[Pacemaker] "Simple" LVM/drbd backed Primary/Secondary NFS cluster doesn't always failover cleanly
Andreas Kurz
andreas at hastexo.com
Sat Oct 20 23:38:46 UTC 2012
On 10/18/2012 08:02 PM, Justin Pasher wrote:
> I have a pretty basic setup by most people's standards, but there must
> be something that is not quite right about it. Sometimes when I force a
> resource failover from one server to the other, the clients with the NFS
> mounts don't cleanly migrate to the new server. I configured this using
> a few different "Pacemaker-DRBD-NFS" guides out there for reference (I
> believe they were the Linbit guides).
Are you using the latest "exportfs" resource-agent from github-repo? ...
there have been bugfixes/improvements... and try to move the VIP for
each export to the end of its group so the IP where the clients connect
is started at the last/stopped at the first position.
Regards,
Andreas
--
Need help with Pacemaker?
http://www.hastexo.com/now
>
> Sorry in advance for the long email.
>
> Here is the config:
> ------------------------------
> ------------------------------
> * Two identical servers
> * Four exported NFS shares total (so I can independently fail over
> individual shares and run half on one server and half on the other)
> * Bonded interface using LACP for "outgoing" client access
> * Direct ethernet connection between the two servers (for
> Pacemaker/Corosync and DRBD)
>
> Package versions (installed from either Debian Squeeze or Backports)
> * lvm 2.02.66-5
> * drbd 8.3.7-2.1
> * nfs-kernel-server 1.2.2-4squeeze2
> * pacemaker 1.1.7-1~bpo60+1
> * corosync 1.4.2-1~bpo60+1
>
> Each NFS share is created using the same component format and has its
> own virtual IP.
>
> Hardware RAID -> /dev/sdb -> LVM -> DRBD single master (one resource for
> each share)
>
>
> Here is the pacemaker config (I really hope it doesn't get mangled):
> ====================
> node storage1 \
> attributes standby="off"
> node storage2 \
> attributes standby="off"
> primitive p_drbd_distribion_storage ocf:linbit:drbd \
> params drbd_resource="distribion-storage" \
> op monitor interval="15" role="Master" \
> op monitor interval="30" role="Slave"
> primitive p_drbd_vni_storage ocf:linbit:drbd \
> params drbd_resource="vni-storage" \
> op monitor interval="15" role="Master" \
> op monitor interval="30" role="Slave"
> primitive p_drbd_xen_data1 ocf:linbit:drbd \
> params drbd_resource="xen-data1" \
> op monitor interval="15" role="Master" \
> op monitor interval="30" role="Slave"
> primitive p_drbd_xen_data2 ocf:linbit:drbd \
> params drbd_resource="xen-data2" \
> op monitor interval="15" role="Master" \
> op monitor interval="30" role="Slave"
> primitive p_exportfs_distribion_storage ocf:heartbeat:exportfs \
> params fsid="1" directory="/data/distribion-storage"
> options="rw,async,no_root_squash,subtree_check"
> clientspec="10.205.152.0/21" wait_for_leasetime_on_stop="false" \
> op monitor interval="30s"
> primitive p_exportfs_vni_storage ocf:heartbeat:exportfs \
> params fsid="2" directory="/data/vni-storage"
> options="rw,async,no_root_squash,subtree_check"
> clientspec="10.205.152.0/21" wait_for_leasetime_on_stop="false" \
> op monitor interval="30s"
> primitive p_exportfs_xen_data1 ocf:heartbeat:exportfs \
> params fsid="3" directory="/data/xen-data1"
> options="rw,async,no_root_squash,subtree_check"
> clientspec="10.205.152.0/21" wait_for_leasetime_on_stop="false" \
> op monitor interval="30s"
> primitive p_exportfs_xen_data2 ocf:heartbeat:exportfs \
> params fsid="4" directory="/data/xen-data2"
> options="rw,async,no_root_squash,subtree_check"
> clientspec="10.205.152.0/21" wait_for_leasetime_on_stop="false" \
> op monitor interval="30s"
> primitive p_fs_distribion_storage ocf:heartbeat:Filesystem \
