Veritas Cluster Server (VCS) 7.4.2.x CVMVolDg Agent includes new ScanDisks attribute to refresh VxVM and DMP attributes prior to importing hardware clone and replicated type disk groups

Problem

Veritas Cluster Server (VCS) provides multiple replication agents to manage hardware replication functionality

Veritas has enhanced the VCS 7.4.2.x CVMVolDg Agent by adding a new resource attribute called "ScanDisks".

The new "ScanDisks = 1" CVMVolDg resource attribute will empower the VCS framework to refresh VxVM and DMP attributes prior to importing hardware clone & replicate type disk groups.

• Prior to importing any hardware replicated or hardware clone device managed by Veritas Volume Manger, it is vital the VxVM disk attributes are refreshed using vxdisk scandisks [device=<paths>]

Figure 1 . Different Lunclasses

Error Message

Example: EMC SRDF

1.] Even though the EMC SRDF-R2 (target) disks have been "SPLIT" using EMC SYMCLI command:

# symrdf -g <EMC Device Group> split

2.] The VxVM disk group (i.e. SRDFDG) operation still fails for the EMC SRDF-R2 "SPLIT" disks:

# vxdg -c -o usereplicatedev=only import SRDFDG
VxVM vxdg ERROR V-5-1-19179 Disk group SRDFDG: import failed:
Device is a hardware mirror

3.] DMP & VxVM extended attributes refreshed

# vxdisk scandisks

4.] The VxVM disk group operation now works


The new vxdg "-o usereplicatedev=only" functionality is available with the following Veritas Volume Manager hot-fixes:
 

Linux:

vm-rhel7_x86_64-HotFix-7.4.2.2902.tar.gz
vm-rhel8_x86_64-HotFix-7.4.2.2902.tar.gz
vm-sles12_x86_64-HotFix-7.4.2.2902.tar.gz    
vm-sles15_x86_64-HotFix-7.4.2.2902.tar.gz    

The enhanced functionality is not included in the latest VxVM 7.4.2.3200 public patch. Hot-fixes will be created on top of the Linux related 7.4.2.32xx branch.

Solaris:

vm-sol11_sparc-HotFix-7.4.2.2901.tar.gz    

AIX:

vm-aix-HotFix-7.4.2.2601.tar.gz    

Please contact Veritas Technical Support if you require the above VxVM hot-fixes.

Cause

Some existing VCS replication agents (EMC SRDF, EMC MirrorView, Hitachi TrueCopy) already have additional intelligence built-in to perform selective device rescanning (vxdisk scandisks [device=<paths>]) following replication takeover

The VCS DiskGroup & CVMVolDg resources require “ClearClone = 1” to be defined for importing hardware replicated devices (vxdg -c import).
 

Solution

Veritas Cluster Server (VCS) handling of Hardware Clone & Replicated devices

DMP & VxVM Attributes

To increase the flexibility of managing future hardware technologies

The VCS CVMVolDg agent will be taking over the responsibility of running the selective device scan (vxdisk scandisks device=<paths>) operations for replication agents which don’t have this capability.

VCS CVMVolDg Example
 

group srdf_SG (
        SystemList = { node1 = 0, node2 = 1 }
        AutoFailOver = 0
        Parallel = 1
        AutoStartList = { node1, node2 }
        )

        CFSMount data_cfs (
                Critical = 0
                MountPoint = "/data"
                BlockDevice = "/dev/vx/dsk/LINUXSRDF/data"
                MountOpt = rw
                )

        CFSMount scripts_cfs (
                Critical = 0
                MountPoint = "/data/scripts"
                BlockDevice = "/dev/vx/dsk/LINUXSRDF/scripts"
                MountOpt = rw
                )

        CVMVolDg srdf_dg (
                CVMDiskGroup = LINUXSRDF
                CVMVolume = { data, scripts }
                CVMActivation = sw
                CVMDeportOnOffline = 1
                ClearClone = 1
                DGOptions = { "-t -o usereplicatedev=only" }
                ScanDisks = 1
                )

        requires group cvm online local firm
        data_cfs requires srdf_dg
        scripts_cfs requires data_cfs
        scripts_cfs requires srdf_dg

NOTE: A selective device scan is performed on all paths associated with the disk group name specified when “ScanDisks = 1”.

VCS DiskGroup agent performing selective device scans (example)
 

Figure 2 . Enhanced VCS design

Sample main.cf
 

group srdf_SG (
        SystemList = { node1 = 0, node2 = 1 }
        ClusterList = { clust1 = 0, clust2 = 1 }
        Authority = 1
        AutoStartList = { node1, node2 }
        )

        DiskGroup srdf_sg (
                DiskGroup = LINUXSRDF
                ClearClone = 1
                DGOptions = "-o usereplicatedev=only"
                ScanDisks = 1
                )

        Mount data (
                MountPoint = "/data"
                BlockDevice = "/dev/vx/dsk/LINUXSRDF/data"
                FSType = vxfs
                FsckOpt = "-n"
                )

        Mount scripts (
                MountPoint = "/data/scripts"
                BlockDevice = "/dev/vx/dsk/LINUXSRDF/scripts"
                FSType = vxfs
                FsckOpt = "-n"
                )

        SRDF srdflin (
                GrpName = LINUXSRDF
                )

        data requires srdf_dg
        scripts requires data
        scripts requires srdf_dg
        srdf_dg requires srdflin
 

VRTScavf

Please contact Veritas Technical Support if you require the latest hot-fixes for the VRTScavf package for CVMVolDg.

RHEL8, SLES12, SLES15, AIX & Solaris fixed will be available soon for VRTScavf.