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Xen hangs on "Starting QEMU as disk backend for dom0"

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All,

 

I upgraded my unraid server earlier today with a i7 chip that can use vt-d, whereas the prior i3 could not.  Booting into standard non-xen unraid works fine, no issues.  However, even since I enabled vt-d in BIOS, when I try to boot into Xen, and Xen safemode I end up hanging on "Starting QEMU as disk backend for dom0".  It seems to just sit there and sit there.

 

Am I missing something?

 

The machine does now have an i7 and 32GB of memory.

 

Thanks,

Marcus

I suggested this in the beta4 thread, but it's likely better to keep this conversation in a dedicated thread as it likely has nothing to do with b4 specifically.

 

Have you tried to update your BIOS? Maybe there is something funky in the current version/settings.

  • Author

I suggested this in the beta4 thread, but it's likely better to keep this conversation in a dedicated thread as it likely has nothing to do with b4 specifically.

 

Have you tried to update your BIOS? Maybe there is something funky in the current version/settings.

 

Yeah, so doing that I got it started once, started my VM, had to destroy the VM because I got a passthrough device wrong, as it did not work.  At that point, I lost my display, and the network went down.  On the reboot it's back to hanging on "Starting QEMU as disk backend for dom0".

 

It should not be bad settings inside unraid, right?  I mean all I have there is the syslinux folder and the config folder, and they are stock.

I suggested this in the beta4 thread, but it's likely better to keep this conversation in a dedicated thread as it likely has nothing to do with b4 specifically.

 

Have you tried to update your BIOS? Maybe there is something funky in the current version/settings.

 

Yeah, so doing that I got it started once, started my VM, had to destroy the VM because I got a passthrough device wrong, as it did not work.  At that point, I lost my display, and the network went down.  On the reboot it's back to hanging on "Starting QEMU as disk backend for dom0".

 

It should not be bad settings inside unraid, right?  I mean all I have there is the syslinux folder and the config folder, and they are stock.

 

I didn't follow my own advice and keep the conversation here. :)

 

I would be surprised if it's UnRAID. Assuming you are trying on Beta4, you could try the same on Beta3 and see if it behaves differently. Otherwise I only have the suggestions I listed in the beta thread (reset bios settings, and test ram).

 

  • Author

I suggested this in the beta4 thread, but it's likely better to keep this conversation in a dedicated thread as it likely has nothing to do with b4 specifically.

 

Have you tried to update your BIOS? Maybe there is something funky in the current version/settings.

 

Yeah, so doing that I got it started once, started my VM, had to destroy the VM because I got a passthrough device wrong, as it did not work.  At that point, I lost my display, and the network went down.  On the reboot it's back to hanging on "Starting QEMU as disk backend for dom0".

 

It should not be bad settings inside unraid, right?  I mean all I have there is the syslinux folder and the config folder, and they are stock.

 

I didn't follow my own advice and keep the conversation here. :)

 

I would be surprised if it's UnRAID. Assuming you are trying on Beta4, you could try the same on Beta3 and see if it behaves differently. Otherwise I only have the suggestions I listed in the beta thread (reset bios settings, and test ram).

 

I'll try RAM next, need to get food right now.

 

In BIOS there are two virtualization settings, one is VT-d, and there is a second, both of these should be enabled right?  I'll get specifically what they are named after I get some food. 

 

I'm starting to wonder if it is the board.  I know the CPU is good, as the machine it came from had no issues with Xen Server or ESXi.  Sadly the board it was in does not have enough SATA boards to check with this configuration. 

 

thanks!

I suggested this in the beta4 thread, but it's likely better to keep this conversation in a dedicated thread as it likely has nothing to do with b4 specifically.

 

Have you tried to update your BIOS? Maybe there is something funky in the current version/settings.

 

Yeah, so doing that I got it started once, started my VM, had to destroy the VM because I got a passthrough device wrong, as it did not work.  At that point, I lost my display, and the network went down.  On the reboot it's back to hanging on "Starting QEMU as disk backend for dom0".

