C H A P T E R 3

Volume Management

The master configuration file (`mcf`) describes all devices that are under the control of, or used by, the Sun StorEdge QFS or Sun StorEdge SAM-FS software. When you create this file, you declare attributes for each device, and you group the devices comprising each file system into family sets.

The installation and configuration process is described completely in the Sun StorEdge QFS and Sun StorEdge SAM-FS Software Installation and Configuration Guide. This chapter provides additional information about configuring the file systems used in the Sun StorEdge QFS and Sun StorEdge SAM-FS environments. This chapter contains the following sections:

- Creating the mcf File

- Examples of mcf Files

- Interactions Between File Settings, Options, and Directives

- Initializing a File System

- Configuration Examples

Note - References to Sun StorEdge SAM-FS also apply to Sun SAM-QFS configurations when talking about storage and archive management. References to Sun StorEdge QFS also apply to Sun SAM-QFS configurations when talking about file system design and capabilities. This section refers to Sun SAM-QFS only when needed for clarity.

##

Creating the`mcf` File

The first step toward configuring a Sun StorEdge QFS or Sun StorEdge SAM-FS file system is to create a master configuration file in`/etc/opt/SUNWsamfs/mcf`. The`mcf` file contains the information that these file systems need in order to identify and organize RAID and disk devices into file systems. It also contains entries for each automated library or device included in a file system. A sample`mcf` file is located in`/opt/SUNWsamfs/examples/mcf`.

An`mcf` file is an ASCII file that consists of lines of specification code divided into six columns, or fields. CODE EXAMPLE 3-1 shows the six fields in an `mcf` file line.

CODE EXAMPLE 3-1 Fields in an `mcf` File
         Equipment    Equipment    Equipment    Family    Device    Additional
         Identifier   Ordinal      Type         Set       State     Parameters

The following rules pertain to how data can be entered in the`mcf` file:

- Enter either space or tab characters between the fields in the file.

- You can include comment lines in an `mcf` file. Comment lines start with a pound character (`#`).

- Some fields do not need to contain useful information. Use a dash character (-) to indicate that an optional field contains no meaningful information.

For more information about writing the`mcf` file, see the`mcf`(4) man page. You can also use the SAM-QFS Manager to create an `mcf` file. For information about installing SAM-QFS Manager, see Sun StorEdge QFS and Sun StorEdge SAM-FS Software Installation and Configuration Guide. For information about using SAM-QFS Manager, see its online help.

The following sections describe each field in an `mcf` file:

- The Equipment Identifier Field

- The Equipment Ordinal Field

- The Equipment Type Field

- The Family Set Field

- The Device State Field

- The Additional Parameters Field

### The Equipment Identifier Field

The Equipment Identifier field is a required field. Use the Equipment Identifier field to specify the following kinds of information:

- The file system name. If this field contains a file system name, it must be identical to the Family Set name, and the subsequent lines in the `mcf` file must define all the disks or devices included in the file system. More than one file system can be declared in an`mcf` file. Typically, the first data line in an`mcf` file declares the first file system, and subsequent lines specify the devices included in the file system. Other file systems declared in the`mcf` file can be preceded by a blank comment line for readability. File system names must start with an alphabetic character and can contain only alphabetic characters, numeric characters, or underscore (_) characters.

- The `nodev` keyword. If this field contains the keyword`nodev`, the`mcf` file is being used as a client host in a Sun StorEdge QFS shared file system on a Solaris host. Do not use this keyword if you are running in a Sun Cluster environment. This keyword can appear in this field only as the Equipment Identifier for one or more metadata devices that reside on the metadata server. For more information about creating an`mcf` file for the members of a Sun StorEdge QFS shared file system, see the Sun StorEdge QFS and Sun StorEdge SAM-FS Software Installation and Configuration Guide.

- A disk partition or slice description. A`/dev/` entry in this field identifies a disk partition or slice.

