I think I found the best way to do software RAID with Windows

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lizardking009

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Nov 18, 2005
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Windows on Proxmox VE, that is. I loaded Proxmox on an SSD and Windows on another drive in a qcow2 image file. I built a 4 drive RAID 6 array with mdadm and attached /dev/md0 to the Windows VM. The LUN passed through with no problems and I could format it as NTFS.

I copied about 500gb of ISOs to it and averaged a little above 60mb/second which isn't terrible since those are Green drives on RAID 6. Smartctl also worked to enable TLER.

So here's another option for Windows users who want cheap, effective software RAID. Proxmox is pretty easy to use itself and the software RAID stuff is easy to figure out for a a Linux newbie.
 
Thats interesting setup there. Never heard of Proxmox.

TBH it seems like a lot of work with not a lot in return.
 
Proxmox is a free linux distro with a pretty nice web front end for KVM - took maybe 10 minutes to load. It doesn't take much longer than an install of ESXi. Windows load time is similar to native. It took maybe an hour to set up, including Windows patching, but not including the hardware build time or the RAID build time.

The return is cheap, fast, reliable software RAID with the compatibility of Windows. It would have taken me a lot longer to set up Samba properly and the solution is faster than my SW RAID iSCSI target plus Windows VM on vSphere.
 
So can you actually run windows normally like you would on a desktop?
 
Provided that what you want to do will run in a VM, that is. As I recall some (most? all?) VMs don't offer direct access to hardware like USB and audio devices. That and video performance takes a serious hit. But for server tasks, ones that don't require the absolute total performance of the box, it's an interesting way to get things set up.
 
That and video performance takes a serious hit.
Click to expand...

Even with accelerated drivers video performance is much lower than native. Disk performance is also significantly lower than native but can be helped with a raid.

I know this because I have been trying to get a working solution that allows me to do my 3D image research in 64 bit windows under a 64 bit linux based host for the last 3 years. Even with a 3.0 GHz i7 and 4 cores allocated to the guest I get no where near the performance of native. Heck I do not get the performance of a athlon X2 from 3 to 5 years ago in my guest. This is with vmware player, vmware server, xen, kvm, virtualbox or vmware esxi. All configured to use the CPU's virtulization support.
 
drescherjm said:
Even with a 3.0 GHz i7 and 4 cores allocated to the guest I get no where near the performance of native.
Click to expand...

remember that there are 4 physical cores and 4 logical, and the logical core is about equivalent to 35% of a physical core. given that you cant select which of the 4 cores get allocated (let alone even easily tell which cores are real and which are imaginary, and the fact that the core designation numbers change from boot to boot...) its possible that the cores that the VM is using is any number of physical cores between 0 and 4. its possible for it to be assigned all of the 4 logical and no physical cores, bringing a large performance hit.
 
It's not as much a cpu performance problem but more of everything but the cpu runs considerably slower in a VM.

KVM has the fastest disk but slow video. VB has faster video (not like you could play starcraft 2 in it but its acceptable for my 3D Lung and Breast CT images) but very slow disk with loads of kernel time during io. vmware server is slow at everything. Vmware esxi has no accelerated video and does not let you use the gpu for a guest (as far as I can see) so all video is through the network.
 
I have both AMD & Intel platforms that support hardware passthrough. Going to set this up in the next month and let you guys know how/if it works.

I have a Q45 board with Q6600 on intel and an 890FX with Phenom 1090T on amd.

KVM w/ virt-manager on ubutnu 10.04 lets you do this as does Xen.

You should simply load native drivers in windows for the devices and all i/o calls are native. The only overhead I think is the i/o address re-mapping (someone correct me if I'm wrong).
 
lizardking009 said:
Windows on Proxmox VE, that is. I loaded Proxmox on an SSD and Windows on another drive in a qcow2 image file. I built a 4 drive RAID 6 array with mdadm and attached /dev/md0 to the Windows VM. The LUN passed through with no problems and I could format it as NTFS.

I copied about 500gb of ISOs to it and averaged a little above 60mb/second which isn't terrible since those are Green drives on RAID 6. Smartctl also worked to enable TLER.

So here's another option for Windows users who want cheap, effective software RAID. Proxmox is pretty easy to use itself and the software RAID stuff is easy to figure out for a a Linux newbie.
Click to expand...

How did you format in NTFS to take advantage of the under-lying chunk size & number of disks in the array? Windows is going to be ignorant about that.
 
Robstar said:
How did you format in NTFS to take advantage of the under-lying chunk size & number of disks in the array? Windows is going to be ignorant about that.
Click to expand...

When you are installing windows, instead of clicking on install, choose repair (vista & 7). then open the command line and you can format NTFS using the diskparted tool

Select Disk X
Create Partition Primary
Format FS=NTFS Label="label" unit=4096 nowait

Then go back and install windows to the partitions you just created.
 
Robstar said:
How did you format in NTFS to take advantage of the under-lying chunk size & number of disks in the array? Windows is going to be ignorant about that.
Click to expand...

You can do it, but there really isn't any reason to unless your software vendor has specific requirements. Partition alignment is important but 2008+ start partitions at the 1mb mark so no concerns there.
 
I think he was referring to alignment with stripe size, which still would affect performance, albeit minimally.
 
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