Saturday, 20 March 2021

VVOLs, Oracle Database, Performance, and ONTAP – Some Research Links

Below are some research links and notes I jotted down regards the topic of, VVOLs, Oracle Database, Performance, and ONTAP. I should strongly point out that I am not an Oracle expert, I am also not particularly expert on many other things too! This is just my way of getting some thoughts and ideas together.

1) [VVOLs & Oracle] A Cracking VMware Whitepaper:

Virtualizing Oracle Workloads with VMware vSphere Virtual Volumes on VMware Hybrid Cloud | REFERENCE ARCHITECTURE
https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/whitepaper/solutions/oracle/vmware-oracle-on-virtual-volumes.pdf

From a performance perspective I didn't get much from this whitepaper, but it is great that it exists, since it validates an Oracle on VVOLs approach.

2) [Oracle & Performance & ONTAP] Words of Steiner:

Jeffrey Steiner is the Oracle on ONTAP king. I couldn't find anything relating to VVOLs on his blog but there is this:

NetApp NVMe for your database
https://words.ofsteiner.com/2018/08/24/netapp-nvme-for-your-database/

Down the bottom of the post he presents some statistics from an actual AWR report, and you see what NVMe-oF can do.

Alas, VVOLs are not currently supported on NVMe-oF as per:
Requirements and Limitations of VMware NVMe Storage

3) [Oracle & Performance] Oracle AWR:

I know little about Oracle AWR, but this PDF slide-deck looks very interesting:

Oracle: Using Automatic Workload Repository for Database Tuning: Tips for Expert DBAs
https://www.oracle.com/technetwork/database/manageability/diag-pack-ow09-133950.pdf

4) [VVOLs & Performance & ONTAP] NetApp Verified Architecture:

NetApp Verified Architectures are always worth a look. No Oracle is this NVA, but a little about VVOLs, a little about performance, and of course a big bit about ONTAP.

Modern SAN Cloud-Connected Flash Solution: NetApp, VMware, and Broadcom Verified Architecture Design Edition: With MS Windows Server 2019 and MS SQL Server 2017 Workloads
https://www.netapp.com/pdf.html?item=/media/9222-nva-1145-design.pdf

The '4.5 Workload Design' section talks about:
We used the 3SB tool to create an 800GB SQL Server database. We spread the database across five 200GB VMDK files, and one additional 200GB VMDK to handle the database log activity. For the FCP environment, we deployed six 250GB LUNs on each of the 14 SQL Server hosts. We created one LUN per volume and one VMDK per LUN. For the NVMe/FC environment, we created three 1.46TB namespaces per SQL Server host, but used two VMDKs per namespace.”

The '5.1 Test Methodology' section talks about:
As ONTAP systems are designed for multiple workloads and tenants, best performance is obtained when at least four FlexVol volumes are used per node.”

5) [Performance & ONTAP] Justin Parisi:

There are a few important things to understand about ONTAP & Performance, this is covered well by Justin Parisi in these links:

Volume Affinities: How ONTAP and CPU Utilization Has Evolved
https://blog.netapp.com/volume-affinities-how-ontap-and-cpu-utilization-has-evolved/

NetApp ONTAP FlexGroup Volumes: Top Best Practices: TR-4571-a
https://www.netapp.com/pdf.html?item=/media/17251-tr4571a.pdf

NetApp ONTAP FlexGroup Volumes: Best Practices and Implementation Guide: TR-4571
https://www.netapp.com/pdf.html?item=/media/12385-tr4571pdf.pdf

A couple of extracts:

In ONTAP 9.4 and later (high-end platforms):
- Each volume has one affinity.
- Each aggregate has eight affinities
- Nodes have a maximum of 16 affinities.
One member volume per available affinity is created. In ONTAP 9.4 and later, up to 16 member volumes per node are created in a FlexGroup volume.”

To support concurrent processing, ONTAP assesses its available hardware at startup and divides its aggregates and volumes into separate classes called affinities. In general terms, volumes that belong to one affinity can be serviced in parallel with volumes that are in other affinities. In contrast, two volumes that are in the same affinity often must take turns waiting for scheduling time (serial processing) on the node’s CPU.”

6) [VVOLs & ONTAP] Rebalancing VVOLs Datastores:

This link has good info in:

Rebalancing vVols datastores
https://docs.netapp.com/vapp-98/index.jsp?topic=%2Fcom.netapp.doc.vsc-iag%2FGUID-C9FEA419-BDDF-4B9B-837C-0D64CC136FA3.html

All vVols associated with a virtual machine are moved to the same FlexVol volumes”

7) [VVOLs & ONTAP] Flexpod Design Guides:

Flexpod desing guides are always useful because of the high amount of technical detail. Not particularly useful for my research but there is a bit of VVOLs on ONTAP in here:

FlexPod Datacenter with VMware vSphere 7.0 and NetApp ONTAP 9.7
https://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/UCS_CVDs/fp_vmware_vsphere_7_0_ontap_9_7.html

SUMMARY / CONCLUSION

From this little bit of research, sonething becomes apparent. If you're after the most extreme Oracle performance you can get, then VVOLs are not going to be the best option:

1) VVOLs are not supported by VMware on NVMe-oF, so you can't benefit from NVMe-oF.
2) All VVOLs associated with a virtual machine are in the same FlexVol, so you can't benefit from using multiple volume affinities.

So you need to ask yourself, is the performance you get from your Oracle on VVOLs testing sufficient for your needs?
If it is then excellent, if not then don't use VVOLs and instead benefit from NVMe-oF and spreading your workload over multiple volume and aggregate affinities.


PS: "Vdbench is a command line utility specifically created to help engineers and customers generate disk I/O workloads to be used for validating storage performance and storage data integrity. Vdbench execution parameters may also specified via an input text file.":
https://www.oracle.com/downloads/server-storage/vdbench-downloads.html

PPS: Something also to bear in mind from this NetApp Documentation:
Unified Manager 9.7 Documentation Center (netapp.com)
"When there is minimal user activity in the resource, the available IOPS value is calculated assuming a generic workload based on approximately 4,500 IOPS per CPU core."

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