- An automated library or optical drive description. If this field is a`/dev/samst` entry, it identifies an automated library or optical drive. If you are configuring a network-attached automated library, see the Sun StorEdge QFS and Sun StorEdge SAM-FS Software Installation and Configuration Guide and the Sun StorEdge SAM-FS Storage and Archive Management Guide for more information.

- A tape drive description. If the field is a tape drive, the entry can be in one of two forms:

- The field can contain a `/dev/rmt` entry.

- The field can contain a path to a symbolic link that points to the same special file that the `/dev/rmt` link points to. If you specify a tape drive in this manner, make sure you create the link before mounting the file system.

If the Equipment Identifier field contains the name of a Family Set, it is limited to 31 characters. For all other content, this field is limited to 127 characters.

### The Equipment Ordinal Field

For each row in the `mcf` file, the Equipment Ordinal field must contain a numeric identifier for the file system component or device being defined. Specify a unique integer such that 1 eq_ord 65534. This is a required field.

### The Equipment Type Field

Enter a 2-, 3-, or 4-character code for the Equipment Type field. This is a required field.

As TABLE 3-1 shows, a Sun StorEdge SAM-FS file system can contain either `ms` or `md` in the Equipment Type field.

TABLE 3-1 Sun StorEdge SAM-FS Equipment Type Field
Equipment Type Field Content | Meaning
--- | ---
`ms` | ``Defines a Sun StorEdge SAM-FS file system.
`md` | ``Defines a striped or round-robin device for storing file data and metadata information.

As TABLE 3-2 shows, a Sun StorEdge QFS or Sun SAM-QFS file system can contain either `ma`, `md`, `mm`, `mr`, or `g` XXX in the Equipment Type field.

TABLE 3-2 Sun StorEdge QFS or Sun SAM-QFS Equipment Type Field
Equipment Type Field Content | Meaning
--- | ---
`ma` | ``Defines a Sun StorEdge QFS or Sun SAM-QFS file system.
`md` | Defines a striped or round-robin device for storing file data.
`mm` | ``Defines a metadata device for storing inode and other nondata information.
`mr` | ``Defines a ``round-robin or ``striped data device.
`g` XXX | Striped ``group ``data device. Striped groups start with the letter`g` followed by a number. The number must be an integer such that `0` `` XXX`` `127`. For example, `g12`. All members in a striped group must be the same type and size. Different striped groups within one file system are not required to have the same number of members. `md`, `mr`, and `g` XXX devices cannot be mixed in one file system.

Besides the file system equipment types, other codes are used to identify automated libraries and other devices. For more information about specific equipment types, see the`mcf`(4) man page.

### The Family Set Field

The Family Set field contains the name for a group of devices. This is a required field.

Family Set names must start with an alphabetic character and can contain only alphabetic characters, numeric characters, or underscore (_) characters.

For lines that define a file system, the lines that define the disk devices in a file system must all contain the same Family Set name. The software uses the Family Set to groups devices with the same Family Set name together as a file system. It physically records the Family Set name on all the devices in the file system when the `sammkfs`(1M) command is issued. You can change this name by using the`-F` and`-R` options together on the`samfsck`(1M) command. For more information about the`sammkfs`(1M) command, see the`sammkfs`(1M) man page. For more information about the`samfsck`(1M) command, see the`samfsck`(1M) man page.

For lines that define an automated library and its associated drives, the lines defining the devices must contain the same Family Set name.

For a standalone, manually loaded removable media device, this field can contain a dash (-).

### The Device State Field

The Device State field specifies the state of the device when the file system is initialized. Valid device states are on and off. This is an optional field. If you do not want to enter on or off, enter a dash (-) character to indicate that this field is omitted.

### The Additional Parameters Field

For a Sun StorEdge SAM-FS file system, the Additional Parameters field is optional and can be left completely blank. By default, library catalog files are written to`/var/opt/SUNWsamfs/catalog/`family_set_name. Use this field if you want to specifiy an alternate path to the library catalog file.

For a Sun StorEdge QFS shared file system, this field must contain the keyword `shared`.

For a Sun StorEdge QFS unshared file system, enter a dash or leave this field blank.

