On 05/27/16 at 05:39pm, Xunlei Pang wrote:
On 2016/05/27 at 14:39, Xunlei Pang wrote:
> On 2016/05/27 at 14:00, Dave Young wrote:
>> Hi, Xunlei
>>
>> On 05/26/16 at 09:08pm, Xunlei Pang wrote:
>>> Update "kexec-kdump-howto" to illustrate the usage of special
mount
>>> information via "dracut_args".
>>>
>>> Suggested-by: Dave Young <dyoung(a)redhat.com>
>>> Signed-off-by: Xunlei Pang <xlpang(a)redhat.com>
>>> ---
>>> kexec-kdump-howto.txt | 31 +++++++++++++++++++++++++++++++
>>> 1 file changed, 31 insertions(+)
>>>
>>> diff --git a/kexec-kdump-howto.txt b/kexec-kdump-howto.txt
>>> index b4cdc22..f7c6811 100644
>>> --- a/kexec-kdump-howto.txt
>>> +++ b/kexec-kdump-howto.txt
>>> @@ -345,6 +345,37 @@ mount the NFS mount and copy out the vmcore to your NFS
server. Restart the
>>> kdump service via '/sbin/systemctl restart kdump.service' to commit
this change
>>> to your kdump initrd.
>>>
>>> +Special mount via "dracut_args"
>>> +
>>> +Kdump uses dracut to generate initramfs for second kernel. This option
>>> +allows a user to pass arguments to dracut directly.
>>> +
>>> +Users can utilize "dracut_args" to pass "--mount" to
kdump, please refer
>>> +to "man dracut" for the format of "--mount" argument.
If there is any
>>> +"--mount" specified via "dracut_args", kdump always
uses it as the final
>>> +mount target without any validation(mounting or checking like mount
options,
>>> +fs size, save path, etc), so users are expected to ensure all the
correctness.
>>> +It conflicts with targets specified via
"ext[234]/xfs/btrfs/nfs".
>> What is the behavior for ssh dump in /etc/kdump.conf being used?
> It will fail as well due to "More than one dump targets specified."
> Missed ssh, I will add "ssh" here. Thanks for the catching.
>
>>> +
>>> +This is useful when we want to deploy thoundsands of diskless clients
using
>>> +nfs dumping and share the same nfs server. In this scenario, each time the
>>> +clients are booting up, the kdump initramfs rebuild will be triggered due
to
>>> +the diskless environment, so all the clients will request nfs mount
simultaneouly,
>>> +thereby imposing very much burdon on the shared nfs server. With the help
of
>>> +special mount via "dracut_args", kdump can skip mounting and
resolve the issue.
>>> +Because nfs needn't to be mounted beforehand, some nfs-related ko
modules will
>>> +be explicitly specified as needed together in the
"dracut_args"(or via directive
>>> +"extra_modules" in /etc/kdump.conf). As an nfs mount example:
>>> +dracut_args --mount "192.168.1.1:/test /test nfs defaults"
--add-driver "nfs nfsv4"
>> For the stateless system use case, it is possible to avoid rebuilding during
>> every boot. Ie. use a workable initrd with timestamp earlier then
/etc/kdump.conf
>> when admin create the rootfs etc. It is just a guess but there might be ways to
>> do it. It seems not proper being used in the documentaion.
>>
>> How about just say that one use case is for nfs dump some admin may not want
nfs
>> server being mounted first.
> Sure
How about the modified description below:
Special mount via "dracut_args"
Kdump uses dracut to generate initramfs for second kernel. This option
allows a user to pass arguments to dracut directly.
Above paragraph is not necessary because it has been documented in both
kdump.conf comments and manpage.
>
> Users can utilize "dracut_args" to pass "--mount" to kdump,
please refer
> to "man dracut" for the format of "--mount" argument. If there is
any
> "--mount" specified via "dracut_args", kdump always uses it as
the final
> mount target without any validation(mounting or checking like mount options,
> fs size, save path, etc), so users are expected to ensure all the correctness.
> It conflicts with targets specified via "ext[234]/xfs/btrfs/nfs/ssh".
>
> This is useful when administrators don't want the dump target being mounted
> first. Since the dump target needn't to be mounted beforehand, some fs-related
> ko modules will be explicitly specified as needed together in the
"dracut_args"
> (or via directive "extra_modules" in /etc/kdump.conf). As an nfs mount
example:
> dracut_args --mount "192.168.1.1:/test /test nfs defaults" --add-driver
"nfs nfsv4"
>
> NOTE:
> -Only one mount target is allowed using "dracut_args" globally.
> -Dracut will create <mountpoint> if it doesn't exist in kdump kernel,
> <mountpoint> must be specified in an absolute path.
> -There must be double quotation marks behind "--mount", i.e. --mount
"<mount info>".
> -Users should do a test first and ensure it works, because kdump does
> not prepare the mount and check all the validity.
>
> >
> > Regards,
> > Xunlei
> >
> >>> +
> >>> +NOTE:
> >>> +-Only one mount target is allowed using "dracut_args"
globally.
> >>> +-Dracut will create <mountpoint> if it doesn't exist in kdump
kernel,
> >>> + <mountpoint> must be specified in an absolute path.
> >>> +-There must be double quotation marks behind "--mount", i.e.
--mount "<mount info>".
> >>> +-Users should do a test first and ensure it works, because kdump does
> >>> + not prepare the mount and check all the validity.
> >>> +
> >>> Remote system via ssh/scp
> >>>
> >>> Dumping over ssh/scp requires setting up passwordless ssh keys for
every
> >>> --
> >>> 1.8.3.1
> >>> _______________________________________________
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> >>>
https://lists.fedoraproject.org/admin/lists/kexec@lists.fedoraproject.org
> >> Thanks
> >> Dave
> > _______________________________________________
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