After a restore : "Boot failed: could not read the boot disk"

T

topi

Guest
Hello,

Quickly : a short experience with the restoration of a VM to another server.

I made a backup of all my VM from Proxmox 2.1 on the server 1 to an external USB disk drive. All my VM are KVM one, the format is raw, the disks are IDE and by default it use no cache.
I prepared a server 2 with Proxmox 2.2. This is absolutely not the same material as the server 1 : no RAID, no power supply redundancy ...
I took the backup from y external disk to restore them on the server 2. So far it works.

But, when I started the VMs (all) I got this annoying message : "Boot failed: could not read the boot disk" ...

After some searches and tests, I finally got a workaround from this post : http://forum.proxmox.com/threads/11330-VM-hdd-only-with-cache-write-through-possible

I had to change the default (No cache) disk option to "Write through" option. Maybe it's me that not master this topic or maybe there's something wrong. I don't have the time to search deeper about that, but maybe that could help somebody.
 
How large is the hard disk on the new server? Maybe it uses a sector size of 4K (advanced format disk)?
 
Hello,

The hard disk is 3TB and I use it though LVM Group. It is configured with sector size of 4K. However, all the disks for each VM are smaller than 2TB (12 GB, 80 GB ...).
 
The current default cache=none does not work with 4K sectors. I suggest you use cache=writeback instead.
 
Ok thank you for your help. It's working with the opition "cache=writeback". But, is that a bug or just not implemented ? I was not able to find such an information in the wiki.

Which I think is a little bit confusing is that I didn’t choose the sector size ... I just create a Physical Volume, a Volume Group, mounted it as LVM Group from the web-interface and restoring my VM inside. Note that the disk on the server 1 (from which I made the backup of the VM) has a block size of 512. Am I missing something ?
 

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