##

Examples of`mcf` Files

Each file system configuration is unique. System requirements and actual hardware differ from site to site. The following sections show sample`mcf` files.

### Sun StorEdge SAM-FS Volume Management Example

For the Sun StorEdge SAM-FS file system, you can define family sets in the `/etc/opt/SUNWsamfs/mcf` file in the Equipment Type field using the following equipment types:

- `ms` for the Sun StorEdge SAM-FS file system type.

- `md` for the devices. Data is striped or round-robin across these devices. The stripe width is set with the`-o stripe=`n`` option on the`mount`(1M) command. The default stripe width is set based on the DAU size. For more information about stripe widths and DAU sizes, see File System Design.

Both metadata (including inodes, directories, allocation maps, and so on) and file data on Sun StorEdge SAM-FS file systems are located on the same disk. Data files are striped or round-robin through each disk partition defined within the same file system.

CODE EXAMPLE 3-2 shows an `mcf` file for a Sun StorEdge SAM-FS file system.

CODE EXAMPLE 3-2 Example `mcf` File for a Sun StorEdge SAM-FS File System
    # Sun StorEdge SAM-FS file system configuration example
    #
    # Equipment       Eq    Eq   Fam.  Dev.    Additional
    # Identifier      Ord  Type  Set   State   Parameters
    #-----------      ---   --  ------ ------  ------------------
    samfs1             10  ms  samfs1
    /dev/dsk/c1t1d0s6  11  md  samfs1  -
    /dev/dsk/c2t1d0s6  12  md  samfs1  -
    /dev/dsk/c3t1d0s6  13  md  samfs1  -
    /dev/dsk/c4t1d0s6  14  md  samfs1  -
    /dev/dsk/c5t1d0s6  15  md  samfs1  -

### Sun StorEdge QFS and Sun SAM-QFS Volume Management Examples

For the Sun StorEdge QFS and Sun SAM-QFS file systems, family sets are defined in the`/etc/opt/SUNWsamfs/mcf` file in the Equipment Type field using the following equipment types:

- `ma` for the Sun StorEdge QFS or Sun SAM-QFS file system type.

- `mm` for a metadata device. File data is not written to this device. You can specify multiple metadata devices. Metadata (including inodes, directories, allocation maps, and so on) on Sun StorEdge QFS and Sun SAM-QFS file systems is located on the metadata device(s) and is separated from the file data devices. By default, metadata is allocated using round-robin allocation if you have multiple metadata devices.

- `mr` or`md` for devices upon which file data is to be striped or round-robin.

- `g` XXX`` for devices upon which file data is to be striped as a group. A striped group is a logical group of devices that are striped as a unit. Data is striped across the members of each group.

Groups are specified with `g0` through `g127` equipment type numbers, with the stripe width on each device being the DAU. All devices in a striped group must be the same size. Different striped groups within one file system are not required to have the same number of members. `mr` and `g` XXX devices can be mixed in a file system, but `md` devices cannot be mixed with either `mr` or `g` XXX devices in a file system.

Data can be striped (if all groups contain the same number of devices) or round-robin between groups. The default is round robin.

Data files are striped or round-robin through each data disk partition (`mr` or`g` XXX) defined within the same file system.

#### Example 1

CODE EXAMPLE 3-3 shows an `mcf` file for a Sun StorEdge QFS or Sun SAM-QFS file system with two striped groups.

CODE EXAMPLE 3-3 Example `mcf` File Showing Striped Groups
    # Sun StorEdge QFS file system configuration
    #
    # Equipment       Eq   Eq    Fam.  Dev.    Additional
    # Identifier      Ord  Type  Set   State   Parameters
    #-----------      ---   --  ------ ------  ------------------
    qfs1               10   ma   qfs1    -
    /dev/dsk/c2t1d0s7  11   mm   qfs1    -
    /dev/dsk/c3t0d0s6  12   g0   qfs1    -
    /dev/dsk/c3t0d1s6  13   g0   qfs1    -
    /dev/dsk/c4t0d0s6  14   g1   qfs1    -
    /dev/dsk/c4t0d1s6  15   g1   qfs1    -

#### Example 2

CODE EXAMPLE 3-4 shows an `mcf` file with three Sun SAM-QFS file systems.

