One of the major advantages we have seen with VVols is making a virtual disk a first class citizen on the array. We can restore, copy, replicate them (and their VMs) as storage objects were meant to be restored, copied, replicated etc.
Though one thing about virtual disks is that by default–they are not first class citizens in vSphere, VVols or otherwise. To create one, it has to be associated with a VM.
To retrieve one in PowerCLI (for example) get-harddisk requires a datastore or a VM to return a result:
About 6 months ago, my esteemed colleague Barkz blogged about our path forward with PowerShell. We have an official PowerShell SDK for managing the FlashArray–but it is limited to that: doing stuff to the FlashArray.
So to add value and make managing it within context of the layers you actually manage your infrastructure from (VMware, Microsoft, etc.) we created some value-add PowerShell modules to make it easier. Barkz talks about them here:
This post will be about managing one-off snapshots with VVols on the FlashArray with PowerCLI.
One of the still semi-valid reasons I have seen DBAs say “I dont want to virtualize because…” Is that they have simple snapshot/recovery scripts for their physical server that allows them to quickly restore DBs from snapshots. Doing this on VMFS requires A LOT of coordination with the VMware layer.
So they tell the VMware team–“okay I will virtualize but I want RDMs”. Well the VMware team says “well we’d rather die”
…and around in circles we go…
VVols provides the ability to provide this benefit (easy snapshot stuff) but still get the benefits of VMware stuff (vMotion, Storage vMotion, cloning, etc) without the downside of RDMs.
About four years ago, we (Pure Storage) released support for our asynchronous replication and Site Recovery Manager by releasing our storage replication adapter. In late 2017, we released our support for active-active synchronous replication called ActiveCluster.
Until SRM 6.1, SRM only supported active-passive replication, so a test failover or a failover would take a copy of the source VMFS (or RDM) on the target array and present it, rescan the ESXi environment, resignature the datastore(s) then register and power-on the VMs in accordance to the SRM recovery plan.
The downside to this of course is that the failover is disruptive–even if there was not actually a disaster that was the impetus for the failover. But this is the nature of active-passive replication.
In short, VMware only supported one mechanism of LUN ID addressing which is called “peripheral”. A different mechanism is generally encouraged by the SAM called “flat” especially for larger LUN IDs (like 256 and above). If a storage array used flat addressing, then ESXi would not see LUNs from that target. This is often why ESXi could not see LUN IDs greater than 255, as arrays would use flat addressing for LUN IDs that number or higher.
I recently did a VMUG webcast on VVols and there were a ton of questions and unfortunately I ran out of time and could not answer a lot of them. I felt bad about that, so I decided to follow up. I was going to send out emails to the people who asked, but figured it was simpler and more useful to others to just put them all here.
Answer: Maybe. It depends on why you are using RDMs. If it is simply to allow sharing or overwriting between physical and virtual. VVols will replace RDMs. If it is to make it easier to restore from array snapshots, VVols will replace them. If it is for Microsoft Failover Clustering, VVols are not supported with that yet. You still need RDMs. Though VMware is supposed to be adding support for this in the next release. See this post for more info. Continue reading VVol VMUG Webinar Q&A Follow Up→