ESXi 6.7 Datastore Maximum Size and Dell R740xd2 RAID

[Evan55]

First question:

What is the maximum size Datastore I can create in vSphere 6.7?

From what I can tell its 64TB, right?

However I was able to add a datastore of ~260TB to my environment today, before I stopped to think if this was even possible. vCentre gave no warnings or errors and happily created the datastore for me. If the maximum is 64TB how is that possible? I have since removed it to be safe.

Second question:

If I have to split the datastore up in smaller chunks, what is the best way to do it without losing tons of wasted space?

All storage is via a Dell R740xd2 server with 20x... 16TB 7.2 RPM 12Gbps SAS drives. I also have 4x... 3.84TB SSD drives but those aren't an issue for this scenario.

Ideally I wanted all HHD in one RAID 6 array presented to VMware but that now seems impossible. I also cant provision multiple datastores from that single RAID presented from the Dell

This box is going to be used primarily for backups, restore and test platform if my vSAN cluster hits a wobble or needs offline maintenance for whatever reason so space is more important than anything else.

So I was hoping to have the full size Datastore available to me. Some of my individual VMs are also fairly large ~40TB or so and I want a long GFS backup retention periods

As this is not a SAN but just using the PERC H730p controller in the Dell R740xd2 - I cant see a way to create a single RAID 6 array and then multiple LUNS from that array to present to vSphere.

Which means I have to create multiple RAID 6 arrays from smaller number of individual disks which means that I lose a LOT of wasted space compared to one single RAID 6 array.

Can anyone tell me if I have completely missed the mark and there is an better way to do this?

[depping]

64TB is indeed the maximum we support as documented here: https://configmax.vmware.com/guest?vmwareproduct=vSphere&release=vSphere%207.0&categories=2-0

I agree that it the UI should call out that the LUN is larger than the maximum size, I will file a feature request / bug fix for you for it. Please note though, the H730P also officially doesn't support LUNs larger than 64TB!

You don't have many options as far as I can see, other than creating multiple logical devices.

[IRIX201110141 · Accepted solution]

Second Question:

Within the iDRAC or LCC and the configuration of the RAID you can for sure create a single RAID 6 diskgroup with one large 260TB Virtual Disk or you can create multiple Virtual Disk on that one diskgroup by just editing the size of the VD which is always prefilled with the 100% value by default.  This ends in multiple LUNs and ESXi can create independed Datastores on. You dont waste any space with that kind of setup.

If possible create all VDs with slightly different sizes so you can identify them on PERC and also on ESXi level.

Otherwise document the LUNS and use the name for VD on PERC Level as in ESXi for Datastore. You can edit the names of the VD later. Consider to install the small OMSA vib on your ESXi which gives you access from a full blown OMSA installation on a Windows/Linux box to the Dell HW on ESXi from HostOS perspective.

Note: The Term Virtualdisk(VD) referrers to the PERC and not VMDK/VM or so.

Regards,
Joerg

[Evan55]

Thanks Duncan for the feedback and thanks also for confirming I wasn't going mad wondering why it allowed me to create a datastore more than 4x the max limit

I appreciate you logging that bug fix with the team.

Do you think they will increase that 64TB limit in future?

Edit: typo

[Evan55]

Thank you Joerg - I managed to create multiple virtual disks from the single large RAID 6 array in the Dell config. Dell really don't make their RAID config very intuitive so I did a combination of changes via the boot setup and other changes via the iDRAC GUI but eventually got there in the end.

In the end I created 4 Virtual Disks 60TB, 59TB, 58TB, 57TB and then a 20TB.

Thanks for the tip on creating them with slightly different sizes to easily identify in future. This is clearly coming from experience so thanks for passing that one. I will also mimic the naming of the VDs and the Datastores too.

Thanks again for both of your assistance on this.

[IRIX201110141]

depping​

The documentation of OMSA says there is no size limit for a virtual disk for H710 and later PERCs.

Evan55​

One drawback is when using multiple VDs within a Diskgroup is that you cant increasing the Diskgroup/Raid  by adding Disks any more.  But with a full populated XD2 this isnt a issue i think

I miss the old "dos" like PERC menu which i have used for 15 years  or so.

Regards,
Joerg

[Evan55]

Thanks Joerg for the heads-up with regards not being able to increase the diskgroup/RAID which shouldn't be too much of an issues like you said as my R740xd2 is pretty much maxed already.

What I am hoping to do though is extend individual Virtual Disks if possible using the existing diskgroup.

I have left a small amount of unused space ~7TB that I am hoping to extend any of the existing virtual disks should emergency measures be needed if one Datastore maxes out for whatever reason.

I dont have the option in the iDRAC GUI to do this at the moment on those specific virtual disks but I'm kinda hoping its because they are still initializing in the background. I hope when that's done it will give me that option. If not then I am kinda wasting that 7TB and should either create a new 7TB virtual disk or kill the 20TB virtual disk and recreate it as 27TB

[IRIX201110141]

Hmm.... i think you cant extend a VD in that way. Maybe the last one.... or for sure deleting one and creating a new one form scratch but that kills the data on that VD.

Its very similar to Windows  Partitions/Filesystem on a single phys. HDD/LUN. You cant resize the first or middle one... only the last

If you have ESXi on dual SD? Consider of creating a 130GB VD and install ESXi on because of the changed partition theme and the OS_DATA with ESXi 7.0.

Our XD2 are "Holding Tanks" for VEEAM and storing ESXi VM backups.

Regards,
Joerg