This guest has ~ 63 MB free on its disk, which is very tight.

We make many changes to the guest which involve writing.  In this
guest we upload about 13.5 MB of drivers, plus RHEV-APT, and we make
changes to the Windows Registry (which increase its size).

So I can see that we are clearly on the edge.  A small change to
virtio-win seems to have pushed it over.

A guest ought to have a bit more free space before conversion.  Was this
guest specially designed as part of a test to have low free space?

Previously (RHBZ#1139543) we had problems with guests with not enough free
space to complete a conversion, and we now check that there's at least
20M or 50M free (depending on the guest).  This may not be sufficient for
Windows guests.

Hi Richard,

   You're right, the problem is really caused by not having enough space in original windows guest, but I don't understand why v2v can convert the same guest on rhel8 fast stream with virtio-win-1.9.16-2.

   As v2v will copy more file from virtio-win-1.9.16-2 to windows guest during conversion, I think v2v should improve the Minimum free space for windows in v2v man page. v2v man page said Minimum free space：20 MB for Windows "C:" drive, which I think is too small for windows guest.

   Besides, I think the v2v should improve the error message about no enough space for windows guest, v2v will report below correct error when convert a linux guest which has no enough space left(fixed in bug1139543)

    # virt-v2v -ic vpx://root.73.141/data/10.73.196.89/?no_verify=1 -it vddk -io vddk-libdir=/home/vddk6.7 -io vddk-
thumbprint=1F:97:34:5F:B6:C2:BA:66:46:CB:1A:71:76:7D:6B:50:1E:03:00:EA  -o rhv-upload -of qcow2 -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -oo rhv-cluster=NFS -ip /home/passwd -op /home/rhvpasswd  -os nfs_data -n ovirtmgmt  Auto-esx6.5-rhel7.6-no-space -oo rhv-direct=true
[   0.6] Opening the source -i libvirt -ic vpx://root.73.141/data/10.73.196.89/?no_verify=1 Auto-esx6.5-rhel7.6-no-space -it vddk  -io vddk-libdir=/home/vddk6.7 -io vddk-thumbprint=1F:97:34:5F:B6:C2:BA:66:46:CB:1A:71:76:7D:6B:50:1E:03:00:EA
[   2.2] Creating an overlay to protect the source from being modified
[   5.6] Opening the overlay
[  12.9] Inspecting the overlay
[  34.3] Checking for sufficient free disk space in the guest
virt-v2v: error: not enough free space for conversion on filesystem 
‘/’.  4784128 bytes free < 20000000 bytes needed

If reporting bugs, run virt-v2v with debugging enabled and include the 
complete output:

  virt-v2v -v -x [...]



Below is the steps to reproduce the bug this time:

1.Prepare a VMware windows guest which has about 60MB left in C:\, pls check screenshot"windows-guest-60MB-left.png"

2.Use v2v convert the guest from VMware to rhv on rhel8 slow train, version of virtio-win is 1.9.16-2 

2.1 # rpm -q virt-v2v libguestfs virtio-win
virt-v2v-1.40.2-27.module+el8.4.0+9282+0bdec052.x86_64
libguestfs-1.40.2-27.module+el8.4.0+9282+0bdec052.x86_64
virtio-win-1.9.16-2.el8.noarch
 
2.2 # virt-v2v -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 -o rhv-upload -of raw -os nfs_data -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -op /home/rhvpasswd -oo rhv-cluster=NFS -oa preallocated -oo rhv-direct -it vddk -io vddk-libdir=/home/vddk7.0 -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78 -ip /home/passwd  esx7.0-win10-no-enough-space
[   0.6] Opening the source -i libvirt -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 esx7.0-win10-no-enough-space -it vddk  -io vddk-libdir=/home/vddk7.0 -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78
[   2.2] Creating an overlay to protect the source from being modified
[   3.0] Opening the overlay
[  10.0] Inspecting the overlay
[  13.3] Checking for sufficient free disk space in the guest
[  13.3] Estimating space required on target for each disk
[  13.3] Converting Windows 10 Enterprise to run on KVM
virt-v2v: warning: /usr/share/virt-tools/pnp_wait.exe is missing.  
Firstboot scripts may conflict with PnP.
virt-v2v: error: /usr/share/virtio-win/virtio-win.iso: cannot open 
virtio-win ISO file: internal_write: write: No space left on device

If reporting bugs, run virt-v2v with debugging enabled and include the 
complete output:

  virt-v2v -v -x [...]

