Create KVM with real LVM volume as hard disk (NOT image!)

[mickeyratt]

Dear all

I'd like to ask you, is there a way to use real LV for virtual hard disk for performance considerations?
Under Xen 4 the same Win2k3 server with paravirtualized drivers and LV highly outperforms KVM with PV drivers and RAW disk image.

The Proxmox web surface only allows disk image creation, as i see.

Thank you in advance!
(and sorry for newbie question)

 

[tom]

yes, see http://pve.proxmox.com/wiki/Storage_Model

 

[mickeyratt]

Thank You Tom for quick reply! Do you mean the:
[h=3]"LVM Groups with Local Backing"[/h]section?

I'd like to use teh following scenario:

2 additional hard disks (not those which has the Proxmox itself) with one software raid 1 for redundancy, created on this /dev/mdx device a PV/VG/LV and use that LV as virtual hard disk in KVM virtual machine.

Thank You!

 

[tom]

yes.

 

[mmenaz]

I'd say section "LVM_Groups_with_Local_Backing". The sample is with an usb pen driver, but of couse is just a matter of device name.
Maybe you'd better avoid sw raid, since is never suggested by proxmox team and even if it works you are going in a "very much less tested" territory.
Regards

 

[mir]

yes, see http://pve.proxmox.com/wiki/Storage_Model

Does this also imply lvextend and resize2fs?

 

[mickeyratt]

I'd say section "LVM_Groups_with_Local_Backing". The sample is with an usb pen driver, but of couse is just a matter of device name.
Maybe you'd better avoid sw raid, since is never suggested by proxmox team and even if it works you are going in a "very much less tested" territory.
Regards

Yes, it is working now perfectly, but the performance benefits was minimal. (Disk write: XEN (lvm): 45MB/s, KVM (RAW image file): 30MB/s, KVM (lvm): ~ 32-33MB/s)
I read a lot of posts on the net, and always praising XEN because of its best IO speed.

I know that softraid is not the best solution, we are a government environment with small budget
Unfortunately Proxmox don't support Intel's softraid solutions (implemented in BIOS) so i must use mdraid.

Thank You All!

 

[half_life]

Yes, it is working now perfectly, but the performance benefits was minimal. (Disk write: XEN (lvm): 45MB/s, KVM (RAW image file): 30MB/s, KVM (lvm): ~ 32-33MB/s)
I read a lot of posts on the net, and always praising XEN because of its best IO speed.

I know that softraid is not the best solution, we are a government environment with small budget
Unfortunately Proxmox don't support Intel's softraid solutions (implemented in BIOS) so i must use mdraid.

Thank You All!

I am also in a small "quasi government" IT shop. For my use case I found KVM to give superior performance to Xen. Proxmox is an ideal solution for HA on a budget. Spend the money on a real raid controller. It vastly improves things. I was able to build 2 servers w/16 cores+48g of ram + HPT-4320 controllers and 8 1TB drives for about $6k. With configured Raid 5 (3TB) I am getting about 170MB/s writes and 280MB/s reads. Did you use virtio devices?

 

[mickeyratt]

half_life: thank you for tips. We have an INTEL SR2520SAXSR system with Dual Xeon (8 cores sum) 16GB RAM, SAS expander with 6 disks, but unfortunately, when i activate raid mode in bios, Proxmox not found any hard disks, nor the created raid array. (LSI1064E controller) So i must use mdraid, as written in the following good article:

http://www.howtoforge.com/proxmox-2-with-software-raid

Thanks!

 

[half_life]

half_life: thank you for tips. We have an INTEL SR2520SAXSR system with Dual Xeon (8 cores sum) 16GB RAM, SAS expander with 6 disks, but unfortunately, when i activate raid mode in bios, Proxmox not found any hard disks, nor the created raid array. (LSI1064E controller) So i must use mdraid, as written in the following good article:

http://www.howtoforge.com/proxmox-2-with-software-raid

Thanks!

What is the result of lsmod |grep mpt ?

 

[mickeyratt]

root@proxmox:~# lsmod |grep mpt
mptsas 52926 6
mptscsih 36748 1 mptsas
mptbase 93999 2 mptsas,mptscsih
scsi_transport_sas 35086 1 mptsas

Thank You!