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Re: LVM support
From: |
Ludovic Courtès |
Subject: |
Re: LVM support |
Date: |
Sun, 03 May 2015 21:59:53 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Sorry for the delay.
Tomáš Čech <address@hidden> skribis:
> On Tue, Apr 21, 2015 at 05:52:33PM +0200, Ludovic Courtès wrote:
[...]
>>So I would declare
>>
>> (mapped-device
>> (source "/dev/sda")
>> (target "volume_group_name-logical_volume_name")
>> (kind lvm-device-mapping))
>>
>>and that would give me
>>/dev/mapper/volume_group_name-logical_volume_name, right?
>
> Volume group can be on multiple block devices. For now I rely on autodetect
> abilities of LVM.
>
> So you would declare:
>
> (mapped-device
> (source "") ; irrelevant for LVM
> (target "volume_group_name")
> (type lvm-mapping))
>
> and that would give you
> /dev/mapper/volume_group_name-some_volume
> /dev/mapper/volume_group_name-other_volume
> ...
>
> and more conveniently
> /dev/volume_group_name/some_volume
> /dev/volume_group_name/other_volume
> ...
OK. So the ‘source’ is irrelevant because ‘vgscan’ magically creates
the device nodes for volumes such that users don’t have to know what the
underlying block devices are, right?
[...]
>>> (boot-system #:mounts '#$(map file-system->spec file-systems)
>>> #:pre-mount (lambda ()
>>> - (and address@hidden))
>>> + (and address@hidden
>>> + ;; If we activated any volume
>>> group, we
>>> + ;; need to ensure that device
>>> nodes are
>>> + ;; created. Add code here to
>>> call it
>>> + ;; once for all activations.
>>> + #$(when (lvm-mapping-used?
>>> mapped-devices)
>>> + #~(zero?
>>> + (system* (string-append
>>> + #$lvm2/static
>>> +
>>> "/sbin/lvm.static")
>>> + "vgscan"
>>> + "--mknodes")))))
>>
>>So ‘lvm vgchange --activate y’ does not create /dev nodes?
>
> Right.
>
>>Would it be possible to change the command returned by
>>‘logical-volume-group-activate’ to somehow create the nodes? That would
>>be ideal.
>
> There are two actions needed to be taken:
> 1] volume group activation
> 2] creation of nodes
>
> This design choice does as many 1] as needed and 2] once in the end.
>
> I could do always 1] and 2] for every volume group, but I didn't find it nice,
> since previous 2] calls are useless only slowing down the process. Do you
> really think I should change it?
No, you’re right, what you did makes a lot of sense (thanks for bearing
with me!).
Could you send an updated patch? It sounds like we’re almost there,
I guess.
Thanks,
Ludo’.
- Re: LVM support, Tomáš Čech, 2015/05/01
- Re: LVM support,
Ludovic Courtès <=