2.3 Downgrade virtio-win to 1.9.15-0, then v2v can convert the guest successfully
#  virt-v2v -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 -o rhv-upload -of raw -os nfs_data -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -op /home/rhvpasswd -oo rhv-cluster=NFS -oa preallocated -oo rhv-direct -it vddk -io vddk-libdir=/home/vddk7.0 -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78 -ip /home/passwd  esx7.0-win10-no-enough-space
[   0.6] Opening the source -i libvirt -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 esx7.0-win10-no-enough-space -it vddk  -io vddk-libdir=/home/vddk7.0 -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78
[   2.3] Creating an overlay to protect the source from being modified
[   3.2] Opening the overlay
[  10.4] Inspecting the overlay
[  14.0] Checking for sufficient free disk space in the guest
[  14.0] Estimating space required on target for each disk
[  14.0] Converting Windows 10 Enterprise to run on KVM
virt-v2v: warning: /usr/share/virt-tools/pnp_wait.exe is missing.  
Firstboot scripts may conflict with PnP.
virt-v2v: warning: there is no QXL driver for this version of Windows (10.0 
x86_64).  virt-v2v looks for this driver in 
/usr/share/virtio-win/virtio-win.iso

The guest will be configured to use a basic VGA display driver.
virt-v2v: This guest has virtio drivers installed.
[  22.4] Mapping filesystem data to avoid copying unused and blank areas
[  22.9] Closing the overlay
[  23.1] Assigning disks to buses
[  23.1] Checking if the guest needs BIOS or UEFI to boot
[  23.1] Initializing the target -o rhv-upload -oa preallocated -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -op /home/rhvpasswd -os nfs_data
[  24.5] Copying disk 1/1 to qemu URI json:{ "file.driver": "nbd", "file.path": "/var/tmp/rhvupload.DCdbb5/nbdkit0.sock", "file.export": "/" } (raw)
^C  (0.00/100%)


3.Use v2v convert the guest from VMware to rhv on rhel8 fast train, version of virtio-win is 1.9.16-2, but v2v can convert the same guest successfully

3.1 # rpm -q virt-v2v libguestfs virtio-win
virt-v2v-1.42.0-9.module+el8.4.0+9561+069bb9c1.x86_64
libguestfs-1.44.0-2.module+el8.4.0+10146+75917d2f.x86_64
virtio-win-1.9.16-2.el8.noarch

3.2 # virt-v2v -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 -o rhv-upload -of raw -os nfs_data -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -op /home/rhvpasswd -oo rhv-cluster=NFS -oa preallocated -oo rhv-direct -it vddk -io vddk-libdir=/home/vddk7.0 -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78 -ip /home/passwd  esx7.0-win10-no-enough-space
[   0.6] Opening the source -i libvirt -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 esx7.0-win10-no-enough-space -it vddk  -io vddk-libdir=/home/vddk7.0 -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78
[   2.2] Creating an overlay to protect the source from being modified
[   3.0] Opening the overlay
[   7.5] Inspecting the overlay
[  11.4] Checking for sufficient free disk space in the guest
[  11.4] Estimating space required on target for each disk
[  11.4] Converting Windows 10 Enterprise to run on KVM
virt-v2v: warning: /usr/share/virt-tools/pnp_wait.exe is missing.  
Firstboot scripts may conflict with PnP.

** (process:2282640): WARNING **: 21:58:08.570: Entity http://pcisig.com/pci/1B36/0100 referenced but not defined
virt-v2v: warning: there is no QXL driver for this version of Windows (10.0 
x86_64).  virt-v2v looks for this driver in 
/usr/share/virtio-win/virtio-win.iso

The guest will be configured to use a basic VGA display driver.
virt-v2v: This guest has virtio drivers installed.
[  18.0] Mapping filesystem data to avoid copying unused and blank areas
[  18.5] Closing the overlay
[  18.7] Assigning disks to buses
[  18.7] Checking if the guest needs BIOS or UEFI to boot
[  18.7] Initializing the target -o rhv-upload -oa preallocated -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -op /home/rhvpasswd -os nfs_data
[  20.1] Copying disk 1/1 to qemu URI json:{ "file.driver": "nbd", "file.path": "/tmp/v2vnbdkit.RTFH0H/nbdkit4.sock", "file.export": "/" } (raw)
^C  (0.00/100%)

Created attachment 1772194 [details]
windows-guest-60MB-left.png

> 2.3 Downgrade virtio-win to 1.9.15-0, then v2v can convert the guest successfully

I think the difference is the QXL driver.  Adding the QXL driver
seems to push us over the limit.

