First ploop partition was not detected properly, please call partx/partprobe manually

[kiranos]

I have centos 7 with a compiled nbd module but I get:

ploop_userspace /home/test/root.hdd/root.hdd
We process: /home/test/root.hdd/root.hdd
Ploop file size is: 6224347136
version: 2 disk type: 2 heads count: 16 cylinder count: 81920 sector count: 2048 size in tracks: 20480 size in sectors: 41943040 disk in use: 1953459801 first
For storing 21474836480 bytes on disk we need 20480 ploop blocks
We have 1 BAT blocks
We have 262128 slots in 1 map
Number of non zero blocks in map: 5935
Please be careful because this disk used now! If you need consistent backup please stop VE
We found GPT table on this disk
We found ext4 signature at first partition block
Set device /dev/nbd0 as read only
Try to found partitions on ploop device
First ploop partition was not detected properly, please call partx/partprobe manually
You could mount ploop filesystem with command: mount -r -o noload /dev/nbd0p1 /mnt

and after above line it just stalls, it doesnt go anywhere. There is a partition and all as I can mount it on a openvz kernel. (RHEL6)

[mrqwer88]

Hello!

Are you try run partx/partprobe?
Are output

parted /dev/nbd0 p

or same command looks good?

[kiranos]

Hi yes it seems to look good:

# parted /dev/nbd0 p
Model: Unknown (unknown)
Disk /dev/nbd0: 21.5GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number  Start   End     Size    File system  Name     Flags
 1      1049kB  21.5GB  21.5GB  ext4         primary

But ls doesnt show an nbd0p1 partition.

# ls /dev/nbd
nbd0   nbd1   nbd10  nbd11  nbd12  nbd13  nbd14  nbd15  nbd2   nbd3   nbd4   nbd5   nbd6   nbd7   nbd8   nbd9

also the command is still stalled at You could mount ploop filesystem with command: mount -r -o noload /dev/nbd0p1 /mnt I did not get a prompt back so its still at halt.

[kiranos]

with partx I get:

 partx -a /dev/nbd0
partx: /dev/nbd0: error adding partition 1

[mrqwer88]

Sorry for late answer.

Try to load nbd module with max_part param like -

modprobe nbd max_part=16

It fixed this issue for me in test centos 7 install.

[jas8522]

I'm having this exact same issue. A manual run of parted results in:

# parted /dev/nbd0 p
Model: Unknown (unknown)
Disk /dev/nbd0: 161GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End    Size   File system  Name  Flags
 1      1049kB  161GB  161GB  ext4

I tried running modprobe nbd max_part=16 but it didn't seem to make a difference: it still can't find the partition. Any other ideas?

CentOS Linux release 7.4.1708 (Core)

[mrqwer88]

Just running or load moule nbd with max_part=16 ?
In some version max_part by default - 0.
Are you try to check actual max_part like

cat /sys/module/nbd/parameters/max_part

?

I reproduced this with max_part = 0, but not reproduced with max_part=16.
This tool try to load module with max_part=16 -

ploop_userspace/ploop.cpp

Line 602 in cab3eca

system("modprobe nbd max_part=16 2>&1 >/dev/null");

But it work only if module not loaded yet.

[javildn]

I reproduced the same problem in a Openvz7 default installation.

cat /sys/module/nbd/parameters/max_part

31

Any idea?

[mrqwer88]

Sorry, cannot reproduce it now with vzkernel 3.10.0-957.12.2.vz7.96.21 and

cat /sys/module/nbd/parameters/max_part
31

Are ploop_userspace give some errors on warnings?
with TRACE_REQUESTS=1 too?

