HP-UX Service Guard Cluster Implementation




HP-UX Serviceguard Cluster : Implementation


QUESTION: 


What are the steps to creating a functional Serviceguard cluster?



NOTE: "Serviceguard does not support communication across routers between nodes in the same cluster."

Steps: 

1.Install the Serviceguard product.
2.NETWORKING Preparation
3.LVM Preparation
4. Building the cluster
5.Creating Package files
6. Package global node switching setup.


1.Install the Serviceguard product.

 

Serviceguard is a licensed product and requires a codeword to install from the Application media.


2.NETWORKING Preparation


/etc/rc.config.d/netconf
Define LANs that will have "stationary" IP addresses. Do NOT define a 0.0.0.0 IP for LAN adapters that will act as a standby LAN for Serviceguard! If this has been done, "unplumb" and then "plumb" the LAN adapter and then remove any reference to the standby LANs from the netconf file:


  # ifconfig lanN unplumb  (where lanN is the standby LAN)
  # ifconfig lanN plumb    (to make it available to standby)


/etc/services and /etc/inetd.conf

Serviceguard commands use network ports for commands that work on the local server or in conjunction with other servers in the cluster (or to be in the cluster). After Serviceguard is loaded, /etc/services should have 9 hacl lines:


hacl-hb     5300/tcp          # High Availability (HA) Cluster heartbeat
  hacl-gs     5301/tcp          # HA Cluster General Services
  hacl-cfg    5302/tcp          # HA Cluster TCP configuration
  hacl-cfg    5302/udp          # HA Cluster UDP configuration
  hacl-probe  5303/tcp          # HA Cluster TCP probe
  hacl-probe  5303/udp          # HA Cluster UDP probe
  hacl-local  5304/tcp          # HA Cluster Commands
  hacl-test   5305/tcp          # HA Cluster Test
  hacl-dlm    5408/tcp          # HA Cluster distributed lock manager


/etc/inetd.conf should have 2:


  hacl-cfg    dgram   udp    wait    root  /usr/lbin/cmclconfd cmclconfd -p
  hacl-cfg    stream  tcp    nowait  root  /usr/lbin/cmclconfd cmclconfd -c


Serviceguard Manager uses this line in /etc/inetd.conf:

  hacl-probe  stream  tcp    nowait  root  /opt/cmom/lbin/cmomd cmomd -f /var/opt/cmom/cmomd.log


Insure these hacl ports are functioning:


  # netstat -a | grep hacl
  tcp        0      0  *.hacl-probe           *.*                     LISTEN
  tcp        0      0  *.hacl-cfg             *.*                     LISTEN
  udp        0      0  *.hacl-cfg             *.*   


If they are not observed, cause inetd to re-read /etc/inetd.conf:

# inetd -c

It may be necessary to 'inetd -k' and restart 'inetd'.

/etc/rc.config.d/netconf

Use the simple hostname of the server when configuring the hostname.

/etc/cmcluster/cmclnodelist
Serviceguard only requires this file before the cluster is built.

Thereafter, internal security mechanisms authenticate cluster commands.

Requirement: Create the file on every node and list ALL NODES in the file, giving them root access, much link a .rhosts file.

Example:


  node_1     root 
  node_2     root


OBSOLETE:.rhosts - though used in past versions of Serviceguard, .rhosts is no longer consulted during Serviceguard operations.

/etc/nsswitch.conf
Hostname lookup begins with this file. Current versions of Serviceguard require hostname lookup look in /etc/hosts before looking to DNS. Depending on the version of HPUX, /etc/nsswitch.conf should be configured thus:


  11iv1:  
   hosts:    files   dns

  11iv2 and greater:
   hosts:    files   dns
   ipnodes:  files   


identd

As of October 2004, Serviceguard began using more stringent security when validating the source of Serviceguard commands. All current versions of Serviceguard use the 'identd' daemon delivered with sendmail to perform a Caller-ID-like service that matches hostnames to IPs of any node running Serviceguard commands. 'identd' in sendmail version 8.9.3 works with Serviceguard. The following lines must exist in order for Serviceguard to work with identd.


