Using EVMS to Manage Devices

This section describes how to configure EVMS as the volume manager of your devices.

Configuring the System Device at Install to Use EVMS

This section describes how to configure the system device during the Linux install to use EVMS as the volume manager instead of the current default of Linux Volume Manager (LVM).

Before the Install

System Device

For the purposes of this install documentation, a system device is any device that contains the Linux /boot, swap, or root (/) partitions for your Linux computer.

The install instructions assume the following:

  • All three system partitions are on the same physical disk.

    If you use different disks for any of the system partitions, make sure to modify the install instructions for your deployment scenario so that all of the system partitions are managed by EVMS.

  • You must configure the boot partition within the BIOS-addressable space (such as 2 GB for x86 or 8 GB for x86-64) of the first disk recognized by the system.

    If this restriction is not required for your hardware, you can modify the location of the /boot partition as desired.

  • Your system uses the Grub or LILO boot loaders.

    If you have an IA64 system, you must modify these install instructions to use the ELILO boot loader (/boot/efi/elilo.conf) instead.

    [Warning]Warning

    Whenever you manually alter the kernel or initrd on your system, make sure to run /sbin/elilo before shutting down the computer. If you leave out this step, your system might not be bootable.

Device Size Limits

Version 2.3 and later of mdadm supports component devices up to 4 TB in size each. Earlier versions support component devices up to 2 TB in size.

[Important]Important

If you have a local disk, external disk arrays, or SAN devices that are larger than the supported device size, use a third-party disk partitioner to carve the devices into smaller logical devices.

You can combine up to 28 component devices to create the RAID array. The md RAID device you create can be up to the maximum device size supported by the file system you plan to use. For information about file system limits for SUSE® Linux Enterprise Server 10, see “Large File System Support” in the SUSE Linux Enterprise Server 10 Installation and Administration Guide..

Data Loss Considerations for the System Device

This install requires that you delete the default partitioning settings created by the install, and create new partitions to use EVMS instead. This destroys all data on the disk.

[Warning]Warning

To avoid data loss, it is best to use the EVMS install option only on a new device.

If you have data volumes on the system device, take one or more of the following precautionary measures:

  • Move the data volumes from the system device to another device.

  • If you cannot move the volumes, make a backup copy of the data, so you can restore the data volumes later from a backup copy.

Storage Deployment Considerations for the System Device

By default, the YaST install for SUSE Linux Enterprise Server uses the Linux Volume Manager to manage the system device. The install procedures in this section describe how to install SUSE Linux Enterprise Server with EVMS as the volume manager of the system device. The instructions assume the following:

  • You want to use EVMS to manage the system device.

  • Only the system device is to be configured during the install.

  • Other devices on the system are not configured during the install, or are attached to the server later. These additional devices are configured only after the system is operating and performing as expected.

During the Server Install

To install Linux with EVMS as the volume manager for your boot and system partitions, you must modify the Partitioning configuration in the Installation Settings.

[Warning]Warning

The following procedure destroys all data on the system device.

  1. Begin the install, according to the instructions provided in Deployment in the SUSE Linux Enterprise 10 Installation and Administration Guide.

  2. When the installation reaches the Installations Settings screen, delete the proposed LVM-based partioning solution. This deletes the proposed partitions and the partition table on the system device so that the device can be marked to use EVMS as the volume manager instead of LVM.

    1. In the list of Installation Settings, select Partitioning.

    2. In the Partitioning menu, select Create Custom Partition Setup, then click Next.

    3. Select Custom Partition - for Experts, then click Next to open the Expert Partitioner dialog box.

    4. Select Expert > Delete Partition Table and Disk Label, then click Yes twice to continue through the Warning advisories.

      This deletes the recommended partitions and the partition table on the system disk.

  3. Create a primary partition on the system disk to use as the boot partition:

    1. Click Create.

    2. From the list of devices, select the device you want to use for the boot partition, such as /dev/hda, then click OK.

      If you have a single system disk, only one device is available, and you are not prompted to choose the device.

    3. Select Primary Partition, then click OK.

    4. Select Format, then select the native Linux file system you want to use, such as Ext3.

      [Important]Important

      In a paravirtualized environment, use Ext2 as the file system for the boot device.

    5. In Size (End Value) field, specify 200 MB or larger.

      For example, to set the size at 300 MB, type 300M.

    6. Set the mount point to /boot.

    7. Click OK.

      The partition appears as a logical device in the devices list, such as /dev/hda1.