 

It should not be bad settings inside unraid, right?  I mean all I have there is the syslinux folder and the config folder, and they are stock.

 

I didn't follow my own advice and keep the conversation here. :)

 

I would be surprised if it's UnRAID. Assuming you are trying on Beta4, you could try the same on Beta3 and see if it behaves differently. Otherwise I only have the suggestions I listed in the beta thread (reset bios settings, and test ram).

 

I'll try RAM next, need to get food right now.

 

In BIOS there are two virtualization settings, one is VT-d, and there is a second, both of these should be enabled right?  I'll get specifically what they are named after I get some food. 

 

I'm starting to wonder if it is the board.  I know the CPU is good, as the machine it came from had no issues with Xen Server or ESXi.  Sadly the board it was in does not have enough SATA boards to check with this configuration. 

 

thanks!

 

There is VT-x and VT-d. VT-x is basic hardware virtualization enabled, and VT-d enables pass-through. Actually as I write this I am thinking you should be able to boot into Xen config even with VT-d disabled - it just means you won't have passthrough (but would be good to see if you can boot properly).

 

I am pretty sure the MB should work for this (unlike ASUS, ASrock is good with VT-d support). I have a Z87 Extreme6 MB with passthrough working (this is a XenServer, not UnRAID), and I've seen other posters with ASrock MBs having good success.

 

I'd try and boot into Xen without VT-d and try and start a VM (again this should work - just no passthrough). Then test the memory depending on results.

 

  • Author

There is VT-x and VT-d. VT-x is basic hardware virtualization enabled, and VT-d enables pass-through. Actually as I write this I am thinking you should be able to boot into Xen config even with VT-d disabled - it just means you won't have passthrough (but would be good to see if you can boot properly).

 

I am pretty sure the MB should work for this (unlike ASUS, ASrock is good with VT-d support). I have a Z87 Extreme6 MB with passthrough working (this is a XenServer, not UnRAID), and I've seen other posters with ASrock MBs having good success.

 

I'd try and boot into Xen without VT-d and try and start a VM (again this should work - just no passthrough). Then test the memory depending on results.

 

That's the thing, the minute I disable VT-d I can boot into Xen, just with no pass-through.  The BIOS on the board shows as vt-d as being available so I know both the board and the cpu support it. 

 

Let me test the memory.

 

Thanks!

  • Author

There is VT-x and VT-d. VT-x is basic hardware virtualization enabled, and VT-d enables pass-through. Actually as I write this I am thinking you should be able to boot into Xen config even with VT-d disabled - it just means you won't have passthrough (but would be good to see if you can boot properly).

 

I am pretty sure the MB should work for this (unlike ASUS, ASrock is good with VT-d support). I have a Z87 Extreme6 MB with passthrough working (this is a XenServer, not UnRAID), and I've seen other posters with ASrock MBs having good success.

 

I'd try and boot into Xen without VT-d and try and start a VM (again this should work - just no passthrough). Then test the memory depending on results.

 

That's the thing, the minute I disable VT-d I can boot into Xen, just with no pass-through.  The BIOS on the board shows as vt-d as being available so I know both the board and the cpu support it. 

 

Let me test the memory.

 

Thanks!

 

I went ahead and disabled vt-d in BIOS/UEFI, and Unraid/Xen booted fine.  I was able to startup my Windows VM with no issues.  That pretty much rules out the memory and disk right?

 

I mean the only thing left then is either the board, or something related to xen and vt-d......?

 

BIOS is at the latest now.

 

-Marcus

I'd put my money on the vt-d implementation on that particular model board. I'd do a bit of a Google search to see if others have had problems with that board.

 

Sent from my Nexus 4 using Tapatalk

 

 

  • Author

I'd put my money on the vt-d implementation on that particular model board. I'd do a bit of a Google search to see if others have had problems with that board.

 

Sent from my Nexus 4 using Tapatalk

 

This is so weird...

