9 Configuring Software RAID1 for the Root Partition

9.1 Prerequisites for Using a Software RAID1 Device for the Root Partition
9.2 Enabling iSCSI Initiator Support at Install Time
9.3 Enabling Multipath I/O Support at Install Time
9.4 Creating a Software RAID1 Device for the Root (/) Partition

In SUSE Linux Enterprise Server, the Device Mapper RAID tool has been integrated into the YaST Partitioner. You can use the partitioner at install time to create a software RAID1 for the system device that contains your root (/) partition. The /boot partition must be created on a separate device than the MD RAID1.

9.1 Prerequisites for Using a Software RAID1 Device for the Root Partition #

Ensure that your configuration meets the following requirements:

You need two hard drives to create the RAID1 mirror device. The hard drives should be similarly sized. The RAID assumes the size of the smaller drive. The block storage devices can be any combination of local (in or directly attached to the machine), Fibre Channel storage subsystems, or iSCSI storage subsystems.
You need a third device to use for the /bootpartition. The boot device should be a local device.
If you are using hardware RAID devices, do not attempt to run software RAIDs on top of it.
If you are using iSCSI target devices, you must enable the iSCSI initiator support before you create the RAID device.
If your storage subsystem provides multiple I/O paths between the server and its directly attached local devices, Fibre Channel devices, or iSCSI devices that you want to use in the software RAID, you must enable the multipath support before you create the RAID device.

9.2 Enabling iSCSI Initiator Support at Install Time #

If there are iSCSI target devices that you want to use for the root (/) partition, you must enable the iSCSI Initiator software to make those devices available to you before you create the software RAID1 device.

Proceed with the YaST install of SUSE Linux Enterprise Server until you reach the Installation Settings page.
Click Partitioning to open the Preparing Hard Disk page, click Custom Partitioning (for experts), then click Next.
On the Expert Partitioner page, expand Hard Disks in the System View panel to view the default proposal.
On the Hard Disks page, select ConfigureConfigure iSCSI, then click Continue when prompted to continue with initializing the iSCSI initiator configuration.

9.3 Enabling Multipath I/O Support at Install Time #

If there are multiple I/O paths to the devices that you want to use for the root (/) partition, you must enable multipath support before you create the software RAID1 device.

Proceed with the YaST install of SUSE Linux Enterprise Server until you reach the Installation Settings page.
Click Partitioning to open the Preparing Hard Disk page, click Custom Partitioning (for experts), then click Next.
On the Expert Partitioner page, expand Hard Disks in the System View panel to view the default proposal.
On the Hard Disks page, select ConfigureConfigure Multipath, then click Yes when prompted to activate multipath.
This re-scans the devices and resolves the multiple paths so that each device is listed only once in the list of hard disks.

9.4 Creating a Software RAID1 Device for the Root (/) Partition #

Proceed with the YaST install of SUSE Linux Enterprise Server until you reach the Installation Settings page.
Click Partitioning to open the Preparing Hard Disk page, click Custom Partitioning (for experts), then click Next.
On the Expert Partitioner page, expand Hard Disks in the System View panel to view the default proposal, select the proposed partitions, then click Delete.
Create a /boot partition.
1. On the Expert Partitioner page under Hard Disks, select the device you want to use for the /boot partition, then click Add on the Hard Disk Partitions tab.
2. Under New Partition Type, select Primary Partition, then click Next.
3. Under New Partition Size, specify the size to use, then click Next.
4. Under Format Options, select Format partition, then select your preferred file system type (such as Ext2 or Ext3) from the drop-down list.
5. Under Mount Options, select Mount partition, then select /boot from the drop-down list.
6. Click Finish.
Create a swap partition.
1. On the Expert Partitioner page under Hard Disks, select the device you want to use for the swap partition, then click Add on the Hard Disk Partitions tab.
2. Under New Partition Type, select Primary Partition, then click Next.
3. Under New Partition Size, specify the size to use, then click Next.
4. Under Format Options, select Format partition, then select Swap from the drop-down list.
5. Under Mount Options, select Mount partition, then select swap from the drop-down list.
6. Click Finish.
Set up the 0xFD Linux RAID format for each of the devices you want to use for the software RAID1.
1. On the Expert Partitioner page under Hard Disks, select the device you want to use in the RAID1, then click Add on the Hard Disk Partitions tab.
2. Under New Partition Type, select Primary Partition, then click Next.
3. Under New Partition Size, specify to use the maximum size, then click Next.
4. Under Format Options, select Do not format partition, then select 0xFD Linux RAID from the drop-down list.
5. Under Mount Options, select Do not mount partition.
6. Click Finish.
7. Repeat Step 6.a to Step 6.f for each device that you plan to use in the software RAID1.
Create the RAID device.
1. In the System View panel, select RAID, then click Add RAID on the RAID page.
  The devices that you prepared in Step 6 are listed in Available Devices.
2. Under RAID Type, select RAID 1 (Mirroring).
3. In the Available Devices panel, select the devices you want to use for the RAID, then click Add to move the devices to the Selected Devices panel.
  Specify two or more devices for a RAID1.
  To continue the example, two devices are selected for RAID1.
4. Click Next.
5. Under RAID Options, select the chunk size from the drop-down list.
  The default chunk size for a RAID1 (Mirroring) is 4 KB.
  Available chunk sizes are 4 KB, 8 KB, 16 KB, 32 KB, 64 KB, 128 KB, 256 KB, 512 KB, 1 MB, 2 MB, or 4 MB.
6. Under Formatting Options, select Format partition, then select the file system type (such as Ext3) from the File system drop-down list.
7. Under Mounting Options, select Mount partition, then select / from the Mount Point drop-down list.
8. Click Finish.
  The software RAID device is managed by Device Mapper, and creates a device under the /dev/md0 path.
On the Expert Partitioner page, click Accept.
The new proposal appears under Partitioning on the Installation Settings page.
For example, the setup for the
Continue with the install.
Whenever you reboot your server, Device Mapper is started at boot time so that the software RAID is automatically recognized, and the operating system on the root (/) partition can be started.

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