maharmstone
Mounting iso images causes all btrfs volumes being unreachable till reboot
Mounting ANY iso from ANY location (not only btrfs) causes this behavior. Volumes instantly disappear from win and i found no way of recovering access to them besides rebooting. Also, when you mount an iso from btrfs its content is still readable and completely fine even after volumes disappear. This behavior was noticed on w10 23h2 ltsc and w11 2263x.xxxx.
@ohno1052, @vlad196: what software do you use to mount .iso files on your setups?
With the help of FileTypesMan v2.00 tool I get these verbs on my setup:
F:\Downloads\filetypesman-x64> FileTypesMan /SelectedExt .iso /stabular .iso.txt
F:\Downloads\filetypesman-x64> type .iso.txt
# Name Caption Default Disabled LastModified CommandLine ProcessFilename In_SysFileAssoc RegKey Extended ProductName ProductVersion ProductDescription CompanyName RegKeyOwner
burn burn No No 07/12/2019 12:17:46 %SystemRoot%\System32\isoburn.exe "%1" C:\Windows\System32\isoburn.exe No HKEY_CLASS No Microsoft® Windows® 10.0.19041.1 (WinBui Windows Disc Image B Microsoft Corporatio NT AUTHORITY\SYSTEM
mount mount Yes No 07/12/2019 12:17:46 %SystemRoot%\Explorer.exe C:\Windows\Explorer.exe No HKEY_CLASS No Microsoft® Windows® 10.0.19041.2311 (Win Windows Explorer Microsoft Corporatio NT AUTHORITY\SYSTEM
open open No No 23/07/2024 12:48:03 "F:\Program Files (x86)\WinCDEmu\vmnt64.exe" "%1" F:\Program Files (x86)\WinCDEmu\vmnt64.exe No HKEY_CLASS No WinCDEmu 4.0 WinCDEmu mounter Sysprogs OU BUILTIN\Administrato
(I added the # Name ... line by hand to make the output more clear)
To reproduce the bug, it would help to know the exact verb / command line that is engaged on your machines.
In my case I double click an .iso file, and the Microsoft Virtual DVD-ROM with drive letter D: gets created:
C:\Windows\System32> wmic cdrom list brief
Caption Drive Manufacturer VolumeName
Microsoft Virtual DVD-ROM D: (Standard CD-ROM drives) CR0SCD2_EN
Do you do the same?
In my case I double click an
.isofile, and theMicrosoft Virtual DVD-ROMwith drive letterD:gets created:C:\Windows\System32> wmic cdrom list brief Caption Drive Manufacturer VolumeName Microsoft Virtual DVD-ROM D: (Standard CD-ROM drives) CR0SCD2_ENDo you do the same?
The same, default ISO virtual DVD-driver: My FileTypesMan output:
burn burn No No 5/7/2022 7:28:03 AM %SystemRoot%\System32\isoburn.exe "%1" C:\Windows\System32\isoburn.exe No HKEY_CLASS No
mount mount Yes No 5/7/2022 7:28:03 AM %SystemRoot%\Explorer.exe C:\Windows\Explorer.exe No HKEY_CLASS No
I noticed that btrfs volume disappears regardless of where .iso file is. That is, if I open .iso from a non-BTRFS disk (ntfs, disk C;), the BTRFS disk will still disappear (disk D:). It's not a problem with one .iso, I've tried different images for the test. I think the problem is not related to the files on the btrfs disk, it is somewhere at the level of running a virtual DVD
Do you know how to check it?
The same, default ISO virtual DVD-driver: My FileTypesMan output:
Thanks for confirmation.
I noticed that btrfs volume disappears regardless of where .iso file is. That is, if I open .iso from a non-BTRFS disk (ntfs, disk C;), the BTRFS disk will still disappear (disk D:).
OK, that doesn't happen on my w10 21H2.
It's not a problem with one .iso, I've tried different images for the test. I think the problem is not related to the files on the btrfs disk, it is somewhere at the level of running a virtual DVD
Do you know how to check it?
Not really, I am just another user.
