Solaris 10 8/07 Installation Guide: Planning for Installation and Upgrade

Chapter 9 Creating RAID-1 Volumes (Mirrors) During Installation (Planning)

This chapter describes the requirements and guidelines that are necessary to create RAID-1 volumes with the custom JumpStart or Solaris Live Upgrade installation methods.

This chapter describes the following topics.

For additional information specific to Solaris Live Upgrade or JumpStart, see the following references:

System Requirement

To create RAID-1 volumes to duplicate data on specific slices, the disks that you plan to use must be directly attached and available to the system during the installation.

State Database Replicas Guidelines and Requirements

You should distribute state database replicas across slices, drives, and controllers, to avoid single points of failure. You want a majority of replicas to survive a single component failure. If you lose a replica, when a device fails, for example, the failure might cause problems with running Solaris Volume Manager software or when rebooting the system. Solaris Volume Manager software requires at least half of the replicas to be available to run, but a majority (half plus one) to reboot into multiuser mode.

For detailed instructions about creating and administering state database replicas, see Solaris Volume Manager Administration Guide.

Selecting Slices for State Database Replicas

Before selecting slices for state database replicas, consider the following guidelines and recommendations.

Task 

Description 

Choose a dedicated slice 

You should create state database replicas on a dedicated slice of at least 4 MB per replica. If necessary, you could create state database replicas on a slice that is to be used as part of a RAID-0 or RAID-1 volume. You must create the replicas before you add the slice to the volume. 

Resize a slice 

By default, the size of a state database replica is 4 MB or 8192 disk blocks. Because your disk slices might not be that small, you can resize a slice to hold the state database replica. For information about resizing a slice, see Chapter 11, Administering Disks (Tasks), in System Administration Guide: Devices and File Systems.

Choose a slice that is not in use 

You can create state database replicas on slices that are not in use. The part of a slice that is reserved for the state database replica should not be used for any other purpose.

 

You cannot create state database replicas on existing file systems, or the root (/), /usr, and swap file systems. If necessary, you can create a new slice (provided a slice name is available) by allocating space from swap and then put state database replicas on that new slice.

Choosing a slice that becomes a volume 

When a state database replica is placed on a slice that becomes part of a volume, the capacity of the volume is reduced by the space that is occupied by the replica or replicas. The space that is used by a replica is rounded up to the next cylinder boundary and this space is skipped by the volume.  

Choosing the Number of State Database Replicas

Before choosing the number of state database replicas, consider the following guidelines.

Distributing State Database Replicas Across Controllers

If multiple controllers exist, replicas should be distributed as evenly as possible across all controllers. This strategy provides redundancy if a controller fails and also helps balance the load. If multiple disks exist on a controller, at least two of the disks on each controller should store a replica.

RAID-1 and RAID-0 Volume Requirements and Guidelines

When you are working with RAID-1 volumes (mirrors) and RAID-0 volumes (single-slice concatenations), consider the following guidelines.

Custom JumpStart and Solaris Live Upgrade Guidelines

The custom JumpStart installation method and Solaris Live Upgrade support a subset of the features that are available in the Solaris Volume Manager software. When you create mirrored file systems with these installation programs, consider the following guidelines.

Installation Program 

Supported Feature  

Unsupported Feature 

Custom JumpStart and Solaris Live Upgrade 

  • Supports RAID-0 and RAID-1 volumes, but does not support other Solaris Volume Manager components, such as RAID-5 volumes.

  • RAID-0 volume is supported, but only as a single-slice concatenation.

In Solaris Volume manager a RAID-0 volume can refer to disk stripes or disk concatenations. You cannot create RAID-0 stripe volumes during the installation or upgrade. 

Custom JumpStart 

  • Supports the creation of RAID-1 volumes during an initial installation only.

  • You can create up to two RAID-0 volumes (submirrors) for each RAID-1 volume. Two submirrors usually provide sufficient data redundancy for most applications, and the disk drive costs are less expensive.

  • Does not support an upgrade when RAID-1 volumes are configured.

  • More than two RAID-0 volumes are not supported.

Solaris Live Upgrade 

  • You can create up to three RAID-0 volumes (submirrors) for each RAID-1 volume. Three submirrors enable you to take a submirror offline and perform a backup while maintaining the two remaining submirrors for continued data redundancy.

  • Supports the creation of RAID-1 volumes during an upgrade.

For examples, see To Create a Boot Environment With RAID-1 Volumes (Mirrors) in Solaris 10 8/07 Installation Guide: Solaris Live Upgrade and Upgrade Planning.

More than three RAID-0 volumes are not supported. 

Creating and Installing a Solaris Flash with RAID-1 volumes 

You can create a Solaris Flash archive created from a master system that has Solaris Volume Manager RAID-1 volumes configured. The Solaris Flash creation software removes all RAID-1 volume information from the archive to keep the integrity of the clone system. With custom JumpStart you can rebuild the RAID-1 volumes by using a JumpStart profile. With Solaris Live Upgrade, you create a boot environment with RAID-1 volumes configured and install the archive. The Solaris installation program cannot be used to install RAID-1 volumes with a Solaris Flash archive. 

