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(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".
+
+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..
+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(a)redhat.com>