CODE EXAMPLE 3-4 Example `mcf` File Showing Three Sun SAM-QFS File Systems
    # Sun SAM-QFS file system configuration example
    #
    # Equipment       Eq    Eq   Fam.  Dev.    Additional
    # Identifier      Ord  Type  Set   State   Parameters
    #-----------      ---   --  ------ ------  ------------------
    qfs1               10  ma   qfs1   -
    /dev/dsk/c1t13d0s6 11  mm   qfs1   -
    /dev/dsk/c1t12d0s6 12  mr   qfs1   -
    #
    qfs2               20  ma   qfs2   -
    /dev/dsk/c1t5d0s6  21  mm   qfs2   -
    /dev/dsk/c5t1d0s6  22  mr   qfs2   -
    #
    qfs3               30  ma   qfs3   -
    /dev/dsk/c7t1d0s3  31  mm   qfs3   -
    /dev/dsk/c6t1d0s6  32  mr   qfs3   -
    /dev/dsk/c6t1d0s3  33  mr   qfs3   -
    /dev/dsk/c5t1d0s3  34  mr   qfs3   -

#### Example 3

CODE EXAMPLE 3-5 shows an`mcf` file with one Sun SAM-QFS file system that uses`md` devices. This`mcf` file also defines a tape library.

CODE EXAMPLE 3-5 Example `mcf` File Showing a Sun SAM-QFS File System and a Library
    # Sun SAM-QFS file system configuration example
    #
    # Equipment        Eq    Eq   Fam.  Dev.    Additional
    # Identifier       Ord  Type  Set   State   Parameters
    #-----------       ---   --  ------ ------  ----------
    samfs1             10    ma   samfs1  -
    /dev/dsk/c1t2d0s6  11    mm   samfs1  -
    /dev/dsk/c1t3d0s6  12    md   samfs1  -
    /dev/dsk/c1t4d0s6  13    md   samfs1  -
    /dev/dsk/c1t5d0s6  14    md   samfs1  -
    # scalar 1000 and 12 AIT tape drives
    /dev/samst/c5t0u0  30    rb   robot1  -
    /dev/rmt/4cbn     101    tp   robot1  on
    /dev/rmt/5cbn     102    tp   robot1  on
    /dev/rmt/6cbn     103    tp   robot1  on
    /dev/rmt/7cbn     104    tp   robot1  off
    /dev/rmt/10cbn    105    tp   robot1  on
    /dev/rmt/11cbn    106    tp   robot1  on
    /dev/rmt/3cbn     107    tp   robot1  on
    /dev/rmt/2cbn     108    tp   robot1  on
    /dev/rmt/1cbn     109    tp   robot1  on
    /dev/rmt/0cbn     110    tp   robot1  on
    /dev/rmt/9cbn     111    tp   robot1  on
    /dev/rmt/8cbn     112    tp   robot1  on

For more examples showing file system configuration in the`mcf` file, see the Sun StorEdge QFS and Sun StorEdge SAM-FS Software Installation and Configuration Guide.

##

Interactions Between File Settings, Options, and Directives

The`mcf` file defines each file system, but file system behavior depends on interactions between default systems settings, settings in the`/etc/vfstab` file, settings in the`samfs.cmd` file, and options on the`mount`(1M) command line.

You can specify some mount options, for example the stripe width, in more than one place. When this happens, settings in one place can override the settings in another.

For information about the various ways to specify mount options, see Mounting a File System.

##

Initializing a File System

The`sammkfs`(1M) command constructs new file systems, and its`-a` allocation_unit`` option allows you to specify the DAU setting. The number specified for allocation_unit determines the DAU setting.

The 4.2 releases of these file systems support two different superblock designs. Both superblock designs are available to you in the 4.2 release. In CODE EXAMPLE 3-6, the `samfsinfo`(1M) command output shows which superblock a file system is using.