  11.11:
  /etc/services:
ident        113/tcp  authentication # RFC1413

  /etc/inetd.conf:
ident        stream tcp wait   bin  /usr/lbin/identd   identd

  11.23 and up:
  /etc/services:
auth         113/tcp  authentication # Authentication Service

  /etc/inetd.conf:
auth         stream tcp6 wait   bin  /usr/lbin/identd   identd


NOTE: sendmail need not be activated to enable 'identd'.

/etc/hosts
In conjunction with identd, /etc/hosts file on each node must list every NIC on every server which will need to communicate with a cluster node.

Example:


        15.145.162.131          gryf.uksr.hp.com            gryf
        10.8.0.131              gryf-hb.uksr.hp.com         gryf
        10.8.1.131              gryf-bkup.uksr.hp.com       gryf
        10.8.2.131              gryf-data.uksr.hp.com       gryf
        15.145.162.132          sly.uksr.hp.com             sly
        10.8.0.132              sly-hb.uksr.hp.com          sly
        10.8.1.132              sly-bkup.uksr.hp.com        sly
        10.8.2.132              sly-data.uksr.hp.com        sly
        10.30.8.7               bot.uksr.hp.com             bot # quorum server


Notes:

  1. Every fixed IP must be identified in the /etc/hosts file.
    Serviceguard can use any NIC for internode communication.
  2. Use the fully-qualified domain name first, to avoid warning messages from Serviceguard, "Warning, Unable to determine local domain name..."
  3. The simply hostname must be applied to every line in order to match the IP to the hostname. This does not interfere with normal hostname look operations.

/var/adm/inetd.sec

This security file filters messages considered by inetd. It is not normally configured but if the Admin wishes to do so, insure Serviceguard ports are allowed to pass messages through specific IPs.

Example inetd.sec content:


  ident     allow   127.0.0.1 
  hacl-cfg  allow   127.0.0.1  
      - allows a range of servers to contact the hacl-cfg utility


Examples:


   hacl-cfg  allow 127.0.0.1 alvin simon theodore (all cluster nodes)
   hacl-cfg  allow 127.0.0.1 15.*


NOTES:

  1. ident refers to identd, integrated into Serviceguard since Oct 2004.
  2. 127.0.0.1 is required for Serviceguard configuration.
  3. When used with no options, cmquerycl probes port 5302 on all nodes on the heartbeat network to learn of cluster capability.

3.LVM Preparation

 

On one server, create the volume groups, logical volumes and mount point directories for the application that will be "packaged".

This example assumes a 4-disk VG, each having two channels connecting to each node. Example commands use the fictitious volume group name vg_data.

Note that the paths to the shared disks may have different dsk identifiers on each server.


                         Storage Array
           c0     +--------------------------+     c2
          --------+ (disk t1d0)  (disk t2d0) +---------
    Node_1        |                          |         Node_2
          --------+ (disk t3d0)  (disk t4d0) +---------      
           c1     +--------------------------+     c3


The intent of this example is to create Physical Volume Groups in order to force mirroring across PVlinks. The disks at cXt1d0 and cXt2d0 will be one PVG, while t3 and t4 the other. Where possible, load balancing will also be incorporated.


  # pvcreate -f /dev/rdsk/c0t1d0   (repeat for other disks)
  # mkdir /dev/vgdata 
  # mknod /dev/vgdata/group c 64 0xNN0000  - where NN = unique number
  # vgcreate -g PVG0 vg_data /dev/dsk/c0t1d0 /dev/dsk/c0t2d0 
  # vgextend -g PVG1 vg_data /dev/dsk/c1t3d0 /dev/dsk/c1t4d0 
  # vgextend  vg_data /dev/dsk/c1t1d0 /dev/dsk/c1t2d0 
  # vgextend  vg_data /dev/dsk/c0t3d0 /dev/dsk/c0t4d0 
  # lvcreate -L 17179 -s g /dev/vg_data   (PVG-strict allocation)
  # lvextend -m 1 /dev/vg_data/lvol1 PVG1 


In the example, node_1's /etc/lvmtab would look like this:


vg_data
/dev/dsk/c0t1d0  (pri-path t1 - PVG0)
/dev/dsk/c0t2d0  (pri-path t2 - PVG0)
/dev/dsk/c1t3d0  (pri-path t3 - PVG1)
/dev/dsk/c1t4d0  (pri-path t4 - PVG1)
/dev/dsk/c1t1d0  (alt-path t1 - PVG0)
/dev/dsk/c1t2d0  (alt-path t2 - PVG0)
/dev/dsk/c0t3d0  (alt-path t3 - PVG1)
/dev/dsk/c0t4d0  (alt-path t4 - PVG1)