 

 

First boot, with vt-d on, froze at:

 

Triggering udev events:  /sbin/udevadm trigger --action=change

 

Powercycled, with vt-d on, froze at:

 

starting appletalk daemons:  cnid_metad afpd

 

Powercycled, with vt-d on, froze at:

 

Starting Xen commons:  /etc/rc.d/rc.xencommons

 

It's stopping earlier and earlier, let me see about logs.....

 

-Marcus

  • Author

Here is a log of it booting correctly with vt-d disabled.  I need to see if the powerdown scripts will actually log and save logs to \boot\logs\ if it is shutdown unclean.

 

http://tny.cz/dcecaca5

 

Thanks!

  • Author

The Powerdown script doesn't copy logs to /boot/logs until the host shuts down, so there is no way I'm going to get the startup logs..... hmmmm

 

Any thoughts?  Contemplating running to Microcenter and just grabbing a new board.

 

Thanks!

 

  • Author

Tried a different thumbdrive, with a fresh install of beta 4....

 

It hangs at Starting QEMU as well.  Would love to know if the issue is my processor or the board. 

 

Ugh.

 

 

Tried a different thumbdrive, with a fresh install of beta 4....

 

It hangs at Starting QEMU as well.  Would love to know if the issue is my processor or the board. 

 

Ugh.

 

Currently I have the following on the way for a new build that will use xen.

 

http://www.newegg.com/Product/Product.aspx?Item=N82E16813157371

http://www.newegg.com/Product/Product.aspx?Item=N82E16819116896

 

If this thread is still going I will post an update or if not I will PM you.  I know they are not exact but it will at least knock out Asrock's implementation of vt-d.

Tried a different thumbdrive, with a fresh install of beta 4....

 

It hangs at Starting QEMU as well.  Would love to know if the issue is my processor or the board. 

 

Ugh.

 

This doesn't surprise me as if the USB was bad, you'd likely have had issues on any boot - not just Xen.

 

If you were able to do passthrough on the CPU on a different board via ESX (which I think you mentioned), then the board is a likely guess. You could always try putting the CPU back in your other board with a clean UnRAID install (since you mentioned it doesn't have enough SATA ports to support your array. If Xen works, you know it's your board.  If not, then maybe something has gone screwy with your CPU (though this is less likely since they don't really have pins to get bent or anything anymore).

 

Or just pick up another board to test. It all depends on the return policy at your local store - I know most suck with CPUs, but are not bad with motherboards.

 

Tried a different thumbdrive, with a fresh install of beta 4....

 

It hangs at Starting QEMU as well.  Would love to know if the issue is my processor or the board. 

 

Ugh.

 

Currently I have the following on the way for a new build that will use xen.

 

http://www.newegg.com/Product/Product.aspx?Item=N82E16813157371

http://www.newegg.com/Product/Product.aspx?Item=N82E16819116896

 

If this thread is still going I will post an update or if not I will PM you.  I know they are not exact but it will at least knock out Asrock's implementation of vt-d.

 

Not true because implementation of of vt-d can even be bios dependent let alone across models of motherboards of a vendor. Unless you find confirmed reports of a particular model motherboard on a specific version of bios working with vt-d for xen then you cannot be sure.

 

Sent from my Nexus 4 using Tapatalk

 

 

Tried a different thumbdrive, with a fresh install of beta 4....

 

It hangs at Starting QEMU as well.  Would love to know if the issue is my processor or the board. 

 

Ugh.

 

Currently I have the following on the way for a new build that will use xen.

 

http://www.newegg.com/Product/Product.aspx?Item=N82E16813157371

http://www.newegg.com/Product/Product.aspx?Item=N82E16819116896

 

If this thread is still going I will post an update or if not I will PM you.  I know they are not exact but it will at least knock out Asrock's implementation of vt-d.

 

Not true because implementation of of vt-d can even be bios dependent let alone across models of motherboards of a vendor. Unless you find confirmed reports of a particular model motherboard on a specific version of bios working with vt-d for xen then you cannot be sure.

