Re: degraded permanent mount option

[Andrei Borzenkov <arvidjaar@gmail.com>]

28.01.2018 18:57, Duncan пишет:
> Andrei Borzenkov posted on Sun, 28 Jan 2018 11:06:06 +0300 as excerpted:
> 
>> 27.01.2018 18:22, Duncan пишет:
>>> Adam Borowski posted on Sat, 27 Jan 2018 14:26:41 +0100 as excerpted:
>>>
>>>> On Sat, Jan 27, 2018 at 12:06:19PM +0100, Tomasz Pala wrote:
>>>>> On Sat, Jan 27, 2018 at 13:26:13 +0300, Andrei Borzenkov wrote:
>>>>>
>>>>>>> I just tested to boot with a single drive (raid1 degraded), even
>>>>>>> with degraded option in fstab and grub, unable to boot !  The boot
>>>>>>> process stop on initramfs.
>>>>>>>
>>>>>>> Is there a solution to boot with systemd and degraded array ?
>>>>>>
>>>>>> No. It is finger pointing. Both btrfs and systemd developers say
>>>>>> everything is fine from their point of view.
>>>>
>>>> It's quite obvious who's the culprit: every single remaining rc system
>>>> manages to mount degraded btrfs without problems.  They just don't try
>>>> to outsmart the kernel.
>>>
>>> No kidding.
>>>
>>> All systemd has to do is leave the mount alone that the kernel has
>>> already done,
>>
>> Are you sure you really understand the problem? No mount happens because
>> systemd waits for indication that it can mount and it never gets this
>> indication.
> 
> As Tomaz indicates, I'm talking about manual mounting (after the initr* 
> drops to a maintenance prompt if it's root being mounted, or on manual 
> mount later if it's an optional mount) here.  The kernel accepts the 
> degraded mount and it's mounted for a fraction of a second, but systemd 
> actually undoes the successful work of the kernel to mount it, so by the 
> time the prompt returns and a user can check, the filesystem is unmounted 
> again, with the only indication that it was mounted at all being the log.
> 

This is fixed in current systemd (actually for quite some time). If you
still observe it with more or less recent systemd, report a bug.

> He says that's because the kernel still says it's not ready, but that's 
> for /normal/ mounting.  The kernel accepted the degraded mount and 
> actually mounted the filesystem, but systemd undoes that.
>