And node_1's /etc/lvmpvg would look like this:


VG /dev/vg_data
PVG PVG0
/dev/dsk/c0t1d0
/dev/dsk/c0t2d0
PVG PVG1
/dev/dsk/c1t3d0
/dev/dsk/c1t4d0

 # vgchange -a y vg_data
 # newfs -F vxfs /dev/vg_data/lvol1
 # mkdir /data1
 # mount /dev/vg_data/lvol1 /data1


Repeat this process for every volume group managed by a Serviceguard package.

It is recommended that all VG manipulation be performed on the server maintaining the /etc/lvmpvg file. If that is not desired, create the /etc/lvmpvg on each node that will be used to manage the LVM VGs for the packages. Insure the correct dsk pathing is specificed.

Insure the application runs and can utilize the file systems that will be governed by a Serviceguard package. Then unmount the logical volumes and deactivate the volume groups in which they reside.


3.A Importing the VG into the other nodes

 

Any server that will adopt a package must reference that packages' LVM volume groups in the /etc/lvmtab file. Use strings /etc/lvmtab to determine the volume groups and their special files.

Import the volume groups that will be managed by Serviceguard using this procedure:


  # vgexport -pvs -m map.vg_data /dev/vg_data 
  # rcp map.vg_data :/etc/lvmconf/


Repeat for other volume groups and servers as needed.

Create a listing of /dev/vg_data/group files that shows the minor number used.


  # ll /dev/vg*/group | awk '{print $6,$10}' >/tmp/group_list


On the other servers that will adopt the package and it's volume groups:


  # mkdir /dev/vg_data ; cd /dev/vg_data 
  # mknod group c 64 0xNN0000  
      NN = Match the group minor number listed in /tmp/group_list!
  # vgimport -vs -m /etc/lvmconf/map.vg_data /dev/vg_data

  # mkdir /data1
  # mount /dev/vg_data/lvol1 /data1


Repeat as needed for every volume group to be managed by Serviceguard.

Consecutively on each server that will adopt the package, create the mount points, activate the volume group, mount the file systems for the application and run the application on the adoptive server to verify it works before expecting Serviceguard to do the same.

/etc/lvmrc
 

Normally, one would want all VGs to be activated at boot time. In a Serviceguard node, only private VGs should be activated at startup. Attempts to activate "clustered" VGs at boot time will generate error messages to the console. To prevent the attempt and subsequent messages, edit /etc/lvmrc - change AUTO_VG_ACTIVATE=0.

Under the section titled custom_vg_activation() add private volume groups (other than vg00) that Serviceguard will not be managing:


     /sbin/vgchange -a y -s vg06 vg07 
     parallel_vg_sync "/dev/vg06 /dev/vg07"  


/etc/fstab
 

Do not list the lvol/mount pair of any file system that Serviceguard will manage in the /etc/fstab file. The administrator will load the package control script will this information later.


4. Building the cluster


Creating the Cluster configuration file.

For the purposes of this example, the cluster configuration file will be called "CONF". Make Serviceguard discover the nodes that will be used in the cluster, and create a cluster configuration file:

# cd /etc/cmcluster
# cmquerycl -C CONF -n Node_1 -n Node_2 ... 


If using a quorum server, the syntax is:

# cmquerycl -C CONF -n Node_1 -n Node_2 ... -q (qs_hostname) 


The CONF file should be created, listing both nodes, a cluster lock disk VG (automatically selected by Serviceguard), sections describing the LANs on each node, cluster parameters and finally the volume groups each node has in common.

  • Set the NODE_TIMEOUT to 8 seconds (8000000).
  • Configure MAX_CONFIGURED_PACKAGES to at least the number of packages that the cluster will run.
  • If there are multiple active LANs between nodes, change theSTATIONARY_IP name to HEARTBEAT_IP to induce redundant heartbeat transmission.
  • Insure all of the volume groups common to the cluster nodes' lvmtab files are listed at the bottom of the file.

