Question on vSAN

[ManivelR]

Hi All,

I need yours advice and suggestion on vSAN.

My setup is as follows:

2 clusters with vSAN in single datacenter.

1st management cluster-->3 supermicro ESXi servers--> ESXi version 6.0.0 U2 with vSAN 6.2.   vCenter server 6.5.0 ,DB,vROPS,vCD,NSX etc.. All will be located on vSAN data store.

3 supermicro servers * 500 GB of local hard disk(each ESXi server) === 1500 GB of hard disk.

Only one disk group--> 200 GB SSD(each ESXi server) + 2* 150 GB SATA/SAS(each server)== 500 GB.

2nd customer cluster---> 10 supermicro ESXi servers--> ESXi version 6.0.0 U2 with vSAN 6.2.Customer virtual machines will be running with vSAN data stores.

10 supermicro servers * 5 TB local hard disk(each ESXi server) === 50 TB hard disk.

Each ESXi server has 4 TB SAS/SATA and 1 TB flash drive(SSD)== 4 + 1 TB

Going to create 2 disk groups with 500 GB each(SSD drive) + 2 TB SATA/SAS.

i.e   1st disk group  is 400 GB SAS + 2 TB SATA/SAS and 2nd disk group will be 400 GB SAS + 2 TB SATA/SAS   ====  5 TB

10 ESXi servers--> 2 disk groups(each ESXi server)---> 50 TB hard disk.

Is this design is ok to proceed?  

If i create 2 disk groups,then 2 vSAN data stores will be created ? Am i right ?

In a single vCenter server,may i create 2 clusters along with vSAN and then can be used ? is this recommended one ?

Please check and suggest.

Thanks,

Manivel Rajarathinam.

[IRIX201110141]

No.

One vSAN Datastore per Cluster. Even if you have multiple Diskgroups within a Hosts. All Diskgroups from Hosts within the cluster are merged into one vSAN datasore.

Yes.

A single vCenter supports more than one vSAN enabled cluster.  So thats not a problem.

In vSAN the cache (hybrid) or buffer (afa) SSD doesnt add usable capacity. I expect ~35TB vSAN Datastore,

Iam not a fan of a single SATA or  NLSAS disk for a diskgroup.  Switch to a AFA setup or add multible 10K disks. The first read have to be come from your single SATA. You may can speed up with modify the diskspanning withing the storage profile (only if you have more than one capacity drive)

Please double check that your HW is on the HCL or just use Ready Nodes.

Regards

Joerg

[sk84]

IRIX201110141​ is right.

- Only 1 vSAN datastore per cluster

- Multiple disk groups are only used for performance and availability reasons

- Each disk group must have at least one cache device (SSD)

- For performance and resilence reasons it is also recommended to have multiple disk groups with multiple capacity disks.

- It is also recommended that the capacity disks in a diskgroup are of the same type and have the same capacity and speed.

- Cache devices are not included in the capacity calculation because they serve as caches and do not store data permanently.

Please note that this is the raw capacity. The usable capacity depends on your failures to tolerate setting (FTT). In a hybrid setup you cannot use erasure coding, compression or dedup, but only a mirrored design. For example, with FTT=1 your capacity is more than halved, because 100 GB VM data will consume slightly more than 200 GB on the vSAN datastore.

It is also important to stick to the vSAN HCL. The hardware itself must be on the vSAN HCL and you must also use the recommended firmware and drivers. This is especially true for raid controllers and disks.

[ManivelR]

Thanks so much for your feedback Joerg and Sebastian.

[sk84]

Do you want to use the LSI MegaRAID SAS Invader controller for vSAN, mentioned in this thread: Question on Raid controller  ?

If so, I have to say I could not find this controller on the vSAN HCL:

VMware Compatibility Guide

It seems that this controller is not supported for vSAN.

However, sometimes these controller cards have different names and product strings (especially in vSAN ready node configurations). I would therefore recommend to double check wether it's supported or not (maybe ask the VMware support).

[ManivelR]

Hi Sebastian,

My vSAN setup is in pipline and will check the ready nodes configuration.

Raid controller question is for another vSphere environment which dont have vSAN.

Thanks so much for your answers.

Much appreciated.

[ManivelR]

Hi Sebastian,

During vSAN setup,hardware RAID configuration is not required ? Am i right ?

I just need to enable JBOD mode or RAID 0(raid setup) ?

Post vSAN setup,i need to configure the RAID configuration(RAID 5 or RAID settings)in vSAN settings.

I wanted to double confirm.

Please check and confirm.

[sk84]

vSAN supports only pass-through mode (JBOD) or a RAID0 configuration for every single disk. But this depends on the raid controller model.

See: Preparing Storage Controllers

If you check the vSAN HCL for your raid controller model, you will see the supported features for this controller. This can be: All-Flash (for all-flash configurations), Hybrid (for hybrid setups) and either Pass-Through or RAID0 or both.

For example:

The LSI MegaRAID 9271-8i controller in an UCS vSAN Ready Node configuration supports only RAID0: VMware Compatibility Guide - I/O Device Search

Therefore we configured RAID0 for each disk (SSD cache devices and HDD capacity devices). At the end we have 16 virtual disks with RAID0 from the controller's point of view.

For some LSI controllers there is also a specific KB article for the vSAN configuration: VMware Knowledge Base

Another cluster of us has HPE Smart Array E208i controllers that support Pass-Through mode: VMware Compatibility Guide - I/O Device Search
So, we have set the controllers to pass-through mode.

But this raid controller configuration must be made before you claim the disks for vSAN.

In the vSAN world you will also read about RAID-0, RAID-1, RAID-5 or RAID-6. This is a bit confusing because it has nothing to do with your raid controller settings. When you read RAID-1 in vSAN, this means that the vSAN components are mirrored (FTT setting >= 1). RAID 5/6 refers to the Erasure Coding feature of vSAN. See: Using RAID 5 or RAID 6 Erasure Coding

[ManivelR]

Thanks so much Sebastian.