 

Sent from my Nexus 4 using Tapatalk

 

I agree but what I was saying that is if it fails we will know more.

All,

 

I upgraded my unraid server earlier today with a i7 chip that can use vt-d, whereas the prior i3 could not.  Booting into standard non-xen unraid works fine, no issues.  However, even since I enabled vt-d in BIOS, when I try to boot into Xen, and Xen safemode I end up hanging on "Starting QEMU as disk backend for dom0".  It seems to just sit there and sit there.

 

Am I missing something?

 

The machine does now have an i7 and 32GB of memory.

 

Thanks,

Marcus

 

Hi, I just had this exact problem. Here's how I solved it:

- I renamed all my plugins to *.old

- moved the Xen VM's to /mnt/cache/domains/

- updated "arch.cfg" paths

-rebooted into safe mode, shutdown from there and rebooted again.

 

I had exactly the same symptoms as you and it would appear that unRaid6-Beta4 looked like it was getting stuck on "Starting QEMU as disk backend for dom0" when in fact it was trying to sort out quite unrelated commands - from the plg's mainly.

 

Hope it helps.

  • Author

I got frustrated, went out and bought a Asrock Z87 Extreme 6 board, and a I7-4770s processor.  It's running fine now.  I'm going to take the old 3770 and Z77 Extreme 4 board and just make another lab pc =)

 

 

-Marcus

  • Author

All,

 

I upgraded my unraid server earlier today with a i7 chip that can use vt-d, whereas the prior i3 could not.  Booting into standard non-xen unraid works fine, no issues.  However, even since I enabled vt-d in BIOS, when I try to boot into Xen, and Xen safemode I end up hanging on "Starting QEMU as disk backend for dom0".  It seems to just sit there and sit there.

 

Am I missing something?

 

The machine does now have an i7 and 32GB of memory.

 

Thanks,

Marcus

 

Hi, I just had this exact problem. Here's how I solved it:

- I renamed all my plugins to *.old

- moved the Xen VM's to /mnt/cache/domains/

- updated "arch.cfg" paths

-rebooted into safe mode, shutdown from there and rebooted again.

 

I had exactly the same symptoms as you and it would appear that unRaid6-Beta4 looked like it was getting stuck on "Starting QEMU as disk backend for dom0" when in fact it was trying to sort out quite unrelated commands - from the plg's mainly.

 

Hope it helps.

 

So with the new board and processor it boots into Xen fine now with vt-d enabled.  However, if I run a grep against DMESG to look for IOMMU I do not see it enabled?

 

-Marcus

  • Author

All,

 

I upgraded my unraid server earlier today with a i7 chip that can use vt-d, whereas the prior i3 could not.  Booting into standard non-xen unraid works fine, no issues.  However, even since I enabled vt-d in BIOS, when I try to boot into Xen, and Xen safemode I end up hanging on "Starting QEMU as disk backend for dom0".  It seems to just sit there and sit there.

 

Am I missing something?

 

The machine does now have an i7 and 32GB of memory.

 

Thanks,

Marcus

 

Hi, I just had this exact problem. Here's how I solved it:

- I renamed all my plugins to *.old

- moved the Xen VM's to /mnt/cache/domains/

- updated "arch.cfg" paths

-rebooted into safe mode, shutdown from there and rebooted again.

 

I had exactly the same symptoms as you and it would appear that unRaid6-Beta4 looked like it was getting stuck on "Starting QEMU as disk backend for dom0" when in fact it was trying to sort out quite unrelated commands - from the plg's mainly.

 

Hope it helps.

 

So with the new board and processor it boots into Xen fine now with vt-d enabled.  However, if I run a grep against DMESG to look for IOMMU I do not see it enabled?

 

-Marcus

 

Nevermind, I realize it won't show it since I'm in Dom0.  I believe where I saw it previously was when booting directly into unraid without Xen, where it would make sense to be displayed.

 

thanks!

 

Now if I could just get passthrough video working.

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