  4. Create a second primary partition on the system disk to use for both the swap and system volumes:

    1. Click Create.

    2. From the list of devices, select the device you want to use for the second primary partition, such as /dev/hda, then click OK.

      If you have a single system disk, only one device is available and you are not prompted to choose the device.

    3. Select Primary Partition, then click OK.

    4. Select Do Not Format, then select Linux LVM (0x8E) from the list of file system IDs.

    5. In Size (End Value field), set the cylinder End value to 5 GB or larger, depending on the combined partition size you need to contain your system and swap volumes.

      [Important]Important

      Do not make the system partition larger than necessary. The remaining space on the system disk can be used to create NSS volumes or native Linux volumes that are managed by EVMS.

      To determing how much space to use, consider the following recommendations:

      • For your system volume, allow 2 GB (minimum) to 10 GB (recommended), depending on the OES services that you intend to install.

      • If you intend to create additional NSS volumes on the same physical disk, you must leave unpartitioned space available.

      • Set aside 128 MB or larger for the swap volume.

        Swap management is different for Linux kernel 2.4.10 and later. How much swap to add depends on the RAM size, the tasks that are planned for the system, and whether you want to make more virtual memory available than the RAM provides.

        Some swap (at least 128 MB) is good to have to minimize the risk of losing data when active processes run out of RAM space. Swap is not required for systems with more than 1 GB of RAM. You must have at least 1 GB of virtual memory (RAM plus swap) during the install, but if the swap is more than 2 GB, you might not be able to install on some machines.

      • The total size should be the size you need for your system volume plus the size you need for your swap volume.

      For example, if you have a 20 GB hard drive with 2 GB of RAM and plan to install all of the OES services on the system volume, your system partition should be at least 11 GB. The remaining 9 GB should remain as free unpartitioned space that can be used for NSS volumes or other Linux partitions that you might want to create later.

    6. Click OK.

      The partition appears as a logical device in the devices list, such as /dev/hda2.

  5. Modify the volume management type from LVM to EVMS for the second primary partition you created in Step 4:

    1. At the bottom of the page, click EVMS.

      Available partitions for EVMS appear as devices under /dev/evms, such as /dev/evms/hda2.

    2. In the EVMS Configurator, select the LVM partition created in Step 4, then click Create Container.

    3. In the Create EVMS Container dialog box, select the partition, specify the container name (such as system), then click Add Volume to create the lvm/system container, where system is the container name.

    4. Click OK.

      The EVMS Configurator displays the lvm/system container you just created, its size, and free space.

  6. Create the swap volume in the lvm/system container:

    1. Select lvm/system, then click Add.

    2. In the Create Logical Volume dialog box, select Format, then select Swap from the File System drop-down menu.

    3. Specify swap as the volume name.

    4. Specify 1 GB (recommended) for the swap volume.

      The swap size should be 128 MB or larger, with a recommended size of 1 GB. For an explanation of this recommendation, see Step 4.e.

    5. Specify the mount point as swap.

    6. Click OK.

  7. Create the system volume in the lvm/system container:

    1. Select lvm/system, then click Add.

    2. In the Create Logical Volume dialog box, select Format, then select the file system to use from the File System drop-down menu, such as Reiser or Ext3.

    3. In the Volume Name field, specify a volume name, such as sys_lx.

    4. In the Size field, click Max to set the size of the system volume as the remaining space available in the lvm/system partition.

    5. Specify the mount point as / (root volume).

    6. Click OK.

  8. Click Next to return to the list of devices.

    Below is an example of the physical and logical devices that should be configured on your system. Your setup depends on the number of devices in the server and the sizes you choose for your partitions.

    Device

    Size

    F

    Type

    Mount

    Start

    End

    Used By

    /dev/hda

    149.0 GB

    6Y160p0

    0

    19456

    /dev/hda1

    305.9 MB

    F

    Linux Native (Reiser)

    /boot

    0

    38

    /dev/hda2

    20.0 GB

    Linux LVM

    39

    2649

    EVMS lvm/system

    /dev/hdb

    111.8 GB

    SP1203N

    0

    14595

    /dev/evms/lvm/system/sys_lx

    10.0 GB

    F

    EVMS

    /

    -

    -

    /dev/evms/lvm/system/swap

    1.0 GB

    F

    EVMS

    swap

    -

    -

  9. Click Next to return to the Installation Settings page.

    You can dismiss the message warning that you should not mix EVMS and non-EVMS partitions on the same device.

  10. Continue with the SUSE Linux Enterprise Server installation.

    [Important]Important

    After the install is complete, make sure to perform the mandatory post-install configuration of the related system settings to ensure that the system device functions properly under EVMS. Otherwise, the system fails to boot properly.

