter is a very very poor performing adapter. It isn't even supported past ESXi 6.0 U3 (vSAN 6.2 Update 3). There may not be a whole lot of tweaking you can do here short of buying replacement (and far more capable) storage controllers to put in these hosts.

[AndreyDake]

I would like to clarify for my understanding, in normal mode, when using directly without VSAN, the speed in the VM is good, but as soon as I enter the hosts to work in VSAN, the speed drops. If it were for RAID performance, would it really be a bad speed, or would I understand something wrong?

[daphnissov]

"Normal mode" and vSAN are two totally different storage subsystems with different inner workings, so just because you see a VM operating decently in one doesn't mean it also will under vSAN. This is not a certified controller for modern vSAN versions and my recommendation is for you to replace it with one that appears on the HCL if you wish to use vSAN.