CODE EXAMPLE 3-6 `samfsinfo` (1M) Command Example
    # samfsinfo samfs1
    name:     samfs1       version:        2
    time:     Wed Feb 21 13:32:18 1996
    count:    1
    capacity:      001240a0          DAU:         16
    space:         000d8ea0
    ord  eq   capacity      space   device
      0  10   001240a0   000d8ea0   /dev/dsk/c1t1d0s0

The first line of the preceding output indicates that this is a version 2 superblock. Be aware of the following operational and feature differences that pertain to these superblocks:

- Releases prior to 4.0 support only the version 1 superblock design.

- The 4.0 and later releases support the version 2 superblock. If you installed the 4.0 software as an upgrade, you must use the 4.0 or 4.2 `sammkfs`(1M) command to reinitialize your existing file systems before you attempt to use any of the features that depend on the version 2 superblock. Certain features, such as access control lists (ACLs) and the Sun StorEdge QFS shared file system, are supported only in the version 2 superblock. Reinitializing a file system is described as a step in the 4.2 software installation upgrade process, but you can do this any time after the software is installed.

| Caution - File systems that use a version 2 superblock cannot revert to a release prior to 4.0. You cannot use 4.2 release software to create a version 1 superblock.

For more information about features that require a version 2 superblock, or on using the`sammkfs`(1M) command to create the version 2 superblock, see the Sun StorEdge QFS and Sun StorEdge SAM-FS Software Installation and Configuration Guide.

#### Example

CODE EXAMPLE 3-7 shows using the `sammkfs`(1M) command to initialize a Sun StorEdge SAM-FS file system using a version 2 superblock.

CODE EXAMPLE 3-7 Initializing a File System with a Version 2 Superblock
    # sammkfs -a 64 samfs1
    Building 'samfs1' will destroy the contents of devices:
                    /dev/dsk/c1t9d0s2
                    /dev/dsk/c8t1d0s2
                    /dev/dsk/c8t5d0s2
                    /dev/dsk/c8t6d0s2
    Do you wish to continue? [y/N] y
    total data kilobytes       = 1715453952
    total data kilobytes free  = 1715453760
    total meta kilobytes       = 17684128
    total meta kilobytes free  = 17680304

For more information about the`sammkfs`(1M) command, see the`sammkfs`(1M) man page.

##

Configuration Examples

The rest of this chapter presents sample configurations and shows various steps and considerations in setting up the`mcf` file on a server. The following procedures are described:

- To Create a Sun StorEdge QFS Round-Robin Disk Configuration

- To Create a Sun StorEdge SAM-FS Round-Robin Disk Configuration

- To Create a Sun StorEdge QFS Striped Disk Configuration

- To Create a Sun StorEdge SAM-FS Striped Disk Configuration

- To Create a Sun StorEdge QFS Striped Groups Configuration

Note that all sample Sun StorEdge QFS configurations could have automated libraries and other removable media devices defined as well, essentially extending the file system beyond the size of the disk cache. Removable media device configurations are shown in only one example. For information about configuring removable media devices see the Sun StorEdge QFS and Sun StorEdge SAM-FS Software Installation and Configuration Guide.

The sample configurations assume that the file system is loaded on the system and all file systems are unmounted.

### To Create a Sun StorEdge QFS Round-Robin Disk Configuration

This sample configuration illustrates a Sun StorEdge QFS file system that separates the metadata onto a low-latency disk. Round-robin allocation is used on four partitions. Each disk is on a separate controller.

This procedure assumes the following:

- The metadata device is a single partition (`s6`) used on controller 5, logical unit number (LUN) 0 of the device designated as Equipment Ordinal 11.

- The data devices consist of four disks attached to four controllers.

1. Use an editor to create the`mcf` file.

CODE EXAMPLE 3-8 shows an example `mcf` file.

