[ISSUE] Data loose on lvm after reboot

[ISSUE] Data loose on lvm after reboot

[superiums]

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New issue by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589

Description:
i have two ext4 logical volum, one normal, one with luks crypt.
one day i found all data on luks lost. but the lv can be mounted normally, and fsck found no err.
i reformated it with luksFormat and mkfs.ex4. then tried seral times to write, and found:
- before reboot, everything goes right. write ok, read ok, size ok.
- after reboot, everything has gone, even folders, the volum seems newly formatted. 
- even exec `sync ` command, everything lost after reboot most time, only once the folder was kept.
- if write in arch instead of voidLinux, the files was kept , could be seen in both arch and void.
- if write something in voidLinux again, write ok, read ok, but after reboot, everything lost., **including the existing files**.
- fsck found no err.

all these situation happens in both luks lv and normal lv.

## additional

- my void system and home was also on lvm, but never loose.
- the normal lv which loose data was newly formatted in void. before this action, it works ok in other system.
- these volum was mounted manually without fstab.

## versions
- void linux, kernel 5.19.17_1 
- wayland
- wayfire 0.7.3
- thunar 4.6.11
- foot 1.13.1

Re: Data loose on lvm after reboot

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1320961246

Comment:
You should probably post your `/etc/crypttab` and clarify what you mean by "mount point i usually use `/dev/shm/xxx`". None of your physical disks or LVM devices should be in `/dev/shm`.

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1321076543

Comment:
> You should probably post your `/etc/crypttab` and clarify what you mean by "mount point i usually use `/dev/shm/xxx`". None of your physical disks or LVM devices should be in `/dev/shm`.

i mean i usually do like this:
```
sudo mount /dev/mapper/vg-lv3   /dev/shm/lv3

```
sorry for my unclear description.
my lv was not listed in `/etc/crypttab`

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1321076542

Comment:
> You should probably post your `/etc/crypttab` and clarify what you mean by "mount point i usually use `/dev/shm/xxx`". None of your physical disks or LVM devices should be in `/dev/shm`.

i mean i usually do like this:
```
sudo mount /dev/mapper/vg-lv3   /dev/shm/lv3

```

my lv was not listed in `/etc/crypttab`

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1321076542

Comment:
> You should probably post your `/etc/crypttab` and clarify what you mean by "mount point i usually use `/dev/shm/xxx`". None of your physical disks or LVM devices should be in `/dev/shm`.

i mean i usually do like this:
```
sudo mount /dev/mapper/vg-lv3   /dev/shm/lv3

```

my lv was not listed in `/etc/crypttab`

Re: Data loose on lvm after reboot

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1321122125

Comment:
Why are you mounting things under `/dev/shm`? That's ill advised.

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1321549194

Comment:
> Why are you mounting things under `/dev/shm`? That's ill advised.

aha, got it ! this is the reason which caused the issue.
i've tried to mount lv to /media/xxx, and it never loose now.

i mount it to /dev/shm/xxx for temp use, usuallay i use /dev/shm as temp directory.
before use void linux, in arch, there's no problem in this way. 
but seems in voidLinux it works in different way from other os .

i'm now interesting with why mount to /dev/shm/xxx will cause data loose.

Re: Data loose on lvm after reboot

[sgn]

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New comment by sgn on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1321689212

Comment:
Do you have `elogind` installed and enabled?

Re: [ISSUE] [CLOSED] Data loose on lvm after reboot

[ahesford]

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Closed issue by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589

Description:
i have two ext4 logical volum, one normal, one with luks crypt.
one day i found all data on luks lost. but the lv can be mounted normally, and fsck found no err.
i reformated it with luksFormat and mkfs.ex4. then tried seral times to write, and found:
- before reboot, everything goes right. write ok, read ok, size ok.
- after reboot, everything has gone, even folders, the volum seems newly formatted. 
- even exec `sync ` command, everything lost after reboot most time, only once the folder was kept.
- if write in arch instead of voidLinux, the files was kept , could be seen in both arch and void.
- if write something in voidLinux again, write ok, read ok, but after reboot, everything lost., **including the existing files**.
- fsck found no err.

all these situation happens in both luks lv and normal lv.