If satisfied, check the file:


  # vgchange -a y (vg_lock)
  # cmcheckconf -C CONF


If this succeeds, proceed to create the cluster binary file:


  # cmapplyconf -C CONF
  # vgchange -a n (vg_lock)


The initial cmapplyconf performs the following 4 tasks:

  • cmcheckconf (again)
  • Build and distribute the cluster binary file, cmclconfig, to each cluster node.
  • Install the cluster lock structure on the designated disk.
  • Load the cluster ID into each of the common VG disks to require them to be activated in "exclusive" mode.

Now, with the cluster binary distributed, a packageless cluster can be started:

# cmruncl 

NOTES:

  1. Even with no packages, a Serviceguard cluster can perform standby LAN failover.
  2. "Clustered" VGs will no longer activate using the "vgchange -a y" method.
    "cmlvmd" must be active to authorize clustered VG activation using the "vgchange -a e" method. cmlvmd must be active to install an 'exclusive' or 'shared' activation mode on cluster-intended a volume group.
  3. If a clustered volume group will be used for SGeRAC (Serviceguard extension for Real Applications Clusters (Oracle), the VG's activation mode must be changed from "exclusive" to "shared" in order that multiple nodes can activate it concurrently.

The procedure is:

# vgchange -c n
# vgchange -c y -S y

Such VGs should only be activated for RAW access. Co-mounted file systems will cause system panics if any file system structure is modified. VGs configured to activate in 'shared' mode cannot be modified by LVM commands. (Note man page warning).


5. Creating the package files

 

Create a directory for each package:


 cmcluster# mkdir orapkg  (example name)
 cmcluster# cd orapkg     (example name)
 orapkg#


In the package directory, build the package configuration file, and the package control script:


orapkg# cmmakepkg -p config     (example pkg config file name)
orapkg# cmmakepkg -s control.sh (example pkg control file name)


Edit the package configuration file, adding or setting the package-specific parameters (which are described in the file).

NOTES:

  • The following is an example of what might be used in each line.
  • the preferred default settings are listed first.
  • - "|" = "or"


PACKAGE_NAME                  (user-defined name)
PACKAGE_TYPE                  FAILOVER | SYSTEM_MULTI_NODE
   NOTE: SYSTEM_MULTI_NODE packages are only supported with HP CVM and CFS.

FAILOVER_POLICY               CONFIGURED_NODE | MIN_PACKAGE_NODE
FAILBACK_POLICY               MANUAL | AUTOMATIC

NODE_NAME                     (primary hostname)
NODE_NAME                     (adoptive hostname)
NODE_NAME                     (2nd adoptive hostname - if any)

AUTO_RUN                                  YES | NO
LOCAL_LAN_FAILOVER_ALLOWED    YES | NO
NODE_FAIL_FAST_ENABLED            NO  | YES

RUN_SCRIPT                    /etc/cmcluster/orapkg/control.sh 
RUN_SCRIPT_TIMEOUT            600  (in seconds)
HALT_SCRIPT                   /etc/cmcluster/orapkg/control.sh
HALT_SCRIPT_TIMEOUT           600  (in seconds)

SERVICE_NAME                  ora_mon (referenced in control.sh too)
SERVICE_FAIL_FAST_ENABLED     NO
SERVICE_HALT_TIMEOUT          100  (in seconds)

SUBNET                        15.44.48.0   (if pkg relies on a LAN NIC)


NOTE: The Admin can configure the Serviceguard package to trigger a package failover on thresholds or up/down state of system hardware and software resources:


#RESOURCE_NAME               /vg/vg00/pv_summary
#RESOURCE_POLLING_INTERVAL   10
#RESOURCE_START              AUTOMATIC
#RESOURCE_UP_VALUE           = UP
#RESOURCE_UP_VALUE           = PVG_UP


Edit the package control script. Reference the package-specific resources that the package will activate when started. The following are example resource definition lines from a package control script:

VGCHANGE="vgchange -a e"

Note: for SGeRAC 'shared' VGs, use this mode instead:

VGCHANGE="vgchange -a s"


CVM_ACTIVATION_CMD="vxdg -g \$DiskGroup set activation=exclusivewrite"

VG[0]=""      Example.  Add more VGs as needed

LV[0]="/dev/vg01/lvol1"; FS[0]="/log1"; FS_MOUNT_OPT[0]="-o rw"
LV[1]="/dev/vg01/lvol2"; FS[1]="/log2"; FS_MOUNT_OPT[1]="-o rw"
LV[2]="/dev/vg01/lvol3"; FS[2]="/log3"; FS_MOUNT_OPT[2]="-o rw"
   +   |-------------|      +   |---|                +    \\\\\
user-defined values


+ The index number must be a continuous sequence - no gaps!
\\\ The "-o largefiles" mount option is legitimate if the file system has been created thus.