CODE EXAMPLE 3-8 Example Sun StorEdge QFS Round Robin `mcf` File
    # Sun StorEdge QFS disk cache configuration
    # Round-robin mcf example
    # Equipment       Eq   Eq    Fam.  Dev     Additional
    # Identifier      Ord  Type  Set   State   Parameters
    #-----------      ---   --  ------ ------  ------------------
    qfs1                1   ma   qfs1
    /dev/dsk/c5t0d0s6  11   mm   qfs1    on
    /dev/dsk/c1t1d0s6  12   mr   qfs1    on
    /dev/dsk/c2t1d0s6  13   mr   qfs1    on
    /dev/dsk/c3t1d0s6  14   mr   qfs1    on
    /dev/dsk/c4t1d0s6  15   mr   qfs1    on

2. Use the `mkdir`(1) command to create the `/qfs` mount point for the `/qfs1` file system.

For example:

    # mkdir /qfs

3. Use the `sammkfs`(1M) command to initialize the file system.

The following example uses the default 64-kilobyte DAU:

    # sammkfs qfs1

4. Use an editor to modify the`/etc/vfstab` file.

The Sun StorEdge QFS file system with`mr` data devices uses striped allocation as a default, so you must set`stripe=0` for round-robin allocation. To explicitly set round-robin on the file system, set the `stripe=0`, as follows:

    qfs1    -    /qfs    samfs    -    yes    stripe=0

5. Use the `mount`(1M) command to mount the file system.

For example:

    # mount /qfs

### To Create a Sun StorEdge SAM-FS Round-Robin Disk Configuration

This sample configuration illustrates a Sun StorEdge SAM-FS file system. Striped allocation is used by default on four partitions. You must set`stripe=0` to specify round-robin allocation. The file system is created using the`sammkfs`(1M) command. The data devices consist of four disks attached to four controllers. Each disk is on a separate controller.

1. Use an editor to create the `mcf` file.

CODE EXAMPLE 3-9 shows an example `mcf` file.

CODE EXAMPLE 3-9 Example Sun StorEdge SAM-FS Round Robin `mcf` File
    # Sun StorEdge SAM-FS disk cache configuration
    # Round-robin mcf example
    # Equipment       Eq   Eq    Fam.   Dev     Additional
    # Identifier      Ord  Type  Set    State   Parameters
    #-----------      ---   --  ------  ------  -----------------
    samfs1              1   ms   samfs1
    /dev/dsk/c1t1d0s6  11   md   samfs1  on
    /dev/dsk/c2t1d0s6  12   md   samfs1  on
    /dev/dsk/c3t1d0s6  13   md   samfs1  on
    /dev/dsk/c4t1d0s6  14   md   samfs1  on

2. Use the `mkdir`(1) command to create the `/samfs` mount point for the `/samfs1` file system.

For example:

    # mkdir /samfs

3. Use the `sammkfs`(1M) command to initialize the file system.

The default DAU is 16 kilobytes, but the following example sets the DAU size to 64 kilobytes:

    # sammkfs -a 64 samfs1

4. Use an editor to modify the `/etc/vfstab` file.

The Sun StorEdge SAM-FS file system uses striped allocation by default, so you must set `stripe=0` for round-robin allocation. To explicitly set round-robin on the file system, set the `stripe=0`, as follows:

    samfs1    -    /samfs    samfs    -    yes    stripe=0

5. Use the `mount`(1M) command to mount the file system.

For example:

    # mount /samfs

### To Create a Sun StorEdge QFS Striped Disk Configuration

This sample configuration illustrates a Sun StorEdge QFS file system. By default, file data is striped to four data partitions.

This procedure assumes the following:

- The metadata device is a single partition (`s6`) used on controller 0, LUN 1. Metadata is written to equipment 11 only.

- The data devices consist of four disks attached to four controllers. Each disk is on a separate controller.

1. Use an editor to create the `mcf` file.

CODE EXAMPLE 3-10 shows an example `mcf` file.

