Hi, Xunlei
Seems I sent wrong draft, here is the right one:
Add a question about below
--add-driver "nfs nfsv4"
Why should we add them? if we addes dracut 95nfs module then it will install
all the nfs kernel modules and network module.
But I have a concern, if the network can be setup correctly. Kdump still will
find the right nic and set it up?
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
s/Users/One, or s/Users/You
But we need keep consistently use either one or you in the following paragraph.
to "man dracut" for the format of "--mount"
argument. If there is any
Dropping needless politeness:
s/please refer to "man dracut" for the format of "--mount"
argument/see the dracut
manpage about "--mount" for details.
I found a guideline of documentation, though it is for openstack, but some
general rules also fit for other documentations:
http://docs.openstack.org/contributor-guide/writing-style/general-writing...
"--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".
Kdump uses "--mount" provided in dracut_args without sanity checking so you
must test it and ensure the correctness. You can not use other targets
in /etc/kdump.conf if you use "--mount" in dracut_args.
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"
This paragraph should be put before the usage paragraph so that it is more
natrual. How about simplify it as below:
A use case of "--mount" in dracut_args is you do not want to mount dump target
before kdump service startup, for example, to reduce the burden of nfs server.
Such as below example:
dracut_args --mount "192.168.1.1:/test /test nfs defaults"
NOTE:
-Only one mount target is allowed using "dracut_args" globally.
Already mentioned above, either drop above clarification or drop this item here.
-Dracut will create <mountpoint> if it doesn't exist in
kdump kernel,
<mountpoint> must be specified in an absolute path.
We do not need explain the internal details, just mention about it must be 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.
Also duplicated with previous sentences above.
>
> >
> > 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
> >>> _______________________________________________
> >>> kexec mailing list
> >>> kexec(a)lists.fedoraproject.org
> >>>
https://lists.fedoraproject.org/admin/lists/kexec@lists.fedoraproject.org
> >> Thanks
> >> Dave
> > _______________________________________________
> > kexec mailing list
> > kexec(a)lists.fedoraproject.org
> >
https://lists.fedoraproject.org/admin/lists/kexec@lists.fedoraproject.org
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