[javildn]

This is the error now:

TRACE_REQUESTS=1 ./ploop_userspace 101

We process: /vz/private/101/root.hdd/root.hds
Ploop file size is: 1021313024
version: 2 disk type: 2 heads count: 16 cylinder count: 40960 sector count: 2048 size in tracks: 10240 size in sectors: 20971520 disk in use: 1953459801 first block offset: 2048 flags: 0
For storing 10737418240 bytes on disk we need 10240 ploop blocks
We have 1 BAT blocks
We have 262128 slots in 1 map
Number of non zero blocks in map: 846
Please be careful because this disk used now! If you need consistent backup please stop VE
We got request for reading from offset: 512 length 8 bytes to the end: 520
ploop cluster size: 1048576
global first block offset: 1048576
global ploop block device size 10737418240
data_page_number: 0
data_page_real_place: 1
offset for current page: 512
ploop file size: 1021313024
position_in_file: 1049088

We found GPT table on this disk
We got request for reading from offset: 1049656 length 2 bytes to the end: 1049658
ploop cluster size: 1048576
global first block offset: 1048576
global ploop block device size 10737418240
data_page_number: 1
data_page_real_place: 3
offset for current page: 1080
ploop file size: 1021313024
position_in_file: 3146808

We found ext4 signature at first partition block
We got request for reading from offset: 1080 length 2 bytes to the end: 1082
ploop cluster size: 1048576
global first block offset: 1048576
global ploop block device size 10737418240
data_page_number: 0
data_page_real_place: 1
offset for current page: 1080
ploop file size: 1021313024
position_in_file: 1049656

Set device /dev/nbd0 as read only
We got request for reading from offset: 0 length 4096 bytes to the end: 4096
ploop cluster size: 1048576
global first block offset: 1048576
global ploop block device size 10737418240
data_page_number: 0
data_page_real_place: 1
offset for current page: 0
ploop file size: 1021313024
position_in_file: 1048576

We got request for reading from offset: 4096 length 4096 bytes to the end: 8192
ploop cluster size: 1048576
global first block offset: 1048576
global ploop block device size 10737418240
data_page_number: 0
data_page_real_place: 1
offset for current page: 4096
ploop file size: 1021313024
position_in_file: 1052672

Try to found partitions on ploop device
We got request for reading from offset: 0 length 16384 bytes to the end: 16384
ploop cluster size: 1048576
global first block offset: 1048576
global ploop block device size 10737418240
data_page_number: 0
data_page_real_place: 1
offset for current page: 0
ploop file size: 1021313024
position_in_file: 1048576

We got request for reading from offset: 16384 length 32768 bytes to the end: 49152
ploop cluster size: 1048576
global first block offset: 1048576
global ploop block device size 10737418240
data_page_number: 0
data_page_real_place: 1
offset for current page: 16384
ploop file size: 1021313024
position_in_file: 1064960

First ploop partition was not detected properly, please call partx/partprobe manually
You could mount ploop filesystem with command: mount -r -o noload /dev/nbd0p1 /mnt

[javildn]

Ok, I found the problem, it works with 3.10.0-957.12.2.vz7.96.21 kernel but it doesn't with latest kernel from factory.repo (3.10.0-1062.7.1.vz7.130.1)

[mrqwer88]

factory is testing branch, not recommended to use it in production.
And it can have some errors and issues which not fixed yet.
Looked like it have some issues with ndb module at this time.

[javildn]

I tried in a Proxmox 6 server running kernel 5 and got the same error, maybe the problem is related to new kernels, and will appear too in the default repo in Openvz7 when they update kernel.

[mrqwer88]

Sorry for late answer.

maybe the problem is related to new kernels

@javildn And you was right.

Reproduced problem with new vz7 vzkernel.

parted /dev/nbd0 p
Error: /dev/nbd0: unrecognised disk label
Model: Unknown (unknown)                                                  
Disk /dev/nbd0: 50.3GB
Sector size (logical/physical): 1024B/1024B
Partition Table: unknown
Disk Flags:

Looks like default NBD_DEF_BLKSIZE was changed from 512 to 1024 and it broke ploop_userspace.

I have update BUSE and set blksize today, should work now -

 parted /dev/nbd0 p
Model: Unknown (unknown)
Disk /dev/nbd0: 50.3GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name     Flags
 1      1049kB  50.3GB  50.3GB  ext4         primary



mount -r -o noload /dev/nbd0p1 /mnt
df -h /mnt/
Filesystem      Size  Used Avail Use% Mounted on
/dev/nbd0p1      47G   35G   11G  76% /mnt

[dudekaa]

@mrqwer88 Thank you very much!

Newest version works for me on Fedora 30, kernel 5.4.12-100.fc30.x86_64.