    For information, see Section 2.1.3, “After the Server Install”.

After the Server Install

After the SUSE Linux Enterprise Server 10 install is complete, you must perform the following tasks to ensure that the system device functions properly under EVMS:

Edit the /etc/fstab File

When you boot the system, the kernel reads the /etc/fstab file to identify which file systems should be mounted and then mounts them. This file contains a table of file system information about the root (/), /boot, and swap partitions plus other partitions and file systems you want to mount.

The /boot partition is separate from the EVMS container where you placed the root (/) and swap partitions and is not managed by EVMS at this time. However, in the following steps, you disable boot.lvm and boot.md, then enable boot.evms. In effect, this forces EVMS to scan all the partitions at boot time, including the /boot partition, and it activates /boot under the /dev/evms directory. Therefore, this makes /boot a partition that is discovered by EVMS at startup, and requires that the device be listed under /dev/evms in the fstab file so it can be found when booting with boot.evms. You must edit the /etc/fstab file to modify the location of the /boot partition so it is under the /dev/evms directory.

In fstab, the entry for the boot device might present the boot device by the device node name (such as /dev/sda1) or by the UUID pathname (such as /dev/disk/by-id/scsi-SServeRA_Drive_1_600BC00000-part1). In ether case, that name for the boot device must be changed to include evms in the path, such as /dev/evms/sda1.

The procedure in this section shows how to change /dev/sda1 to /dev/evms/sda1. Replace sda1 with the device name of the device you used for your /boot partition.

[Important]Important

When working in the /etc/fstab file, do not leave any stray characters or spaces in the file. This is a configuration file, and it is highly sensitive to such mistakes.

To modify the path of the boot device in the /etc/fstab file, complete the following procedure:

  1. Open the /etc/fstab file in a text editor.

  2. Locate the line that contains the /boot partition.

    For example, if your /boot partition uses device sda1 and the Reiser file system, look for a line similar to this:

    /dev/sda1 /boot reiser defaults 1 1
    
  3. In the Device Name column, modify the location of the /boot partition from /dev to /dev/evms so it can be managed by EVMS. Modify only the device name by adding /evms to the path:

    /dev/evms/sda1 /boot reiser defaults 1 1

  4. Save the file.

    The changes do not take effect until the server is restarted. Do not restart at this time.

  5. Continue with Section 2.1.3.2, “Make a New initrd”.

Make a New initrd

  1. Open a terminal console, and log in as the root user.

  2. At the console prompt, enter

    mkinitrd
    

    This creates a new initrd file with the correct settings for the boot device. The changes do not take effect until the server is restarted. Do not restart at this time.

  3. Continue with Section 2.1.3.3, “Disable the boot.lvm and boot.md Services”.

Disable the boot.lvm and boot.md Services

Disable the boot.lvm and boot.md services so they do not run at boot time (runlevel B). EVMS now handles the boot.

  1. In YaST, click System > System Services (Runlevel) > Expert Mode.

  2. Select boot.lvm.

  3. Click Set/Reset > Disable the Service.

  4. Select boot.md.

  5. Click Set/Reset > Disable the Service.

  6. Click Finish, then click Yes.

    The changes do not take effect until the server is restarted. Do not restart at this time.

  7. Continue with Section 2.1.3.4, “Enable the boot.evms Service”.

Enable the boot.evms Service

The boot.evms service should be enabled automatically after the install, but you should verify that it is enabled.

  1. In YaST, click System > System Services (Runlevel) > Expert Mode.

  2. Select boot.evms.

  3. Click Set/Reset > Enable the Service.

    The B runlevel option is automatically selected.

  4. Click Finish, then click Yes.

    The changes do not take effect until the server is restarted.

    [Note]Note

    Effective in SUSE Linux Enterprise 10, the /dev directory is on tmpfs, and the device nodes are automatically re-created on boot. It is no longer necessary to modify the /etc/init.d/boot.evms script to delete the device nodes on system restart, as was required for previous versions of SUSE Linux.

  5. Continue with Section 2.1.3.5, “Restart the Server”.

Restart the Server

  1. Restart the server to apply the post-install configuration settings.

  2. On restart, if the system device does not appear, it might be because EVMS has not been activated. At the prompt, enter

    evms_activate
    

Verify the System Services

After the post-install configuration is complete and you have restarted the server, make sure the server is operating as expected.


SUSE® Linux Enterprise Server Storage Administration Guide 10