Quick review on what is new in VxSF 6.0 compared to Old releases

Creating a volume of maximum size

In previous releases, Veritas Volume Manager provided a two-step approach to creating a volume of the maximum size. You had to run the vxassist max size command to find the maximum size of the volume to be created with the given constraints. Then, you had to run the vxassist make command and specify the volume size as the maximum determined by the “vxassist maxsize” command

In this release, you can create a maximum sized volume with a single command. Specify the “vxassist make” command with the maxsize keyword.

The vxassist command creates the maximum sized volume possible, taking into consideration any other allocation attributes that you specify.

Veritas Volume Manager co-existence with Oracle Automatic Storage Management (ASM) disks:

ASMdisks are the disks used by Oracle Automatic Storage Management software.  Veritas Volume Manager (VxVM) co-exists with OracleASMdisks, by recognizing the disks as the type Oracle ASM. VxVM protects ASM disks from any operations that may overwrite the disk. VxVM classifies and displays the ASM disks as ASM format disks.

You cannot initialize anASMdisk, or perform any VxVM operations that may overwrite the disk Full Story

Sample VCS configuration file for single Oracle instance Review the sample configuration with a resource of type Oracle that is configured as follows in main.cf file.

The shared disk groups and volumes in the cluster are configured as resources of type DiskGroup and Volume respectively. The volumes are mounted using the Mount agent. The virtual IP address for the service group is configured using the IP and NIC resource types. The Oracle server can be started after each of these resources is brought online.

Note: If your configuration does not use Veritas Volume Manager, use the DiskReservation resource type to configure shared storage instead of the DiskGroup and Volume resource types

Below procedure explains you about ‘ booting from an alternate boot disk’

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To replace disk for a failed boot disk must have at least as much storage capacity as was in use on the disk being replace. It must be large enough to accommodate all subdisks of the original disk at their current disk offsets

# vxprint -g rtdg -st -e ‘sd_disk=”rtdg01″‘

Disk group: rtdg

SD NAME PLEX DISK DISKOFFS LENGTH [COL/]OFF DEVICE MODE

…

sd rtdg01-01 swapvol-01 rtdg01 0 1045296 0 c0t0d0 ENA

sd rtdg01-02 rootvol-01 rtdg01 1045296 16751952 0 c0t0d0 ENA

From the output, add the DISKOFFS and LENGTH values for the last subdisk listed for the disk. This size is in 512 byte sectors. Divide this number by 2 for the size in KB. Full Story

VCS uses two components, LLT and GAB, to share data over private networks among systems. These components provide the performance and reliability that VCS requires.

LLT (Low Latency Transport) provides fast, kernel-to-kernel communications, and monitors network connections.

LLT configuration files are as follows:

/etc/llthosts—lists all the nodes in the cluster
/etc/llttab—describes the local system’s private network links to the other nodes in the cluster
GAB (Group Membership and Atomic Broadcast) provides the global message order that is required to maintain a synchronized state among the nodes. It monitors disk communications such as the VCS heartbeat utility. The /etc/gabtab file is the GAB configuration file.

LLT and GAB initialization configuration files include:

/etc/default/llt
/etc/default/gab Full Story

If I/O errors are intermittent rather than persistent, VxVM sets the failing flag on a disk, rather than detaching the disk. Such errors can occur due to the temporary removal of a cable, controller faults, a partially faulty LUN in a disk array, or a disk with a few bad sectors or tracks.

If the hardware fault is not with the disk itself ( e.g. controller problem), you can use the vxedit command to unset the “failing” flag after correcting the course of the I/O error. Full Story