Expanding a (hardware RAID) volume in Xpenology?


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Hi all, this is my first post on the forum.

 

My server is a Dell R230 1U rackmount server (4 drive) running a PERC H730 RAID card connected to the 4 backplane hard drive bays. I am running ESXI 6.7 Hypervisor (booted from USB) on the server.

 

I have completed some reading on the forum and proceeded with the installation using Jun's loader and luchuma's excellent "Install DSM 6.2 on ESXi 6.7" tutorial. Thanks to both for taking the time to produce these materials.

 

At present, I have been testing the system with a basic single drive (non RAID), but it is my intention to use my PERC H730 RAID card to run either a 2-disk hardware RAID1 array or a 3-disk hardware RAID5 array and then pass the full volume through the Virtual Machine which is running Xpenology. I can then presumably create a single volume in Synology using to the maximum size of the hardware RAID volume?

 

My question is:

If I subsequently increase the size of the hardware RAID volume, by adding an additional disk to the PERC H730 RAID card, is it possible to resize the volume in Synology? If so, how do I go about achieving this? For example, if I start with a hardware RAID1 (2 x 14TB drives) and use ESXI to pass this through to the Synology VM as as a single 14TB disk, what happens if I subsequently add a third 14TB disk to my hardware RAID volume and convert it to a 28TB RAID5? Can I get my 14TB Synology volume to increase to 28TB without data loss?

 

Kind regards.

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Thanks for your reply, flyride.


The hardware based Dell H730 RAID card has a 1GB cache on it, so I was operating on the assumption that I would see higher performance using the hardware RAID over software RAID. Is this incorrect?

 

Do you think I should just stick the RAID card into non-RAID (HBA mode) and get ESXI to pass through to Synology to run SHR? If so, am I passing the full controller through or just individual disks?

 

I'm assuming that if I pass through the full controller then I can't use any disk which are connected to the controller as part of any other VMs?

 

Sorry for all the questions. I have just purchased the hardware and I'm new to ESXI and Xpenology.

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55 minutes ago, HerbertJ said:

The hardware based Dell H730 RAID card has a 1GB cache on it, so I was operating on the assumption that I would see higher performance using the hardware RAID over software RAID. Is this incorrect?

 

Do you think I should just stick the RAID card into non-RAID (HBA mode) and get ESXI to pass through to Synology to run SHR? If so, am I passing the full controller through or just individual disks?

 

I'm assuming that if I pass through the full controller then I can't use any disk which are connected to the controller as part of any other VMs?

 

How much RAM do you plan to give your guest running XPenology?  Any free memory after loading the OS is cache.  All system designs are now moving the hardware interfaces closer to the CPU and PCI bus.  Controller logic is just getting in the way.

 

Regarding configuration - there are two ways to do this. You can  passthrough the controller (in HBA mode) in its entirety, and that will preclude the use of any of those disks by other guests.

 

The other way is with RDM - where ESXi retains ownership of the controller, but you select specific drives and build a Raw Device Mapping pointer for each that are then attached to the XPenology guest.  See: https://xpenology.com/forum/topic/12391-nvme-optimization-baremetal-to-esxi-report/?tab=comments#comment-88690. Any disks you don't explicitly configure with RDM may be used for scratch volumes or any other normal ESXi purpose.

 

The other issue in play is that the DSM variant you select has to support your passthrough controller.  For AHCI SATA, no big deal. For LSI, you will get the best luck with DS3615xs but some controllers aren't well supported. With RDM, there is no need for a controller driver as the ESXi RDM pointer just looks like a regular SATA drive to the guest, and can be attached to a vSATA controller.

Edited by flyride
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Posted (edited)

Thank you once again for your informative reply.

 

I had thought that the write-cache in the RAID controller would make disk writes much faster that with software as I hadn't appreciated that Synology DSM would be smart enough to utilize the system RAM as write cache. I plan to pass 8GB (or more) through to the Synology VM - so that is good to know and will definitely influence my design choices.


I would like to leave myself open to use the host for other virtual machines, so I think I may pursue the option of passing certain disks through to Synology but not the full controller. Are there any disadvantages to this approach over passing the full controller?

 

Thank you also for the link you've provided. In my test bed setup, I used the "Add Raw Disk" menu option within the "Virtual Hardware" tab of the VM configuration in ESXI to pass my desk through to the Synology DSM on Virtual SATA Controller #1 (as 1:1). I did note that the SMART functionality in DSM was not working. When I SSH to the DSM and and run "smartctl --all /dev/sdc", the disk still presents as a "VMWare Virtual Disk" with "Device lacks SMART capability".

 

It feels like perhaps I am not setting up the raw disk correctly.

Edited by HerbertJ
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DSM SMART support is hit or miss period, more so with RDM.  Since with an RDM device the drive is technically still attached to the ESXi controller, you may be able to use ESXi to report SMART status. That works on my NVMe drives but I have never tried with LSI or other SATA controller.

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