## additional

- my void system and home was also on lvm, but never loose.
- the normal lv which loose data was newly formatted in void. before this action, it works ok in other system.
- these volum was mounted manually without fstab.
- i usually mount volums to /dev/shm/xxx


## versions
- void linux, kernel 5.19.17_1 
- wayland
- wayfire 0.7.3
- thunar 4.6.11
- foot 1.13.1
- lvm2-2.02.187_2
- libllvm12-12.0.1_4
- cryptsetup-2.5.0_1

Re: Data loose on lvm after reboot

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1322033667

Comment:
`/dev/shm` is used by the shared-memory interface and not intended for direct use by users. In general, you should never mount thing inside `/dev`.

Re: Data loose on lvm after reboot

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1322033667

Comment:
~~`/dev/shm` is used by the shared-memory interface and not intended for direct use by users.~~ In general, you should never mount thing inside `/dev`.

Edit: turns out `/dev/shm` is just a tmpfs mount and is intended for users to store things guaranteed not to be on disk (this seems like a poorly developed concept, because you shouldn't expect any particular storage behavior based solely on where you save and read files), but that has no bearing on the recommendation against mounting things under `/dev/`

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1323723532

Comment:
> Do you have `elogind` installed and enabled?

yes , elogind was installed, and started.
but the service was not enabled.
maybe started by greetd.

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1323723547

Comment:
> Do you have `elogind` installed and enabled?

yes , elogind was installed, and started.
but the service was not enabled.
maybe started by greetd.

> ~`/dev/shm` is used by the shared-memory interface and not intended for direct use by users.~ In general, you should never mount thing inside `/dev`.
> 
> Edit: turns out `/dev/shm` is just a tmpfs mount and is intended for users to store things guaranteed not to be on disk (this seems like a poorly developed concept, because you shouldn't expect any particular storage behavior based solely on where you save and read files), but that has no bearing on the recommendation against mounting things under `/dev/`

thank you very much!

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1323723547

Comment:

> ~`/dev/shm` is used by the shared-memory interface and not intended for direct use by users.~ In general, you should never mount thing inside `/dev`.
> 
> Edit: turns out `/dev/shm` is just a tmpfs mount and is intended for users to store things guaranteed not to be on disk (this seems like a poorly developed concept, because you shouldn't expect any particular storage behavior based solely on where you save and read files), but that has no bearing on the recommendation against mounting things under `/dev/`

thank you very much!

Re: Data loose on lvm after reboot

[sgn]

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New comment by sgn on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1323743426

Comment:
`/dev/shm` is for SHared Memory IPC, it will be cleaned up up on logging out. https://github.com/systemd/systemd/issues/2039

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1324544967

Comment:
> `/dev/shm` is for SHared Memory IPC, it will be cleaned up up on logging out. [systemd/systemd#2039](https://github.com/systemd/systemd/issues/2039)

yeh, files in it will be cleaned.
but mount device to it , data is not saved in it. 
in arch , no data will loose if do the same thing.

Re: Data loose on lvm after reboot

[superiums]

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New comment by superiums on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1324544967

Comment:
> `/dev/shm` is for SHared Memory IPC, it will be cleaned up up on logging out. [systemd/systemd#2039](https://github.com/systemd/systemd/issues/2039)

yeh, files in it will be cleaned.
but mount device to it , data is not saved in it. 
in arch and ubuntu , no data will loose if do the same thing.

maybe the mount options differs from each other.

Re: Data loose on lvm after reboot

[sgn]

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New comment by sgn on void-packages repository

https://github.com/void-linux/void-packages/issues/40589#issuecomment-1324654532

Comment:
Noone care if it's a normal directory or mount-point:

https://github.com/systemd/systemd/blob/d9338387d94ad611233cf0753801eefccfda432a/src/shared/clean-ipc.c#L221-L300

Re: arch and Ubuntu, I don't know your configuration, I can't comment.