XVM: eXtended Visualization Mod is a battle interface modification for the popular MMO, World of Tanks. There are over 3 700 000 players using the mod worldwide, with new installations every minute. XVM is a completely free modification with open source code under the GNU GPL v3 license. Recommended XVM versions (stable) If there is no stable version for the current World of Tanks client in the table above, it means work is still in progress. Bekijk het profiel van Manas Maiti op LinkedIn, de grootste professionele community ter wereld. Manas heeft 4 functies op zijn of haar profiel. Bekijk het volledige profiel op LinkedIn om de connecties van Manas en vacatures bij vergelijkbare bedrijven te zien. VxVM, on Solaris 10 for SPARC, has been set up to mirror each disk, ie Array 1 Disk 1 is mirrored to Array 2 Disk 1 etc etc. We had a problem with the power to the controller of array 2 and the disks in that array ended up in a disabled and removed state. The power has now been restored and the disks are now visible to the operating system again.

Let us now see different volume layouts that can be created in veritas volume manager. Before diving deep into the RAID levels first create a Disk group with 4 disks. To do this we have to initialize 4 disks to take them under VxVM control.

After this create the disk group mydg with these four disks by naming them from disk01 through disk04.

To confirm the disk group creation check the disks in the disk group mydg:

Concatenated Volume

As shown in the diagram below, in RAID 0 concat volume data is first written linearly in disk01 and then to disk02. Number of subdisks in a concat volume depends upon the size of the volume. IF you have a volume greater than the size of a physical disk you would have a single sub disk on one physical disk and another sub disk on the next physical disk. Remember that the number of sub disks also depend on other factors too. The disadvantage of concat volume is that, it does not provide any redundancy to the data as we always have only one copy of data at a time. Minimum disks required to create a concat volume is 1. Command to create a concat volume :

To print the layout of myvol :

RAID 0 (striped volume)

In this case we spread the data out to multiple disk by creating equal sized columns on each disk. Each column will be on a separate disk. Similar to concat volume a stripped volume also do not provide any redundancy to the data as it has only one copy of data at any point in time. To create a stripped volume you need atleast2 disks.

Now you can specify how many columns you need to stripe out the data. Also you can mention the stripe unit.

Mirrored layout (RAID 1)

Mirrored layout or RAID 1 layout is one of the most commonly used layout in production environments. RAID 1 simply mirrors all the data from one disk to another so that we have an extra copy of data. This provides us the necessary data redundancy. Here each plex is on a different disk. Command to create a RAID 1 mirrored volume is :

To check the layout of a RAID 1 mirrored volume :

RAID 5

In case of RAID 5 volumes a parity information is stored on every disk as shown in the diagram. Now this parity can be used in case you want to recover the data lost due to a disk failure. The parity is spread across all the disk to ensure that we have sufficient copies of parity all the time. We need atleast 3 disks to create a RAID 5 volume. Command to create a RAID 5 volume is :

To check the layout of a RAID 5 volume :

Advantages and disadvantages of various RAID levels

Mirror-stripe (RAID 1+0)

In case of a stripe mirror the data is first mirrored and then the mirrored data is striped as shown in the diagram. This requires atleast 4 disk. Command to create a mirror-stripe is :

To print the layout of a mirror-stripe volume :

Mirror-concat (RAID 0+1)

Now in case of a mirror-concat volume, the data is first concatenated and then this concatenated data is mirrored as shown in the diagram. This requires atleast 4 disks. To create a mirror-concat volume :

To print the layout of a mirror-concat volume :

Comparisons of various RAID levels

Layered volumes

Layered volumes are actually built on top of other volumes. In layered volumes data is mirrored at sub disk level which brings in more granularity. Now to do this VxVM creates sub volumes from traditional volumes. Advantages 1. Faster recovery from failure than RAID 1+0 and RAID 0+1 2. Can persist more disk failures than RAID 1+0 and RAID 0+1 Disadvantage 1. Requires more VxVM objects ( sub volumes are required for a layered volume)

1. concat-mirror

In case of concat-mirror, sub disks are concatenated to create the plexes for the sub volumes. The sub volumes are the mirrored to create the top level plex and eventually top level volume. Advantage Recovery is faster as each portion of concatenation is mirrored separately Command to create a concat-mirror volume :

Check the layout of the volume we just created. You should see 2 subvolumes with 2 volumes each. Each volume will have one plex with one sub-disk.

2. stripe-mirror

In case of stripe-mirror, sub disks are mirrored to create the plexes for the sub volumes. The sub volumes are then striped to create the top level plex and eventually a top level volume. Advantage More tolerant to faults, as each stripe is mirrored separately. Command to create a stripe-mirror volume :

Vxvm Commands

Check the layout of the volume we just created. You should see 2 subvolumes with 2 volumes each. Each volume will have one plex with one sub-disk.

I hope the post was informative, Do subscribe to stay updated.

How to Create a VxVM Shared-Disk Group for the Oracle RAC Database

Perform this task only if you are using VxVM with the cluster feature.

If you are using VxVM with the cluster feature, VxVM requires a shared-disk group for the Oracle RAC database or ASM to use.

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Before You Begin

Note the following points.

• Ensure that the required Sun Cluster Support for Oracle RAC software packages are installed on each node. For more information, see Installing the Sun Cluster Support for Oracle RAC Packages.

• Do not register the shared-disk group as a cluster device group with the cluster.

• Do not create any file systems in the shared-disk group because only the raw data file uses this disk group.

• Create volumes as the gen use type.

• Disks that you add to the shared-disk group must be directly attached to all the cluster nodes.

• Ensure that your VxVM license is current. If your license expires, the node panics.

1. Use VERITAS commands that are provided for creating a VxVM shared-disk group.

   For information about VxVM shared-disk groups, see your VxVM documentation.

2. If you are using ASM, specify the raw devices that you are using for the ASM disk group. Download myanmar font for mac.

   To specify the devices, modify the ASM_DISKSTRING ASM instance-initialization parameter.

   Forexample, to use the /dev/md/setname/rdsk/d path for the ASM disk group, add the value /dev/md/*/rdsk/d* to the ASM_DISKSTRING parameter. If you are modifying this parameter by editingthe Oracle initialization parameter file, edit the parameter as follows:

   If you are using mirrored devices, specify external redundancy in the ASM configuration.

   For more information, see your Oracle documentation.

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Next Steps

Vxvm Cheat Sheet

Go to Registering and Configuring Storage Resources for Oracle Files.