Re: degraded permanent mount option

[Duncan <1i5t5.duncan@cox.net>]

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.

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.

-- 
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"Every nonfree program has a lord, a master --
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