ZFS on OSX and Windows
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new day, new release
rc3
rc3
- Fix BSOD running CrystalDiskMark
- Fix userland hostid mismatching
- Change mount code to only open mountmgr once
Jorgen Lundman, maintainer of OpenZFS for Windows is working hard for a release edition
Test it and report remaining problems!
Releases · openzfsonwindows/openzfs
With the help of many users evaluating and reporting issues, OpenZFS on Windows becomes better and better with very short cycles between release candidates on the way to a release
Issues · openzfsonwindows/openzfs
openzfsonwindows openzfs · Discussions
rc5
In Windows 24H2 there seems to be some sort of partition background monitoring active that does an undo of "unknown" partition modifications. A current workaround is to use Active@disk editor (free) to modify sector 200.00 from value 45 to 15
2.3.1rc4 (usb disks) zpool import: no pool found · Issue #465 · openzfsonwindows/openzfs
With the help of many users evaluating and reporting issues, OpenZFS on Windows becomes better and better with very short cycles between release candidates on the way to a release
Issues · openzfsonwindows/openzfs
openzfsonwindows openzfs · Discussions
rc5
- Correct permissions of mount object (access_denied error with delete)
- Work on partitioning disks (incomplete)
- SecurityDescriptor work
- mountmgr would deadlock with Avast installed
- Change signal to userland to Windows API
- Additional mount/unmount changes.
- Fixed VSS blocker again
In Windows 24H2 there seems to be some sort of partition background monitoring active that does an undo of "unknown" partition modifications. A current workaround is to use Active@disk editor (free) to modify sector 200.00 from value 45 to 15
2.3.1rc4 (usb disks) zpool import: no pool found · Issue #465 · openzfsonwindows/openzfs
OpenZFS for Windows 2.3.1rc6
The best openzfs.sys on Windows ever
github.com
Only thing:
to run programs, from a ZFS pool you still need a
zfs set com.apple.mimic=ntfs poolname
The best openzfs.sys on Windows ever
Releases · openzfsonwindows/openzfs
OpenZFS on Linux and FreeBSD. Contribute to openzfsonwindows/openzfs development by creating an account on GitHub.
github.com
Only thing:
to run programs, from a ZFS pool you still need a
zfs set com.apple.mimic=ntfs poolname
As I understand it
Some apps ask for filesystem type. If not fat*, ntfs or Refs they refuse to work ex start the application from a ZFS pool. As long as Microsoft (or OSX) does not add ZFS (or btrfs) to the list of valid filesystems there is a need of an overrun option.
There is an additional ZFS property for ZFS on OSX and Windows "com.apple.mimic" (property was introduced with ZFS on OSX). Up to rc7 the default was off (=ZFS). This had the effect that some apps do not start from a ZFS pool unless you set com.apple.mimic manually to ntfs. The new behaviour on rc8 is that the default is "ntfs" unless you manually set another property for com.apple.mimic for a "it just works" behaviour.
Setting a different value for com.apple.mimic is possible but only needed in special use cases.
see also OpenZFS on OS X • View topic - com.apple.mimic settings
Some apps ask for filesystem type. If not fat*, ntfs or Refs they refuse to work ex start the application from a ZFS pool. As long as Microsoft (or OSX) does not add ZFS (or btrfs) to the list of valid filesystems there is a need of an overrun option.
There is an additional ZFS property for ZFS on OSX and Windows "com.apple.mimic" (property was introduced with ZFS on OSX). Up to rc7 the default was off (=ZFS). This had the effect that some apps do not start from a ZFS pool unless you set com.apple.mimic manually to ntfs. The new behaviour on rc8 is that the default is "ntfs" unless you manually set another property for com.apple.mimic for a "it just works" behaviour.
Setting a different value for com.apple.mimic is possible but only needed in special use cases.
see also OpenZFS on OS X • View topic - com.apple.mimic settings
Last edited:
Write an issue report how to reproduce.
In the past few weeks, most issues were already solved.
github.com
btw
First seconds of copy goes to ramcache
tried 5.4 GB iso, copied in 12s =450 MB/s
drive c: -> pool on .vhdx on same disk
no freeze at the end
not super, but ok for a software with debug code not optimized for performance.
To compare you would need ReFS (also CoW) with data checksums enabled
In the past few weeks, most issues were already solved.
openzfsonwindows/openzfs
OpenZFS on Linux and FreeBSD. Contribute to openzfsonwindows/openzfs development by creating an account on GitHub.
github.com
btw
First seconds of copy goes to ramcache
tried 5.4 GB iso, copied in 12s =450 MB/s
drive c: -> pool on .vhdx on same disk
no freeze at the end
not super, but ok for a software with debug code not optimized for performance.
To compare you would need ReFS (also CoW) with data checksums enabled
Last edited:
OpenZFS 2.3 on OSX s now a release edition, no longer a release candidate
github.com
Release zfs-macOS-2.3.0 · openzfsonosx/openzfs-fork
Upstream changelog RAIDZ Expansion (openzfs#15022): Add new devices to an existing RAIDZ pool, increasing storage capacity without downtime. Fast Dedup (openzfs#15896): A major performance upgrade...
github.com
Windows NAS considerations
I have collected some considerations for a Windows NAS, now as OpenZFS on Windows is near to a release state and Windows Storage Spaces is an often underestimated method to pool disks of different size or speed.
I have collected some considerations for a Windows NAS, now as OpenZFS on Windows is near to a release state and Windows Storage Spaces is an often underestimated method to pool disks of different size or speed.
