In this post we will continue covering the storage objective from the blueprint.
The following are the blueprint objective:
- Differentiate NFS 3.x and 4.1 capabilities
- Connect an NFS 4.1 datastore using Kerberos
- Differentiate Physical Mode RDMs and Virtual Mode RDMs
- Create a Virtual/Physical Mode RDM
- Configure Bus Sharing
- Configure Multi-writer locking
SIOC: (i skipped some parts of the blue print because i didn’t study the marital yet such as “Differentiate between SIOC and Dynamic Queue Depth Throttling features”)
- Describe the benefits of SIOC
- Enable and configure SIOC
- Configure/Manage SIOC
- Monitor SIOC
NFSv3 and NFS4.1:
VMware support both NFS protocols here are the differences between the two:
- Traffic is unencrypted
- Use only one TCP connection for I/O.
- ESXi has No support for delegate user functionality
- Supports hardware acceleration and integration with NAS devices
- Locking on ESXi does not use the Network Lock Manager (NLM) protocol (use VMware locking)
- Support multipathing for servers that support session trunking, use of multiple IP addresses to access a single NFS volume
- Does not support hardware acceleration.
- Supports the Kerberos authentication protocol to secure communication with the NFS server.
- Uses share reservations as a locking mechanism, and have build in file locking(no need for VMware locking
- supports nonroot users to access files when used with Kerberos
Not all VMware features currently support by NFSv4 , THIS WILL CHANGE WITH FUTURE VERSIONS!!!
Connect an NFS 4.1 datastore using Kerberos:
- ESXi Hosts need to be part of the Active directory
- Need to configure user that have credentials to authenticate with the kerberos server
I included only the screenshots that are different from NFSv3:
An RDM is a mapping file in a separate VMFS volume that acts as a proxy for a raw physical storage device. The RDM allows a virtual machine to directly access and use the storage device. The RDM contains
metadata for managing and redirecting disk access to the physical device.
There are two modes of RDM :physical and virtual
Physical Mode: Allows the guest operating system to access the hardware directly. Physical compatibility is useful if you are using SAN-aware applications on the virtual machine. However, a virtual machine with a physical
compatibility RDM cannot be cloned, made into a template, or migrated if the migration involves copying the disk.
Virtual Mode: Allows the RDM to behave as if it were a virtual disk, so you can use such features as taking snapshots, cloning, and so on. When you clone the disk or make a template out of it, the contents of the LUN are copied into a .vmdk virtual disk file. When you migrate a virtual compatibility mode RDM, you can migrate the mapping file or copy the contents of the LUN into a virtual disk.
Create a Virtual/Physical Mode RDM:
Before I add a new RDM drive in my lab i will need to create more LUNs in my Windows server and than i need to re-scan for the new disk
On the vm setting click on new device >> RDM disk and click add.n
Choose the new LUN and click Ok.
Choose physical or virtual RDM:
Configure Bus Sharing and Configure Multi-writer locking:
Bus Sharing: Under the SCSI controller section you can configure SCSI Bus Sharing
Multi-Writer: under Sharing you can configure Multi-writer
Storage I/O Control
Describe the benefits of SIOC:
Storage I/O control its like QOS for your datastore , you can control the amount of I/O per VM during period of I/O congestion.When you enable SIOC the ESXi host start to monitor the latency and when a latency threshold reached SIOC allocate resource in proportion of their shares.
Enable and configure SIOC:
by default SIOC is disabled to enable SIOC on a datastore: Click on the datastore >> Manage>>Setting >> General >> Edit
You can configure % peak throughput or adjusted to manual when you can actually control the latency.
Once SIOC is enable you will be able to configure the Shares and I/O limits for a specific VM,
To monitor SIOC resource allocation (Shares and Limits) go to Datastore >> Related Objects>> Virtual Machines.
Thanks for reading