> params fstype="xfs" directory="/data/distribion-storage"
> device="/dev/drbd1" \
> meta target-role="Started"
> primitive p_fs_vni_storage ocf:heartbeat:Filesystem \
> params fstype="xfs" directory="/data/vni-storage" device="/dev/drbd2"
> primitive p_fs_xen_data1 ocf:heartbeat:Filesystem \
> params fstype="xfs" directory="/data/xen-data1" device="/dev/drbd3" \
> meta target-role="Started"
> primitive p_fs_xen_data2 ocf:heartbeat:Filesystem \
> params fstype="xfs" directory="/data/xen-data2" device="/dev/drbd4" \
> meta target-role="Started"
> primitive p_ip_distribion_storage ocf:heartbeat:IPaddr2 \
> params ip="10.205.154.137" cidr_netmask="21" \
> op monitor interval="20s"
> primitive p_ip_vni_storage ocf:heartbeat:IPaddr2 \
> params ip="10.205.154.138" cidr_netmask="21" \
> op monitor interval="20s"
> primitive p_ip_xen_data1 ocf:heartbeat:IPaddr2 \
> params ip="10.205.154.139" cidr_netmask="21" \
> op monitor interval="20s"
> primitive p_ip_xen_data2 ocf:heartbeat:IPaddr2 \
> params ip="10.205.154.140" cidr_netmask="21" \
> op monitor interval="20s"
> primitive p_lsb_nfsserver lsb:nfs-kernel-server \
> op monitor interval="30s"
> primitive p_ping ocf:pacemaker:ping \
> params host_list="10.205.154.66" multiplier="100" \
> op monitor interval="15s" timeout="5s"
> group g_nfs_distribion_storage p_ip_distribion_storage
> p_fs_distribion_storage p_exportfs_distribion_storage
> group g_nfs_vni_storage p_ip_vni_storage p_fs_vni_storage
> p_exportfs_vni_storage \
> meta is-managed="true" target-role="Started"
> group g_nfs_xen_data1 p_ip_xen_data1 p_fs_xen_data1 p_exportfs_xen_data1
> group g_nfs_xen_data2 p_ip_xen_data2 p_fs_xen_data2 p_exportfs_xen_data2
> ms ms_drbd_distribion_storage p_drbd_distribion_storage \
> meta master-max="1" master-node-max="1" clone-max="2"
> clone-node-max="1" notify="true"
> ms ms_drbd_vni_storage p_drbd_vni_storage \
> meta master-max="1" master-node-max="1" clone-max="2"
> clone-node-max="1" notify="true" is-managed="true" target-role="Started"
> ms ms_drbd_xen_data1 p_drbd_xen_data1 \
> meta master-max="1" master-node-max="1" clone-max="2"
> clone-node-max="1" notify="true"
> ms ms_drbd_xen_data2 p_drbd_xen_data2 \
> meta master-max="1" master-node-max="1" clone-max="2"
> clone-node-max="1" notify="true"
> clone cl_lsb_nfsserver p_lsb_nfsserver \
> meta target-role="Started"
> clone cl_ping p_ping \
> meta globally-unique="false"
> location l_live_distribion_storage g_nfs_distribion_storage \
> rule $id="l_live_distribion_storage-rule" -inf: not_defined pingd or
> pingd lte 0
> location l_live_vni_storage g_nfs_vni_storage \
> rule $id="l_live_vni_storage-rule" -inf: not_defined pingd or pingd
> lte 0
> location l_live_xen_data1 g_nfs_xen_data1 \
> rule $id="l_live_xen_data1-rule" -inf: not_defined pingd or pingd lte 0
> location l_live_xen_data2 g_nfs_xen_data2 \
> rule $id="l_live_xen_data2-rule" -inf: not_defined pingd or pingd lte 0
> colocation c_p_fs_distribion_storage_on_ms_drbd_distribion_storage inf:
> g_nfs_distribion_storage ms_drbd_distribion_storage:Master
> colocation c_p_fs_vni_storage_on_ms_drbd_vni_storage inf:
> g_nfs_vni_storage ms_drbd_vni_storage:Master
> colocation c_p_fs_xen_data1_on_ms_drbd_xen_data1 inf: g_nfs_xen_data1
> ms_drbd_xen_data1:Master
> colocation c_p_fs_xen_data2_on_ms_drbd_xen_data2 inf: g_nfs_xen_data2
> ms_drbd_xen_data2:Master
> order o_ms_drbd_distribion_storage_before_p_fs_distribion_storage inf:
> ms_drbd_distribion_storage:promote g_nfs_distribion_storage:start
> order o_ms_drbd_vni_storage_before_p_fs_vni_storage inf:
> ms_drbd_vni_storage:promote g_nfs_vni_storage:start
> order o_ms_drbd_xen_data1_before_p_fs_xen_data1 inf:
> ms_drbd_xen_data1:promote p_exportfs_vni_storage:start
> order o_ms_drbd_xen_data2_before_p_fs_xen_data2 inf:
> ms_drbd_xen_data2:promote g_nfs_xen_data2:start
> property $id="cib-bootstrap-options" \
> dc-version="1.1.6-9971ebba4494012a93c03b40a2c58ec0eb60f50c" \
> cluster-infrastructure="openais" \
> expected-quorum-votes="2" \
> stonith-enabled="false" \
> no-quorum-policy="ignore" \
> last-lrm-refresh="1350405150"
> rsc_defaults $id="rsc-options" \
> resource-stickiness="200"
> ====================
>
> ------------------------------
> ------------------------------
>
> Now on to the issue I'm experiencing. I have a particular client machine
> that mounts /data/vni-storage via NFS for its apache root directory
> (/var/www). If I log into the server and do an "ls /var/www", I'll see
> the files. I then manually force a resource migration ("crm resource
> migrate g_nfs_vni_storage storage2"). The resource will migrate
> successfully on the back end (as shown by crm status), and everything
> seems fine. However, if I issue an "ls /var/www" again on the client, it
> will basically hang and not properly "see" the share at its new
> location. If I wait long enough (usually a matter of minutes), it will
> sometimes eventually spit on an I/O error message. I've even had
> instances (without my intervention) where the ocf:heartbeat:exportfs
> resource would time out (according to the logs) and "re-export" itself.
> If I log into the server, it will still show everything running fine,
> but on the client, it will now be showing a "stale NFS handle" error
> message.
>
> I've done research to try to understand the issue, and some have
> commented on the fsid parameter needing to match between the cluster
> servers. In fact, I've had that parameter set in the options for
> p_exportfs_vni_storage since the initial deployment about six months ago.
>
> I then had an issue the other day where I had to manually migrate the
> share to the other server, which ultimately led to issues with some of
> the OTHER NFS shares (namely g_nfs_xen_data1). This was a bad share to
> have trouble with, as it is an NFS storage repository for our XenServer
> VM guests, which led to all sorts of "disk failure" issues on the guests.
>
> After looking around some more today, my first thought was that multiple
> NFS shares might not be well supported (even though I really need them
> to be this way). I took a look at the resource script for exportfs
> (/usr/lib/ocf/resource.d/heartbeat/exportfs), and I noticed that when
> the script makes a copy of /var/lib/nfs/rmtab in the backup_rmtab
> function, it filters out any shares that don't match the exported
> directory of the active resource. It looks like this may become a
> problem when the restore_rmtab function is later called after a resource
> migration, because now /var/lib/nfs/rmtab will only contain the
> directory for the active resource and not the other three NFS mounts.
> Maybe this leads to the failover issue?
>
>
> So to sum it up:
>
> Was ocf:heartbeat:exportfs intended to work with multiple, separate NFS
> shares? Due to the way that the rmtab file is backed up, it doesn't seem
> like that is the case. If so, what would be the recommended course of
> action? If I manage the exportfs shares outside of pacemaker, I still
> have to worry about keeping /var/lib/nfs/rmtab copied over on the shares.
>
> In regards to the client getting the "stale NFS handle" error and having
> trouble failing over, is this in any way related to Apache keeping a lot
> of files open on that share (primarily log files)? Would that affect the
> ability for the NFS client to try to "reconnect" to the new server?
>
> Are there any other obviously mistakes or improvements to my pacemaker
> config that could be made?
>
> Thanks.
>
>
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