FS (dm-0): device supports 4096 byte sectors (not 512)

FS (dm-0): device supports 4096 byte sectors (not 512)

[Johnatan Hallman]

Hello List,

I get this error when I try to mount an XFS partition.
Fortunately there is no critical data on it as it is just a backup but I would still like to mount it if it's possible.

I have tried with various Linux distros with kernels ranging from 5.6 to 6.1 it's the same result.

xfs_info /dev/mapper/test
meta-data=/dev/mapper/test       isize=256    agcount=32, agsize=30523559 blks
         =                       sectsz=512   attr=2, projid32bit=0
         =                       crc=0        finobt=0, sparse=0, rmapbt=0
         =                       reflink=0    bigtime=0 inobtcount=0 nrext64=0
data     =                       bsize=4096   blocks=976753869, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=0
log      =internal log           bsize=4096   blocks=476930, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

mount -t xfs -o ro /dev/mapper/test  /mnt/
mount: /mnt: mount(2) system call failed: Function not implemented.
       dmesg(1) may have more information after failed mount system call.

Re: FS (dm-0): device supports 4096 byte sectors (not 512)

[Eric Sandeen]

On 3/23/23 5:45 AM, Johnatan Hallman wrote:
> Hello List,
> 
> I get this error when I try to mount an XFS partition.
> Fortunately there is no critical data on it as it is just a backup but I would still like to mount it if it's possible.
> 
> I have tried with various Linux distros with kernels ranging from 5.6 to 6.1 it's the same result.
> 
> xfs_info /dev/mapper/test
> meta-data=/dev/mapper/test       isize=256    agcount=32, agsize=30523559 blks
>          =                       sectsz=512   attr=2, projid32bit=0
>          =                       crc=0        finobt=0, sparse=0, rmapbt=0
>          =                       reflink=0    bigtime=0 inobtcount=0 nrext64=0
> data     =                       bsize=4096   blocks=976753869, imaxpct=5
>          =                       sunit=0      swidth=0 blks
> naming   =version 2              bsize=4096   ascii-ci=0, ftype=0
> log      =internal log           bsize=4096   blocks=476930, version=2
>          =                       sectsz=512   sunit=0 blks, lazy-count=1
> realtime =none                   extsz=4096   blocks=0, rtextents=0
> 
> mount -t xfs -o ro /dev/mapper/test  /mnt/
> mount: /mnt: mount(2) system call failed: Function not implemented.
>        dmesg(1) may have more information after failed mount system call.

So I assume dmesg contained the error in $SUBJECT:

FS (dm-0): device supports 4096 byte sectors (not 512)

It seems that the filesystem was created with 512-byte sectors - at that time, the device
must have supported them. Perhaps something about the devicemapper target changed from
a 512 device to a 4k device? I'm not sure what might cause that to happen, but IMHO
it should never happen... did the dm device recently get reconfigured?

As a last resort, I think you could dd the filesystem (all 3T) to a file, and use a
loopback mount to access the files.

Alternatively, I wonder if we could relax the sector size check for a read-only
mount (that does not require log replay) - I'm not sure about that though.

-Eric

Re: FS (dm-0): device supports 4096 byte sectors (not 512)

[Johnatan Hallman]

Hello,

It's a single luks encrypted disk, nothing complex is going on. I don't get it either how that changed. 

NAME                MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda                   8:0    0   3.7T  0 disk  
`-test              254:1    0   3.7T  0 crypt 

There is no problem with the encryption it can be opened. 

test	(254:1)

I have tried to open it like this, same story:

cryptsetup --verbose -b 512 luksOpen /dev/sda test

------- Original Message -------
On Thursday, March 23rd, 2023 at 4:39 PM, Eric Sandeen <sandeen@sandeen.net> wrote:


