Novell Doc: OES 2 SP3: Installation Guide - Using EVMS to Manage Devices

A.4 Using EVMS to Manage Devices

You can use the free space on the system device for NSS or Linux POSIX file systems. Consider the guidelines below when working with EVMS-managed devices.

A.4.1 NSS File Systems on EVMS-Managed Devices

Use only an NSS tool (such as NSSMU or the Storage plug-in to iManager) to create a pool on a new EVMS-managed device. The tool automatically carves out a partition with the DOS Segment Manager so that the device can be used later for either NSS or Linux POSIX file systems. Then the tool adds the NetWare Segment Manager and creates the NSS partition and pool.

For the best performance, if you plan to use a non-system device for both NSS and Linux POSIX file systems, create the NSS file systems on the device first. NSS partitions the device in a manner that ensures the best performance for the NSS file systems, and does not adversely affect performance for Linux POSIX file systems.

For instructions for creating pools and volumes, see the Managing NSS Pools and Managing NSS Volumes in the OES 2 SP3: NSS File System Administration Guide for Linux.

A.4.2 Linux POSIX File Systems on EVMS-Managed Devices

Use the Linux EVMSGUI tool (evmsgui) to create Linux POSIX file systems on the EVMS-managed device. For EVMS-managed devices, Linux POSIX file systems require that the Linux partitions be managed by the DOS Segment Manager (DOSSegMgr). This is laid down automatically if you first create an NSS file system on the device.

WARNING:EVMS administration utilities (evms, evmsgui, and evmsn) should not be running when they are not being used. EVMS utilities lock the EVMS engine, which prevents other EVMS-related actions from being performed. This affects both NSS and Linux POSIX volume actions.

NSS and Linux POSIX volume cluster resources should not be migrated while any of the EVMS administration utilities are running.

Failure to observe this warning could cause a system hang and lead to data corruption.

Consider the following guidelines when working with EVMSGUI to create a Linux POSIX partition:

Scenario	To create the Linux partition in evmsgui:
Free space is controlled by the DOS Segment Manager.	Create the Linux partition as usual.
Disk is not initialized.	Select No at the prompt to initialize. On a pure SLES system (no NSS), ignore this step. Delete the disk object from the Volumes tab. Add the DOS Segment Manager to the device. Create the Linux partition as usual.
Free space is controlled by the NetWare Segment Manager.	Do one of the following: If no partitions are on the device, remove the NetWare Segment Manager from the device, add the DOS Segment Manager, then create the partition as usual. WARNING:Changing the segment manager initializes the disk again (destroys existing data), so you should do this only with a disk that has no partitions on it, or if you do not want any of the partitions that are currently on the disk. If partitions exist, reboot the server to automatically give control of the device back to the DOS Segment Manager, then create the partition as usual.

If no partitions are on the device, use the following procedure to add a DOS Segment Manager to a non-clustered device:

Log in as the root user, open a terminal console, then enter
```
evmsgui
```
If necessary, remove the NetWare Segment Manager:
1. Click the Disks tab, then locate and select the device, such as device sdb.
2. Right-click the device, then select Remove segment manager from Object.
  
  This option appears only if there is an existing segment manager for the selected disk.
3. Select the listed segment manager, click Remove, then click OK.
  
  WARNING:All data on the selected disk space is destroyed.
4. Click Save, then click Save again to save your changes.
Add the DOS Segment Manager:
1. From the EVMSGUI menu, click Actions > Add > Segment Manager to Storage Object.
2. On the Add Segment Manager to Storage Object page, select DOS Segment Manager, then click Next.
3. On the Select Plugin Acceptable Objects page, select the device where you want to add the segment manager, then click Next.
4. On the Configurable Options page, select the disk type (Linux is the default), click Add, then click OK.
5. Click Save, then click Save again to save your changes.
Create a segment for the DOS Segment Manager.

The DOS Segment Manager requires you to create a segment before creating an EVMS volume. Without a segment, the additional segment manager does not appear when you attempt to create an EVMS volume.
1. From the evmsgui menu, click Actions > Create > Segment.
2. On the Create Disk Segment page, select DOS Segment Manager, then click Next.
3. On the Select Plugin Acceptable Objects page, select the device where you want to add the segment, then click Next.
4. Specify the size of the segment, the partition type (such as Linux LVM), click Create, then click OK.
5. Click Save, then click Save again to save your changes.

For information about adding or changing segment managers when you are clustering a shared device with Novell Cluster Services, see Creating Linux POSIX Volumes on Shared Devices in the OES 2 SP3: Novell Cluster Services 1.8.8 Administration Guide for Linux.