FS_UMOUNT_COUNT=1  increment this value of the application needs more time
                   to release file systems.

FS_MOUNT_RETRY_COUNT=0

IP[0]="15.44.49.77"          (sample relocatable IP)
SUBNET[0]="15.44.48.0"       (matching subnet for relocatable IP)

SERVICE_NAME[0]="ora_mon"
SERVICE_CMD[0]="/etc/cmcluster/orapkg/control.sh monitor"
SERVICE_RESTART[0]="-r 1"    (restart attempts)


Add custom commands to customer_defined_run_cmds and customer_defined_halt_cmds sections as needed.

With the package configuration and control files customized, copy the control script to the adoptive nodes so that they too can run the package.


 # rcp -pr /etc/cmcluster/orapkg  (node_2):/etc/cmcluster/


Once complete, perform a check of the files:

orapkg# cmcheckconf -P config
 

If the command succeeds without error, add the package to the cluster binary:

orapkg# cmapplyconf -P config
 

Use cmviewcl to view the state of the package:

# cmviewcl -v -p orapkg
 

Add packages as needed.


6. Package global and node switching

 

Serviceguard packages can be enabled or disabled to run on the cluster or specific nodes in the cluster. Observe this cmviewcl output:

# cmviewcl -v -p clk


UNOWNED_PACKAGES

    PACKAGE      STATUS       STATE        AUTO_RUN     NODE
    clk          down         halted       disabled     unowned

      Policy_Parameters:
      POLICY_NAME     CONFIGURED_VALUE
      Failover        configured_node
      Failback        manual

      Script_Parameters:
      ITEM       STATUS   NODE_NAME    NAME
      Subnet     up       eon          16.113.0.0
      Subnet     up       ion          16.113.0.0

      Node_Switching_Parameters:
      NODE_TYPE    STATUS       SWITCHING    NAME
        Primary      up           enabled      eon
        Alternate    up           disabled     ion



The cmmodpkg command enables or disables switching flags.

Compare AUTO_RUN (global switching) to a master circuit breaker and Node_switching to room-based circuit breakers.

To enable the master (AUTO_RUN) breaker such that the package is allowed to run, use this command:

# cmmodpkg -e 


To enable a specific node to run the specified package, use this form of the cmmodpkg command:

# cmmodpkg -e -n 


NOTES:

  1. When the "primary" node is enabled to run a package and that package has been enabled to run, the package auto-start.
  2. Though AUTO_RUN can be initially set in the package configuration file, it is a dynamic flag, changed by the run-ability of the package.


Redirect Server Console to Serial port in Linux

Redirecting the Server Console to the Serial Port Using Linux Operating System:

Although the server’s ILOM has a redirection feature that allows you to do this, you can also redirect the server console to the serial port by doing the following for either Red Hat (RHEL) or Suse (SLES): 


1. Add the following line in /etc/inittab file (for SLES, this line might already exist but be commented out. If so, simply remove the "#" at the beginning of the line): 

s0:12345:respawn:/sbin/agetty -L 9600 ttyS0 vt102
 

2. Add the following line in the /etc/securetty file: 

ttyS0
 

3. Change the /etc/grub.conf file as described below.


a. Comment the line that begins with "splashimage ...", like this: 

# splashimage=(hd0,0)/grub/splash.xpm.gz
 

b. Add console=ttyS0 console=tty0 at the end of the line that starts with ""kernel /vmlinuz ..., for example: 


kernel /vmlinuz-2.6.9 ro root=LABEL=/ debug console=ttyS0,9600 console=tty0
 

c. Optionally, to have the grub boot menu display at the serial console, add the following lines before the splashimage line: 


serial --unit=0 --speed=9600

terminal --timeout=10 serial console

 
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