Maximum disk size that can be passed through to Unraid Guest

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Maximum disk size that can be passed through to Unraid Guest

Postby Simt » 14. Mar 2020, 16:07

Hi all,
I'm getting a warning when I start up my Guest about a large 10Tb physical disk I've attached to SATA storage in a Vbox guest.
Warning message is:

The medium '/home/home/VirtualBox VMs/unraid_home/First_10TB.vmdk' has a logical size of 9TB but the file system the medium is located on can only handle files up to 7TB in theory.
We strongly recommend to put all your virtual disk images and the snapshot folder onto a proper file system (e.g. ext3) with a sufficient size.

Error ID: FatPartitionDetected
Severity: Warning


I've been able to get Unraid running as a guest on top of a Ubuntu 18.4 host. This is a 10TB disk that had already been formatted by a bare metal host Unraid earlier with a single XFS partition. I'm pointing to the raw disk with a VMDK file.

The disk status in Unraid is:
VBOX_HARDDISK_VBf91b0b21-d343ebca - 10 TB (sdc)
Name: Disk 1
Partition size: 9,766,436,764 KB (K=1024)
Partition format: unknown
File system status: Unmountable: Unsupported partition layout
File system type: auto
(greyed out)

Any ideas on how I could fix this inside VirtualBox? (Or Unraid for that matter.)

'regards,
Simt
Simt
 
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Re: Maximum disk size that can be passed through to Unraid Guest

Postby mpack » 14. Mar 2020, 16:10

The message seems straightforward? If correct then you can't fix it in the guest, it's reporting a problem on the host, i.e. the drive which is hosting the VDI.

Is it correct? The host is using a FAT formatted partition to host a VMDK? Or if not FAT, what is the actual maximum size of a file on that host partition (min(partition_size,filesystem_max_file_size)).
mpack
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Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Mostly XP

Re: Maximum disk size that can be passed through to Unraid Guest

Postby Simt » 14. Mar 2020, 16:43

mpack wrote:The message seems straightforward? If correct then you can't fix it in the guest, it's reporting a problem on the host, i.e. the drive which is hosting the VDI.

Is it correct? The host is using a FAT formatted partition to host a VMDK? Or if not FAT, what is the actual maximum size of a file on that host partition (min(partition_size,filesystem_max_file_size)).


Hi, I'm new to all of this, and trying to make sense of what you're asking. I wouldn't have thought the host is using a FAT formatted partition to host a vmdk. I actually wouldn't have though it was hosting it at all. There's no VDI in use for this. (Well actually there is one VHD which is VFAT and contains all 177MB of the Unraid OS.) I thought the VMDK was telling the guest where to find the raw disk for direct access. No hosting involved??

I've attached the VMDK as a txt file if that's of any use.
Attachments
First_10TB.vmdk.txt
(540 Bytes) Downloaded 1 time
Simt
 
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Re: Maximum disk size that can be passed through to Unraid Guest

Postby mpack » 14. Mar 2020, 18:50

Some basic terminology: the physical PC that you run VMs on is referred to as "the host". The VM can also be called "the guest". So every part of a VM is hosted, i.e. uses physical PC resources. In particular, yes disk space is provided by the host so your VDI/VMDK is hosted.

Forget my mention of VDI, I lazily failed to check, and simply assumed you would be using native VirtualBox VDI format instead of the foreign VMDK format. Which you should be.

And no, the first few bytes of your VMDK is not useful to me. As already mentioned the error message concerns the host partition, not any part of the VM. More useful would be to provide a VM log file. With the VM fully shut down, right click it in the GUI. Select "Show Log" and save "VBox.log" (no other file) to a zip file. Attach the zip here.
mpack
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Posts: 31470
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Primary OS: MS Windows 10
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Re: Maximum disk size that can be passed through to Unraid Guest

Postby Simt » 17. Mar 2020, 15:24

mpack wrote:And no, the first few bytes of your VMDK is not useful to me. As already mentioned the error message concerns the host partition, not any part of the VM. More useful would be to provide a VM log file. With the VM fully shut down, right click it in the GUI. Select "Show Log" and save "VBox.log" (no other file) to a zip file. Attach the zip here.


I got it working! Though I still do get the warning message :( - I also posted in the Unraid forums to see if anyone there had an idea, and someone looked at the VMDK file and spotted an inconsinstancy that proved to be the culprit.

mpack, I'm not sure if you appreciated what I said about the VMDK. I didn't share the first few kBs, that was the entire VMDK, it's a pointer to a physical disk. And it turns out I had set it up to point to '../dev/sda1' - the first partition I believe. When what I needed to do, and it worked, was to point to '..dev/sda' - the entire drive.

Happy to say, even though I get that Vbox warning, Unraid now recognises the disk properly and mounts it such that it has full access to it (all 10TB).

I've attached the Vbox logs, from before and after working. Can't say i see much difference though. Also pics of what Unraid saw before and after fixing the pointer.

Not Recognised
unraid_NOT_recognised.png
unraid_NOT_recognised.png (51.37 KiB) Viewed 105 times


Recognised (Yay!)
disk_recognised.png
disk_recognised.png (49.54 KiB) Viewed 105 times


-simt
Attachments
Vbox_logs.zip
(53.09 KiB) Downloaded 1 time
Simt
 
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