> I don't understand why v2v can convert the same guest on rhel8 fast stream with
> virtio-win-1.9.16-2

I'm not clear on what the difference is.  But we are very close to
the limit of free space in these tests, so it could make a difference.

> v2v man page said Minimum free space：20 MB for Windows "C:" drive, which I think
> is too small for windows guest.

Yes, I agree.  I believe this is the real bug - we should document and
check a larger limit than now.  I suggest 100 MB would be a good limit.

> Besides, I think the v2v should improve the error message about no enough space
> for windows guest

I'll see what I can do ...

I don't think this bug needs to be a blocker for RHEL 8.4.

This is the fix; it increases the required space to 100 MB
and improves the error message:

https://github.com/libguestfs/virt-v2v/commit/dfcf60c916a986a352938b432231a36558a3bc05

However I think we should put this in RHEL AV only at this time.

Verify the bug with builds:
virt-v2v-1.42.0-12.module+el8.5.0+10976+d40a93e9.x86_64

Steps:
1.Check the man page about minimum free space:
# man virt-v2v 
       Windows "C:" drive
           Minimum free space: 100 MB

           We may have to copy in many virtio drivers and guest agents.

2.Prepare a windows guest in Vmware which has 100M free in C:/, guest's detail pls see screenshot windows-100M
# virt-v2v -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 -o rhv-upload -of raw -os nfs_data -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -op /home/rhvpasswd -oo rhv-cluster=NFS -oa preallocated -oo rhv-direct -it vddk -io vddk-libdir=/home/vddk7.0/vmware-vix-disklib-distrib -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78 -ip /home/passwd  esx7.0-win10-no-enough-space
[   0.5] Opening the source -i libvirt -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 esx7.0-win10-no-enough-space -it vddk  -io vddk-libdir=/home/vddk7.0/vmware-vix-disklib-distrib -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78
[   2.2] Creating an overlay to protect the source from being modified
[   3.0] Opening the overlay
[   8.3] Inspecting the overlay
[  13.4] Checking for sufficient free disk space in the guest
[  13.4] Estimating space required on target for each disk
[  13.4] Converting Windows 10 Enterprise to run on KVM

** (process:348293): WARNING **: 10:49:50.737: Entity http://pcisig.com/pci/1B36/0100 referenced but not defined
virt-v2v: This guest has virtio drivers installed.
[  21.1] Mapping filesystem data to avoid copying unused and blank areas
[  21.5] Closing the overlay
[  21.8] Assigning disks to buses
[  21.8] Checking if the guest needs BIOS or UEFI to boot
[  21.8] Initializing the target -o rhv-upload -oa preallocated -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -op /home/rhvpasswd -os nfs_data
[  23.1] Copying disk 1/1 to qemu URI json:{ "file.driver": "nbd", "file.path": "/tmp/v2vnbdkit.QnLBEt/nbdkit4.sock", "file.export": "/" } (raw)
    (100.00/100%)
[ 681.0] Creating output metadata
[ 683.4] Finishing off

3.Prepare a windows guest which has 50M free in C:/
#  virt-v2v -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 -o rhv-upload -of raw -os nfs_data -oc https://hp-dl360eg8-03.lab.eng.pek2.redhat.com/ovirt-engine/api -op /home/rhvpasswd -oo rhv-cluster=NFS -oa preallocated -oo rhv-direct -it vddk -io vddk-libdir=/home/vddk7.0/vmware-vix-disklib-distrib -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78 -ip /home/passwd  esx7.0-win10-no-enough-space
[   0.6] Opening the source -i libvirt -ic vpx://root.198.169/data/10.73.199.217/?no_verify=1 esx7.0-win10-no-enough-space -it vddk  -io vddk-libdir=/home/vddk7.0/vmware-vix-disklib-distrib -io vddk-thumbprint=B5:52:1F:B4:21:09:45:24:51:32:56:F6:63:6A:93:5D:54:08:2D:78
[   2.3] Creating an overlay to protect the source from being modified
[   3.1] Opening the overlay
[   7.9] Inspecting the overlay
[  12.2] Checking for sufficient free disk space in the guest
virt-v2v: error: not enough free space for conversion on filesystem 
‘/’.  48.3 MB free < 100 MB needed

If reporting bugs, run virt-v2v with debugging enabled and include the 
complete output:

  virt-v2v -v -x [...]


Result：
1.Virt-v2v has update the minimum free space for windows guest from 60M to 100M in v2v man page
2.Virt-v2v has improve the error massage when the guest don't have enough space

So change the bug from ON_QA to VERIFIED.

Created attachment 1785009 [details]
windows guest 100M left

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (virt:av bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2021:4684