Looks like cdrom.sys or some upper driver is to blame. On my machine cdrom.sys version is 10.0.19041.1 (WinBuild.160101.0800):
Versions could be inspected using CLI too. Just in case, I checked versions of both cdrom.sys and cdfs.sys:
Microsoft Windows [Version 10.0.19044.3086]
(c) Microsoft Corporation. All rights reserved.
C:\Users\saukrs> powershell "gwmi Win32_SystemDriver | where {$_.Name -eq 'cdrom' -or $_.Name -eq 'cdfs' -or $_.Name -eq 'btrfs' } | select Name,Caption,@{n='Version';e={(gi $_.pathname).VersionInfo.FileVersion}},Pathname"
Name Caption Version Pathname
---- ------- ------- --------
btrfs btrfs 1.9.0 C:\Windows\system32\drivers\btrfs.sys
cdfs CD/DVD File System Reader 10.0.19041.2130 (WinBuild.160101.0800) C:\Windows\system32\DRIVERS\cdfs.sys
cdrom CD-ROM Driver 10.0.19041.1 (WinBuild.160101.0800) C:\Windows\system32\drivers\cdrom.sys
(They look pretty similar to me)
Knowing earliest failing versions might help to narrow down the regression. Especially if it comes from w10 23h2 ltsc as mentioned by @ohno1052.
EDIT: Updated the command to include version of btrfs.sys too. On my machine it's 1.9.0, and I think it's latest one.
Not really, I am just another user. Then thank you for trying to help me understand what the problem is!
In my case, the driver versions are:
Name Caption Version Pathname
---- ------- ------- --------
btrfs btrfs 1.9.0 C:\Windows\system32\drivers\btrfs.sys
cdfs CD/DVD File System Reader 10.0.22621.2506 (WinBuild.160101.0800) C:\Windows\system32\DRIVERS\cdfs.sys
cdrom CD-ROM Driver 10.0.22621.1 (WinBuild.160101.0800) C:\Windows\system32\drivers\cdrom.sys
UPD I also have external DVD-rom, and when i unplug his, btrfs don't fall, when i open ISO image.
I hope this information will be useful for identifying the issue :)
I took driver versions and used the following pages to identify Windows builds reported in this issue:
- Windows Version Numbers
- Announcing Windows 10 version 23H2 Build 19046.4236 to the Release Preview Channel: What's New?
(The build of @ohno1052 is seemingly very new and missing from the first page)
Build 19041 of my drivers corresponds with Windows 10, Version 2004. But I run Windows 10, Version 21H2 myself, so the drivers seemingly came here from this earlier build.
| Name / Description | Version | Build Number | Public Release |
|---|---|---|---|
| Windows 10, Version 21H2 | 10.0 | 19044 | 2021-11-16 |
| Windows 11, Version 22H2 | 10.0 | 22621 | 2022-09-20 |
| ... | |||
| Windows 10, Version 23H2 | 10.0 | 19046.4236 | 2024-03-20 |
@vlad196, so the minimal known difference between working and affected Windows builds seems to be ~10 months.
@sskras Great table, thank you!
I would make a disclaimer that in my case, the external DVD-ROM that was connected was to blame These two key points (connected physical DVD-ROM and launching a virtual DVD) are what break btrfs.
Unfortunately, @ohno1052 has not yet joined us and has not shared additional information. For example, does he have a DVD-ROM? Perhaps I have a different case, but with a similar outcome. Perhaps.
in my case, the external DVD-ROM that was connected was to blame These two key points (connected physical DVD-ROM and launching a virtual DVD) are what break btrfs.
Please excuse me for misunderstanding part of your previous reply. And thank you for kindly reminding.
For the sake of completeness, could you plug it back and share the output of wmic cdrom list brief (to see if it's present here), please?
Please excuse me
Thank you for helping me understand the issue! 😊
For the sake of completeness, could you plug it back and share the output of
wmic cdrom list brief(to see if it's present here), please?
Sure!