For examples of RAID-1 volumes in JumpStart profiles, see Profile Examples in Solaris 10 8/07 Installation Guide: Custom JumpStart and Advanced Installations.

Veritas VxVM stores configuration information in areas not available to Solaris Flash. If Veritas VxVm file systems have been configured, you should not create a Solaris Flash archive. Also, Solaris install, including JumpStart and Solaris Live Upgrade do not support rebuilding VxVM volumes at installation time. Therefore, if you are planning to deploy Veritas VxVM software using a Solaris Flash archive, the archive must be created prior to configuring the VxVM file systems. The clone systems must be then configured individually after the archive has been applied and the system rebooted. 

RAID Volume Name Requirements and Guidelines for Custom JumpStart and Solaris Live Upgrade

Observe the following rules when assigning names for volumes.

RAID Volume Naming Conventions for Solaris Live Upgrade

When you use the Solaris Live Upgrade to create RAID-1 volumes (mirrors) and RAID-0 volumes (submirrors), you can enable the software to detect and assign volume names, or you can assign the names. If you enable the software to detect the names, the software assigns the first mirror or submirror name that is available. If you assign mirror names, assign names ending in zero so that the installation can use the names ending in 1 and 2 for submirrors. If you assign submirror names, assign names ending in 1 or 2. If you assign numbers incorrectly, the mirror might not be created. For example, if you specify a mirror name with a number that ends in 1 or 2 (d1 or d2), Solaris Live Upgrade fails to create the mirror if the mirror name duplicates a submirror's name.


Note –

In previous releases, an abbreviated volume name could be entered. Starting with the 10 8/07 release, only the full volume name can be entered. For example, only the full volume name, such as /dev/md/dsk/d10, can be used to specify a mirror.



Example 9–1 Solaris Live Upgrade: Enable the Software to Detect and Name the Mirror and Submirror

In this example, Solaris Live Upgrade assigns the volume names. The RAID-1 volumes d0 and d1 are the only volumes in use. For the mirror d10, Solaris Live Upgrade chooses d2 for the submirror for the device c0t0d0s0 and d3 for the submirror for the device c1t0d0s0.


lucreate -n newbe -m /:/dev/md/dsk/d10:mirror,ufs -m /:/dev/dsk/c0t0d0s0:attach
-m /:/dev/dsk/c1t0d0s0:attach


Example 9–2 Solaris Live Upgrade: Assign Mirror and Submirror Names

In this example, the volume names are assigned in the command. For the mirror d10, d11 is the name for the submirror for the device c0t0d0s0 and d12 is the name for the submirror for the device c1t0d0s0.


lucreate -n newbe -m /:/dev/md/dsk/d10:mirror,ufs -m /:/dev/dsk/c0t0d0s0,/dev/md/dsk/d11:attach
-m /:/dev/dsk/c1t0d0s0,/dev/md/dsk/d12:attach

For detailed information about Solaris Volume Manager naming requirements, see Solaris Volume Manager Administration Guide.


RAID-Volume Naming Conventions for Custom JumpStart

When you use the custom JumpStart installation method to create RAID-1 volumes (mirrors) and RAID-0 volumes (submirrors), you can enable the software to detect and assign volume names to mirrors, or you can assign the names in the profile.


Note –

You can abbreviate the names of physical disk slices and Solaris Volume Manager volumes. The abbreviation is the shortest name that uniquely identifies a device. Examples follow.



Example 9–3 Enable the Software to Detect the Mirror and Submirror Names

In the following profile example, the mirror is assigned the first volume numbers that are available. If the next available mirror ending in zero is d10, then the names d11 and d12 are assigned to the submirrors.

filesys                 mirror c0t0d0s1  / 


Example 9–4 Assigning Mirror and Submirror Names

In the following profile example, the mirror number is assigned in the profile as d30. The submirror names are assigned by the software, based on the mirror number and the first available submirrors. The submirrors are named d31 and d32.

filesys                 mirror:d30 c0t1d0s0 c0t0d0s0  /

For detailed information about Solaris Volume Manager naming requirements, see Solaris Volume Manager Administration Guide.

Guidelines for Selecting Disks and Controllers

When you choose the disks and controllers that you want to use to mirror a file system, consider the following guidelines.

Guidelines for Selecting Slices

When you choose the slices that you want to use to mirror a file system, consider the following guidelines.

Booting Into Single-User Mode Causes Mirror to Appear to Need Maintenance

If a system with mirrors for root (/), /usr, and swap is booted into single-user mode, the system indicates that these mirrors are in need of maintenance. When you view these mirrors with the metastat command, these mirrors, and possibly all mirrors on the system, appear in the “Needing Maintenance” state.

Though this situation appears to be potentially dangerous, do not be concerned. The metasync -r command, which normally occurs during boot to resynchronize mirrors, is interrupted when the system is booted into single-user mode. After the system is rebooted, the metasync -r command runs and resynchronizes all mirrors.

If this interruption is a concern, run the metasync -r command manually.

For more information about the metasync, see the metasync(1M) man page, and Solaris Volume Manager Administration Guide.