Disks in Cluster

Question

Hi,
I�m new in Sun Cluster and I have some doubts.
How the custer works with shared disks?
The shared disk can be accessed by the all nodes at same time? Or the shared disk is opened to one node at a time?
I need to use a volume manager like Veritas or I can use a normal filesystem (ufs)?
Thank�s
Paulo Vilhena

Answer 1

Hi Phaulo,
well, the Sun cluster takes care of this, you have to define a storage resource and the cluster will switch over this resource group and make certain at time only one of the nodes will have access to this disks.
Our usual configuration is two DS each with a node and SAN, both nodes having two SAN connections one to each of the SANs in both DCs the disk are then mirrored from the two SANs with SLVM.
I have added the commands we use to set this up below, there are cetainly other ways, but it should help as a starting point.
Assumptions:
- you are using SLVM (aka Disk Suite)
- the two disks have the dids 5 and 9 (as shown by didadm -l)
- the nodes are named mynodep and mynodez
- the resour group mysrvc_rg is defined
- the disks are added to this resource group
- the service name is mysrvc
You have to execute the following commands only on one node except stated otherwise
Create the metadevices (the last metainit gives a warning which you can ignore safely as we not yet have any data the disks)
metaset -s mysrvcds -a -h mynodep mynodez
metaset -s mysrvcds -a -m mynodep mynodez
metaset -s mysrvcds -a /dev/did/rdsk/d5 /dev/did/rdsk/d9
metainit -s mysrvcds d101 1 1 /dev/did/rdsk/d5s0
metainit -s mysrvcds d102 1 1 /dev/did/rdsk/d9s0
metainit -s mysrvcds d100 -m d101 d102
create a file system
-> newfs /dev/md/mysrvcds/rdsk/d100 edit /etc/vfstab on __BOTH__ Nodes and add the following line:
/dev/md/mysrvcds/dsk/d100  /dev/md/mysrvcds/rdsk/d100 /global/mysrvc ufs   2   yes   global,logging
create the Mount points on __BOTH__ Nodes
mkdir /global/mysrvc mount the disks on the Primary Node
mount /global/mysrvc Register the HAStoragePlus Data Service:
scrgadm  -a -t SUNW.HAStoragePlus
create the storage Ressource
scrgadm -a -j mysrvc_storage -g mysrvc_rg -t SUNW.HAStoragePlus -x FilesystemMountpoints=/global/mysrvc -x AffinityOn=true some output to show the resulting configuration:
root@mynodep:~ # metaset
Set name = mysrvcds, Set number = 1
Host                Owner
  mynodep            Yes
  mynodez
Mediator Host(s)    Aliases
  mynodep
  mynodez
Driv Dbase
d5   Yes
d9   Yes
root@mynodep:~ # metastat -s mysrvcds
mysrvcds/d100: Mirror
    Submirror 0: mysrvcds/d101
      State: Okay
    Submirror 1: mysrvcds/d102
      State: Okay
    Pass: 1
    Read option: roundrobin (default)
    Write option: parallel (default)
    Size: 106583040 blocks (50 GB)
mysrvcds/d101: Submirror of mysrvcds/d100
    State: Okay
    Size: 106583040 blocks (50 GB)
    Stripe 0:
        Device   Start Block  Dbase        State Reloc Hot Spare
        d5s0            0     No            Okay   No
mysrvcds/d102: Submirror of mysrvcds/d100
    State: Okay
    Size: 106583040 blocks (50 GB)
    Stripe 0:
        Device   Start Block  Dbase        State Reloc Hot Spare
        d9s0            0     No            Okay   No
Device Relocation Information:
Device   Reloc  Device ID
d9   No         -
d5   No         -
root@mynodep:~ # scstat -D
-- Device Group Servers --
                         Device Group        Primary             Secondary
  Device group servers:  mysrvcds            mynodep             mynodez
-- Device Group Status --
                              Device Group        Status
  Device group status:        mysrvcds            Online
-- Multi-owner Device Groups --
                              Device Group        Online Status
root@mynodep:~ #