0 Replies Latest reply on Dec 17, 2012 10:50 PM by 980388

    Best practice for exporting the same disk to multiple guests?

      I've got a T4-4 with two service domains. Each service domain has access to the same pool of SAN disks.

      primary service domain has vds primary-vds0
      secondary service domain has vds secondary-vds0

      So far I've sucessfully built a single backend service for each SAN disk on each service domain and used the MP group operation to enable multipathing, i.e.
      ldm add-vds primary-vds0_a primary
      ldm add-vds secondary-vds0 secondary
      ldm add-vdsdev mpgroup=target1 /dev/dsk/c0t6target1 target1@primary-vds0
      ldm add-vdsdev mpgroup=target1 /dev/dsk/c0t6target1 target1@secondary-vds0
      ldm add-vdisk id=0 bootdisk target1@primary-vds0 guest_a

      Now, I have database datafile LUNS that I need to present to two guests at once since they're using Veritas clustering. As I understand it, what I have to present to each guest is a unique volume (volume@vds) export, and I can do it one of two ways:

      Build mutiple exports of the same disk on the same vds:
      ldm add-vds primary-vds0_a primary
      ldm add-vds secondary-vds0 secondary
      ldm add-vdsdev mpgroup=db1a /dev/dsk/c0c6target5 db1_server_a@primary-vds0
      ldm add-vdsdev mpgroup=db1a /dev/dsk/c0c6target5 db1_server_a@secondary-vds0
      ldm add-vdsdev mpgroup=db1b /dev/dsk/c0c6target5 db1_server_b@primary-vds0
      ldm add-vdsdev mpgroup=db1b /dev/dsk/c0c6target5 db1_server_b@secondary-vds0
      ldm add-vdisk id=6 database_disk db1_server_a@primary-vds0 guest_a
      ldm add-vdisk id=6 database_disk db1_server_b@primary-vds0 guest_b

      Build a separate vds for each guest domain, and then add the vdsdevs to each vds:
      ldm add-vds primary-vds-server_a primary
      ldm add-vds primary-vds-server_b primary
      ldm add-vds secondary-vds-server_a secondary
      ldm add-vds secondary-vds-server_b secondary
      ldm add-vdsdev mpgroup=db1a /dev/dsk/c0c6target5 db_disk@primary-vds-server_a
      ldm add-vdsdev mpgroup=db1a /dev/dsk/c0c6target5 db_disk@secondary-vds-server_a
      ldm add-vdsdev mpgroup=db1b /dev/dsk/c0c6target5 db_disk@primary-vds-server_b
      ldm add-vdsdev mpgroup=db1b /dev/dsk/c0c6target5 db_disk@secondary-vds-server_b
      ldm add-vdisk id=6 database_disk db_disk@primary-vds-server_a guest_a
      ldm add-vdisk id=6 database_disk db_disk@primary-vds-server_b guest_b

      The end result is the same, but is there any advantage (performance, configuration management, whatever) to doing it one way versus the other?

      Tim Metzinger