5.4. Compute Node Disk Partitioning

5.4.1. Default Disk Partitioning

The default root partition is setup to be 6 GB. The default swap partition is 1 GB. The remainder of the root disk is setup as the partition /state/partition1.

All remaining disk drives will have one partition with the name /state/partition2, /state/partition3, ...

For example, the following table describes the default partitioning for a compute node with 3 SCSI drives.

After the initial installation, all data in the file systems labeled /state/partitionX will be preserved over reinstallations.

5.4.2. How to Change the Size of Root and Swap Partitions on Compute Nodes

This section describes a simple method in which to change the size of the default root and swap partitions on compute nodes. If more control over the compute partitioning is desired, see the section Customizing Compute Node Disk Partitions.

First, create the file extend-auto-partition.xml.

# cd /home/install/site-profiles/4.0.0/nodes/
# cp skeleton.xml extend-auto-partition.xml

Above the <main> section, insert the following two lines:

<var name="Kickstart_PartsizeRoot" val="10000"/>
<var name="Kickstart_PartsizeSwap" val="2000"/>

This will increase the root partition from the default 6 GB to 10 GB and it will increase the swap partition from the default 1 GB to 2 GB.

Then apply this configuration to the distribution by executing:

# cd /home/install
# rocks-dist dist

To reformat all the compute nodes to your specification above, execute:

# ssh-add
# cluster-fork 'rm /.rocks-release'
# cluster-fork '/boot/kickstart/cluster-kickstart'

5.4.3. Customizing Compute Node Disk Partitions

Create a new XML configuration file that will replace the current auto-partition.xml configuration file:

# cd /home/install/site-profiles/4.0.0/nodes/
# cp skeleton.xml replace-auto-partition.xml

Inside replace-auto-partition.xml, add the following section:

<main>
	<part> / --size 4096 --ondisk hda </part>
	<part> swap --size 1000 --ondisk hda </part>
	<part> /mydata --size 1 --grow --ondisk hda </part>
</main>

This will set up a 4 GB root partition, a 1 GB swap partition, and the remainder of the drive will be set up as /mydata. Additional drives on your compute nodes can be setup in a similar manner by changing the --ondisk parameter.

In the above example (aside from the <part> and </part> tags), the remaining syntax follows directly from Red Hat's kickstart. For more information on the part and the clearpart keywords, see Red Hat Enterprise Linux 3: System Administration Guide

User-specified partition mountpoint names (e.g., /mydata) cannot be longer than 15 characters.

If you would like to use software RAID on your compute nodes, inside replace-auto-partition.xml add section that looks like:

<main>
	<part> / --size 8000 --ondisk hda </part>
	<part> swap --size 1000 --ondisk hda </part>

	<part> raid.00 --size=10000 --ondisk hda </part>
	<part> raid.01 --size=10000 --ondisk hdb </part>

	<raid> /mydata --level=1 --device=md0 raid.00 raid.01 </raid>
</main>

If the user-specified partitioning scheme is not currently configured on an installing compute node, then all the partitions on the compute node will be removed and the user-specified partitioning scheme will be forced onto the node.

If the user-specified partitioning scheme is currently configured on an installing compute node, then all the partitions on the node will remain intact and only the root partition will be reformatted.

If you want to change the size of an existing partition, you must rename the mountpoint for the partition. This is because the matching logic we wrote only keys off mountpoint names.

If you change the partitioning scheme, all partitions will be removed and reformatted. This is because we have been unable to make Red Hat's clearpart --drives= work as advertised.

Then apply this configuration to the distribution by executing:

# cd /home/install
# rocks-dist dist

To reformat all the compute nodes to your specification above, execute:

# ssh-add
# cluster-fork 'rm /.rocks-release'
# cluster-fork '/boot/kickstart/cluster-kickstart'

5.4.4. Forcing the Default Partitioning Scheme on a Compute Node

This procedure describes how to force a compute node back to the default Rocks partitioning scheme regardless of the current state of the disk drive on the compute node. See Default Partitioning for a description of the Rocks compute node default partitioning scheme.

Create a new XML configuration file that will replace the current auto-partition.xml configuration file:

# cd /home/install/site-profiles/4.0.0/nodes/
# cp skeleton.xml replace-auto-partition.xml

Inside replace-auto-partition.xml, add the following section:

<main>
	<part> force-default </part>
</main>

Then apply this configuration to the distribution by executing:

# cd /home/install
# rocks-dist dist

To force all the compute nodes back to the Rocks default partitioning scheme, execute:

# ssh-add
# cluster-fork 'rm /.rocks-release'
# cluster-fork '/boot/kickstart/cluster-kickstart'

After you have returned all the compute nodes to the default partitioning scheme, then you'll want to remove replace-auto-partition.xml in order to allow Rocks to preserve all non-root partition data.

# rm /home/install/site-profiles/4.0.0/nodes/replace-auto-partition.xml

Then apply this update to the distribution by executing:

# cd /home/install
# rocks-dist dist