Out of Sync: Maddy's Blog

One of the questions that our team frequently encounters is regarding the type of scsi reservation Solaris Cluster uses.   This can be determined in a very simple way.  How many nodes does a shared disk connected to?  

 If the shared disk is connected to 2 nodes, then it uses SCSI-2 reservations.  If it is connected to more than 2 it uses SCSI-3 reservations.  Where can you find more details regarding this?   You should be checking out the scdidadm man page.

 bash-3.00# man -M /usr/cluster/man scdidadm
Reformatting page.  Please Wait... done

System Administration Commands                       scdidadm(1M)

NAME
     scdidadm - device identifier configuration  and  administra-
     tion utility wrapper

SYNOPSIS
     /usr/cluster/bin/scdidadm -C

     /usr/cluster/bin/scdidadm -c

     /usr/cluster/bin/scdidadm -F {pathcount | scsi3 | useglobal} instance

     /usr/cluster/bin/scdidadm -G

     /usr/cluster/bin/scdidadm -G {pathcount | prefer3}

     /usr/cluster/bin/scdidadm {-l | -L} [-h] [-o fmt]... [path | instance]

     /usr/cluster/bin/scdidadm -R {path | instance | all}

     /usr/cluster/bin/scdidadm -r

     /usr/cluster/bin/scdidadm -T remote-nodename -e replication-type

     /usr/cluster/bin/scdidadm -t source-instance:destination-instance -e replication-type
     [-g replication-device-group]

     /usr/cluster/bin/scdidadm [-u] [-i]

     /usr/cluster/bin/scdidadm -v
.

.

   pathcount           Determines the fencing  protocol  by
                             the  number  of  DID  paths that are
                             attached to the shared device.

                                 o    For  a  device  that   uses
                                      fewer than three DID paths,
                                      the command sets the SCSI-2
                                      protocol.

                                 o    For  a  device  that   uses
                                      three  or  more  DID paths,
                                      the command sets the SCSI-3
                                      protocol.

         scsi3               Sets the  SCSI-3  protocol.  If  the
                             device  does  not support the SCSI-3
                             protocol, the fencing protocol  set-
                             ting remains unchanged.

To find out the method being used, you can execute the following command:

bash-3.00# scdidadm -G

The cluster is currently configured to use DID path count algorithm to determine fencing protocol for shared devices.

To find the reservations keys on a disk, you should use the scsi command:

For SCSI-2, a sample output from a 2 node cluster:

bash-3.00#  /usr/cluster/lib/sc/pgre -c pgre_inkeys -d /dev/did/rdsk/d3
key[0]=0x47cd37ab00000001.
key[1]=0x47cd37ab00000002.

For SCSI-3, a sample output from a 4 node cluster:

 bash-3.00#  /usr/cluster/lib/sc/scsi -c inkeys -d /dev/did/rdsk/d10s2
Reservation keys(4):
0x47f5da4400000003
0x47f5da4400000001
0x47f5da4400000002
0x47f5da4400000004

WARNING:  Do not administer any of these commands without understanding the implications - do it only on a test cluster lest you're willing to land in trouble!!