> On 3/23/23 5:45 AM, Johnatan Hallman wrote:
> 
> > Hello List,
> > 
> > I get this error when I try to mount an XFS partition.
> > Fortunately there is no critical data on it as it is just a backup but I would still like to mount it if it's possible.
> > 
> > I have tried with various Linux distros with kernels ranging from 5.6 to 6.1 it's the same result.
> > 
> > xfs_info /dev/mapper/test
> > meta-data=/dev/mapper/test isize=256 agcount=32, agsize=30523559 blks
> > = sectsz=512 attr=2, projid32bit=0
> > = crc=0 finobt=0, sparse=0, rmapbt=0
> > = reflink=0 bigtime=0 inobtcount=0 nrext64=0
> > data = bsize=4096 blocks=976753869, imaxpct=5
> > = sunit=0 swidth=0 blks
> > naming =version 2 bsize=4096 ascii-ci=0, ftype=0
> > log =internal log bsize=4096 blocks=476930, version=2
> > = sectsz=512 sunit=0 blks, lazy-count=1
> > realtime =none extsz=4096 blocks=0, rtextents=0
> > 
> > mount -t xfs -o ro /dev/mapper/test /mnt/
> > mount: /mnt: mount(2) system call failed: Function not implemented.
> > dmesg(1) may have more information after failed mount system call.
> 
> 
> So I assume dmesg contained the error in $SUBJECT:
> 
> FS (dm-0): device supports 4096 byte sectors (not 512)
> 
> It seems that the filesystem was created with 512-byte sectors - at that time, the device
> must have supported them. Perhaps something about the devicemapper target changed from
> a 512 device to a 4k device? I'm not sure what might cause that to happen, but IMHO
> it should never happen... did the dm device recently get reconfigured?
> 
> As a last resort, I think you could dd the filesystem (all 3T) to a file, and use a
> loopback mount to access the files.
> 
> Alternatively, I wonder if we could relax the sector size check for a read-only
> mount (that does not require log replay) - I'm not sure about that though.
> 
> -Eric

Re: FS (dm-0): device supports 4096 byte sectors (not 512)

[Dave Chinner]

On Thu, Mar 23, 2023 at 10:45:18AM +0000, Johnatan Hallman wrote:
> Hello List,
> 
> I get this error when I try to mount an XFS partition.
> Fortunately there is no critical data on it as it is just a backup but I would still like to mount it if it's possible.
> 
> I have tried with various Linux distros with kernels ranging from 5.6 to 6.1 it's the same result.
> 
> xfs_info /dev/mapper/test
> meta-data=/dev/mapper/test       isize=256    agcount=32, agsize=30523559 blks

Where did this filesystem come from? It's a v4 filesystem, so
unless you specifically made it that way it must be a pretty old
filesystem.

What is the drive hardware and how is it connected to the machine?
e.g. perhaps it is an an external drive connected through a USB-SATA
bridge and the bridge hardware might be advertising the drive as a
4kB sector drive incorrectly?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: FS (dm-0): device supports 4096 byte sectors (not 512)

[Johnatan Hallman]

Hello,

Thanks a lot, that was it. I never thought of it. The usb docking station was changed now I tried with another one works fine :)



------- Original Message -------
On Friday, March 24th, 2023 at 12:18 AM, Dave Chinner <david@fromorbit.com> wrote:


> On Thu, Mar 23, 2023 at 10:45:18AM +0000, Johnatan Hallman wrote:
> 
> > Hello List,
> > 
> > I get this error when I try to mount an XFS partition.
> > Fortunately there is no critical data on it as it is just a backup but I would still like to mount it if it's possible.
> > 
> > I have tried with various Linux distros with kernels ranging from 5.6 to 6.1 it's the same result.
> > 
> > xfs_info /dev/mapper/test
> > meta-data=/dev/mapper/test isize=256 agcount=32, agsize=30523559 blks
> 
> 
> Where did this filesystem come from? It's a v4 filesystem, so
> unless you specifically made it that way it must be a pretty old
> filesystem.
> 
> What is the drive hardware and how is it connected to the machine?
> e.g. perhaps it is an an external drive connected through a USB-SATA
> bridge and the bridge hardware might be advertising the drive as a
> 4kB sector drive incorrectly?
> 
> Cheers,
> 
> Dave.
> --
> Dave Chinner
> david@fromorbit.com