On 2016/05/27 at 11:19, Pratyush Anand wrote:
On 26/05/2016:09:08:05 PM, Xunlei Pang wrote:
Update "kexec-kdump-howto" to illustrate the usage of special mount information via "dracut_args".
Suggested-by: Dave Young dyoung@redhat.com Signed-off-by: Xunlei Pang xlpang@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".
+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
^^^^^^^^^Probably "too much" would have been better wording..
Indeed, thanks!
Regards, Xunlei
+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"
+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
Other than that
Reviewed-by: Pratyush Anand panand@redhat.com