Caption Drive Manufacturer VolumeName
ASUS SDRW-08D2S-U USB Device (Стандартные устройства чтения CD)
What I find the most strange is that image content remains completely fine even when btrfs where it is actually located becomes completely inaccessible
Sure, but cdrom.sys + cdfs.sys + btrfs.sys already have the "coordinates" of your iso file (opened in the kernel mode) in the context of your hard disk. This is my guess why your access continues.
(in fact, this is the only way i found to actually retrieve things from isos, for example with game repacks: mount iso, copy all its contents to another drive, reboot and voilà).
In the meantime, may I suggest you to try another ODD emulator ?
- https://wincdemu.sysprogs.org/ [*]
- https://alternativeto.net/software/imdisk-virtual-disk-driver/about/ [*]
- https://arsenalrecon.com/products/arsenal-image-mounter [*]
- https://www.gburner.com/online-help/virtual-drive.htm
- https://www.daemon-tools.cc/products/dtLite
- https://www.elby.ch/en/products/vcd.html
[*] The open source projects !
- https://wincdemu.sysprogs.org/ [*]
Note that the project is long-dead and has become buggier by the month.
(semi-offtopic about bugs in optical disk emulators)
@rautamiekka, true, WinCDEmu is not developed for 6y already. Still on my Microsoft Windows [Version 10.0.19044.3086] it works just fine. Just avoid the portable version (which has a minor bug re volume unload) – the installer version works just fine.
Also last version of ImDisk is 3y old too. But it still does fine on my PC.
I mounted 5 different ISO files (four of them have .img extensions, but I doubt it's significant) on 5 different optical disk emulators:
Microsoft Windows [Version 10.0.19044.3086]
(c) Microsoft Corporation. All rights reserved.
C:\Users\saukrs> wmic cdrom list brief
Caption Drive Manufacturer VolumeName
Microsoft Virtual DVD-ROM E: (Standard CD-ROM drives) CRMSEVL_EN
WinCDEmu drive V: (Standard CD-ROM drives) CRMSXEVL_EN
Arsenal Virtual SCSI CdRom Device H: (Standard CD-ROM drives) CR0SCD2_EN
gBurner Virtual DVD-ROM0000 D: (Standard CD-ROM drives) ReactOS
ImDisk doesn't emulate the optical drive, it works on the logical volume level, thus it's letter G: is absent here.
And my BTRFS volume stays perfectly mounted:
Now I start guessing if that has to do with my BTRFS volume staying on the system disk?
diskmgmt.msc shows no drive letter for the BTRFS volume, but that's probably a known issue.
(PS. I also fixed my previous comment about nearest working Windows build)
(TL;DR) @ohno1052, @vlad196: does your BTRFS volume reside on a system disk & if not, is that disk drive removable?
@sskras no, my disk instal like disk D for documents, movie, etc. And no, my disk not removable, plug trough SATA interface (even in UEFI turn off sata plug-and-play)
@vlad196 commented 8 hours ago:
my disk instal like disk D for documents, movie, etc. And no, my disk not removable, plug trough SATA interface
So you have two physical drives, and BTRFS volume(s) reside on the 2nd one – do I get it right? A screenshot of Disk Management window would probably help.
Alternatively you could just provide a built-in BTRFS-assigned partitions list (5) via BTRFS devices button (4) present on the Btrfs tab (3) of drive properties (2) window of any drive letter present by WinBtrfs (1), eg:
In my case it's a single partition. I guess your configuration will differ from mine and from configuration of @ohno1052.
@sskras
Here Disk Management and BTRFS-assigned partitions list:
Disk 2 (Диск 2) it's another disk with the linux system.
OK, so in both problematic cases BTRFS occupies the whole disk having no partitions.
@ohno1052, are all your BTRFS partitions aggregated into a single volume? If so, what is the data profile on that volume? This could be retrieved via button Show usage from properties page:
this is a single partition i created it with
mkfs.btrfs /dev/sdaand thenbtrfs device add /dev/sdb /mntbtrfs device add /dev/sdc /mntif this is easier to understand
Thanks. Was that done on Linux? (I would only argue about the terminology, and say the result is called not a partition, but a filesystem / a volume)
So setup of @vlad196 is simpler. I'll try to reproduce it once I get unused SATA drive.