OpenZFS on Windows 2.3.1 rc9 is available
OpenZFS on Windows has reached a "quite usable" state now with major problems of earlier release candidates fixed
Prior use, do some tests and read issues and discussions
github.com
- OpenZVOL unload BSOD fix
- Implement kernel vsnprintf instead of CRT version
- Change zed service from zed.inf to cmd service
- Change CMake to handle x64 and arm64 builds
- Produce ARM64 Windows installer.
- Finish Partition work at 128
- Also read Backup label in case Windows has destroyed Primary
- OpenZVOL should depend on Storport or it can load too soon
- Change FSType to NTFS as default
OpenZFS on Windows has reached a "quite usable" state now with major problems of earlier release candidates fixed
Prior use, do some tests and read issues and discussions
Releases · openzfsonwindows/openzfs
OpenZFS on Linux and FreeBSD. Contribute to openzfsonwindows/openzfs development by creating an account on GitHub.
github.com
OpenZFS on Windows 2.3.1 rc10 is out
OpenZFS on Windows is a filesystem driver for a regular OpenZFS and quite good now. Remaining Problems become more and more specific to special use cases or hardware
rc10
download: Releases · openzfsonwindows/openzfs
issues: openzfsonwindows/openzfs
OpenZFS on Windows is a filesystem driver for a regular OpenZFS and quite good now. Remaining Problems become more and more specific to special use cases or hardware
rc10
- Correct GroupSID to gid mapping, to fix permission denied
- Fix READ-ONLY mounts BSOD
- Add cbuf to OpenZVOL.sys
download: Releases · openzfsonwindows/openzfs
issues: openzfsonwindows/openzfs
Smartmontools is an important tool to check disks, with a Windows version available
To check disks, you need a list, usually done ith
smartctl --scan
/dev/sda -d nvme # /dev/sda, NVMe device
/dev/sdb -d scsi # /dev/sdb, SCSI device
On Windows not helpful as Windows names are physicaldriveX
but there is an option I didn't until now
smartctl -d pd --scan
/dev/pd0 -d nvme # /dev/pd0, NVMe device
/dev/pd1 -d scsi # /dev/pd1, SCSI device
pd0 is physicaldrive0
If you know, you can work with it
C:\Users\me>smartctl -HA /dev/pd0
smartctl 7.5 2025-04-30 r5714 [x86_64-w64-mingw32-w11-24H2] (AppVeyor)
Copyright (C) 2002-25, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
SMART/Health Information (NVMe Log 0x02, NSID 0xffffffff)
Critical Warning: 0x00
Temperature: 38 Celsius
Available Spare: 100%
Available Spare Threshold: 10%
Percentage Used: 4%
Data Units Read: 83,123,367 [42.5 TB]
Data Units Written: 75,626,349 [38.7 TB]
Host Read Commands: 920,395,240
Host Write Commands: 1,219,254,922
Controller Busy Time: 3,870
Power Cycles: 2,624
Power On Hours: 9,416
Unsafe Shutdowns: 177
Media and Data Integrity Errors: 0
Error Information Log Entries: 10,634
Warning Comp. Temperature Time: 0
Critical Comp. Temperature Time: 0
Temperature Sensor 1: 38 Celsius
Temperature Sensor 2: 43 Celsius
To check disks, you need a list, usually done ith
smartctl --scan
/dev/sda -d nvme # /dev/sda, NVMe device
/dev/sdb -d scsi # /dev/sdb, SCSI device
On Windows not helpful as Windows names are physicaldriveX
but there is an option I didn't until now
smartctl -d pd --scan
/dev/pd0 -d nvme # /dev/pd0, NVMe device
/dev/pd1 -d scsi # /dev/pd1, SCSI device
pd0 is physicaldrive0
If you know, you can work with it
C:\Users\me>smartctl -HA /dev/pd0
smartctl 7.5 2025-04-30 r5714 [x86_64-w64-mingw32-w11-24H2] (AppVeyor)
Copyright (C) 2002-25, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
SMART/Health Information (NVMe Log 0x02, NSID 0xffffffff)
Critical Warning: 0x00
Temperature: 38 Celsius
Available Spare: 100%
Available Spare Threshold: 10%
Percentage Used: 4%
Data Units Read: 83,123,367 [42.5 TB]
Data Units Written: 75,626,349 [38.7 TB]
Host Read Commands: 920,395,240
Host Write Commands: 1,219,254,922
Controller Busy Time: 3,870
Power Cycles: 2,624
Power On Hours: 9,416
Unsafe Shutdowns: 177
Media and Data Integrity Errors: 0
Error Information Log Entries: 10,634
Warning Comp. Temperature Time: 0
Critical Comp. Temperature Time: 0
Temperature Sensor 1: 38 Celsius
Temperature Sensor 2: 43 Celsius
OpenZFSOnWindows 2.3.1 RC9 to RC10v4
Broken after install. "zfs list" don't works anymore, nothing works.
Honestly, it's unreliable.
Broken after install. "zfs list" don't works anymore, nothing works.
Code:
zfs list
zpool import usb
/dev/zfs and /proc/self/mounts are required.
Try running 'udevadm trigger' and 'mount -t proc proc /proc' as root.2.3.1 rc10v4 is a debug interim release to try to fix a problem with openzvol and ghost installs.
If fixed the openzvol problem and removes ghost installs but failes to install openzfs.sys afterwards (this is what the error means)
To fix the problem: Just rerun the v4 installer again.
github.com
If fixed the openzvol problem and removes ghost installs but failes to install openzfs.sys afterwards (this is what the error means)
To fix the problem: Just rerun the v4 installer again.
rc10: Openzvol.sys not started · Issue #501 · openzfsonwindows/openzfs
System information Type Version/Name Distribution Name Distribution Version Kernel Version rc10 Architecture Win11 Pro 24.02 OpenZFS Version 2.3.1rc10 Describe the problem you're observing openzvol...
github.com