Setup and Configure Storage IO Control in VMware vSphere

When you enable Storage I/O Control on a datastore, ESXi host starts to monitor the device latency that hosts observe when communicating with that datastore. When device latency exceeds a threshold, the datastore is considered to be congested and each VM that accesses that datastore is allocated I/O resources in proportion to their shares. (by default all VMs are set to Normal (1000) You set shares per VMDK. You can adjust the number for each based on need. The default is 1000

01. Enable/Disable Storage I/O Control

02. Configure/Manage Storage I/O Control

03. Monitor Storage I/O Control

Enable/Disable Storage I/O Control:

Before we jump in I'd like to explain how storage I/O control helps to prioritize certain VMs over the others. I think it's best to check out this image from VMware which shows basically that after activating the SIOC on shared datastore and setting up the shares (at the VMDK level) on the VMs properties, the SIOC is able to prioritize those VMs over the others.

Quote from VMware:

Storage I/O Control operates as a "datastore-wide disk scheduler." Once Storage I/O Control has been enabled for a specific datastore, it will monitor that datastore, summing up the disk shares for each of the VMDK files on it. Storage I/O Control will then calculate the I/O slot entitlement per ESXi host based on the percentage of shares virtual machines running on that host have relative to the total shares for all hosts accessing that datastore.

Few limitations and requirements:

• NFS v4.1 isn't supported (it is for NFS v3).

• Storage I/O Control does not support datastores with multiple extents.

• SAN with auto-tiering has to be certified for SIOC.

• Datastores that are Storage I/O Control-enabled must be managed by a single vCenter Server system.

• Must be disabled before removing a datastore.

• Raw Device Mapping (RDM) is not supported. (it is on iSCSI NFS and FC).

• Activate at the datastore level via vSphere client or vSphere Web client.

Configure/Manage Storage I/O Control:

1. Enable Storage I/O Control for the datastore

In the vSphere Client > select a datastore > Configuration tab > Properties > Storage I/O Control, select the Enabled check box.

The advanced settings – Threshold – default value there. Check if the value is 30 ms.

2. Set the number of storage I/O shares and upper limit of I/O operations per second (IOPS) allowed for each virtual machine. Those settings at the VMDK level so you could possibly prioritize disk where your important production DB sits.

Set the threshold. More the VM is important, greater the number…… You can use the drop down or the custom and enter your value.

In case you're getting error on activating SIOC this can be due 2 reasons:

* Not having proper licensing - “ Enterprise Plus is required. Storage I/O Control (SIOC) requires Enterprise Plus licensing. Without this license, the option to enable SIOC is grayed out.

* Check that the host is installed with ESXi 4.1 or higher.

Monitor Storage I/O Control:

There is a Performance TAB to monitor Storage I/O. How Storage I/O Control handles the I/O workloads of the virtual machines accessing a datastore based on their shares.

Datastore performance charts allow monitoring:

* Average latency and aggregated IOPS on the datastore.

* Latency among hosts n Queue depth among hosts.

* Read/write IOPS among hosts.

* Read/write latency among virtual machine disks n Read/write IOPS among virtual machine disks.

From vSphere Web client > Datastore > Monitor tab > Performance tab > View drop-down menu > select Performance.

Want to download this blog as a PDF document, click the link below:

https://drive.google.com/file/d/1leVT9rkSZSWk7LCH8aV3saE_kWwAh4MJ/view

Abd El-Rahman Oreiby

Senior Data Center Engineer

Al Thuraya Security Egypt 

www.abdelrahmanoreiby.weebly.com