Network Raid

[bobbybobwho]

I was thinking of having a high available cluster using 2 NAS NFS devices. Here are 2 possible scenarios, will they work?


Scenario 1

2 servers (Note proxmox will be installed on a local disk )


Virtual Machines will be on NFS Servers

Mount a NFS share on a proxmox server

Create a raw disk device and loop mount it so it appears as a local disk

Do same on second server.

Use drdb to replicate have network raid 1 between the two disks.

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I haven't actually tried the above but I do have the following working (although I assume it is a bad idea as I don't see anyone else who does this)

Scenario 2

Mount 2 NFS nas devices on my proxmox server
create two identical raw disk files for a kvm virtual machine , one on each share
loop mount then on the proxmox server as /dev/loop0, /dev/loop1
Create a software raid of the two devices
mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/loop0 /dev/loop
Install my virtual machine on /dev/md0

The performance of this seems very good if I remove NAS devices this just keeps working. When I re-add the NAS it rebuild fine so I end up with a really inexpensive network RAID system.

Can someone tell me why this is a bad idea ? And if so is the first scenario just as bad ?

 

[marotori]

Why don't you just put a disk image on each NSF volume - then install your machine in it - with software rare as if you had two hard drives?

Should work!

Rob


Sent from my iPhone using Tapatalk

 

[bobbybobwho]

Thank you for your reply,

I had tried that that and it works fine except I would like to manage this at the proxmox level instead of at the machine level. One point for all my raid instead of software raid on each of 10-15 different KVM's.

 

[udo]

I was thinking of having a high available cluster using 2 NAS NFS devices. Here are 2 possible scenarios, will they work?


Scenario 1

2 servers (Note proxmox will be installed on a local disk )


Virtual Machines will be on NFS Servers

Mount a NFS share on a proxmox server

Create a raw disk device and loop mount it so it appears as a local disk

Do same on second server.

Use drdb to replicate have network raid 1 between the two disks.

-------------------------------------------------------------------

I haven't actually tried the above but I do have the following working (although I assume it is a bad idea as I don't see anyone else who does this)

...

Hi,
I guess you will get an very poor performance:
Filesystem -> nfs -> raw-file as blockdevice -> drbd -> lvm -> vm-disk

I use drbd and must do some tricks to get an good performance (good hw-raid-controller, raid10, 10GB-Nic / DoplhinNIC).

Perhaps you should use 2 server-boxes with space for some disks - this will be much faster than nfs...

Udo