CODE EXAMPLE 3-10 Example Sun StorEdge QFS Striped Disk `mcf` File
    # Sun StorEdge QFS disk cache configuration
    # Striped Disk mcf example
    # Equipment       Eq   Eq    Fam.  Dev.    Additional
    # Identifier      Ord  Type  Set   State   Parameters
    #-----------      ---   --  ------ ------  ------------------
    qfs1               10   ma  qfs1
    /dev/dsk/c0t1d0s6  11   mm  qfs1     on
    /dev/dsk/c1t1d0s6  12   mr  qfs1     on
    /dev/dsk/c2t1d0s6  13   mr  qfs1     on
    /dev/dsk/c3t1d0s6  14   mr  qfs1     on
    /dev/dsk/c4t1d0s6  15   mr  qfs1     on

2. Use the `mkdir`(1) command to create the `/qfs` mount point for the `/qfs1` file system.

For example:

    # mkdir /qfs

3. Use the `sammkfs`(1M) command to initialize the file system.

The default DAU is 64 kilobytes, but the following example sets the DAU size to 128 kilobytes:

    # sammkfs -a 128 qfs1

With this configuration, any file written to this file system is striped across all of the devices in increments of 128 kilobytes.

4. Use an editor to modify the`/etc/vfstab` file.

The Sun StorEdge SAM-FS file system uses striped allocation by default. This example sets the stripe width as `stripe=1` DAU, which is the default. The following setting stripes data across all four of the `mr` devices with a stripe width of one DAU:

    qfs1    -    /qfs    samfs    -    yes    stripe=1

5. Use the `mount`(1M) command to mount the file system.

For example:

    # mount /qfs

### To Create a Sun StorEdge SAM-FS Striped Disk Configuration

This sample configuration illustrates a Sun StorEdge SAM-FS file system.

1. Use an editor to create the `mcf` file.

CODE EXAMPLE 3-11 shows an example `mcf` file. The data devices consist of four disks attached to four controllers. Each disk is on a separate LUN.

CODE EXAMPLE 3-11 Example Sun StorEdge SAM-FS Striped Disk `mcf` File
    # Sun StorEdge SAM-FS disk cache config
    # Striped Disk mcf example
    # Equipment       Eq   Eq    Fam.  Dev.    Additional
    # Identifier      Ord  Type  Set   State   Parameters
    #-----------      ---   --  ------ ------  ------------------
    samfs1             10   ms  samfs1
    /dev/dsk/c1t1d0s6  11   md  samfs1   on
    /dev/dsk/c2t1d0s6  12   md  samfs1   on
    /dev/dsk/c3t1d0s6  13   md  samfs1   on
    /dev/dsk/c4t1d0s6  14   md  samfs1   on

2. Use the `mkdir`(1) command to create the `/samfs` mount point for the `/samfs1` file system.

For example:

    # mkdir /samfs

3. Use the `sammkfs`(1M) command to initialize the file system.

The following example uses the default 16-kilobyte DAU:

    # sammkfs samfs1

With this striped disk configuration, any file written to this file system is striped across all of the devices in increments of 16 kilobytes.

4. Use an editor to modify the`/etc/vfstab` file.

Specify the mount point for this file system in `/etc/vfstab`.

5. Use the `mount`(1M) command to mount the file system.

For example:

    # mount /samfs

### To Create a Sun StorEdge QFS Striped Groups Configuration

Striped groups allow you to group RAID devices together for very large files. A DAU is represented by one bit in the bit maps. If the striped group has n devices, n multiplied by the DAU is the minimum allocation. Only one bit in the bit maps is used to represent n X DAU. This method of writing huge DAUs across RAID devices saves bit map space and system update time. Striped groups are useful for writing very large files to a group of RAID devices and for streaming large amounts of data to and from disk.

Note - The minimum disk space allocated in a striped group is as follows: minimum_disk_space_allocated = DAU x number_of_disks_in_the_group Writing a single byte of data fills the entire minimum disk space allocated in a striped group. Striped groups are used for very specific applications. Make sure that you understand the effects of using striped groups with your file system.

Files with lengths less than the aggregate stripe width times the number of devices (in this example, files less than 128 kilobytes x 4 disks = 512 kilobytes in length) still use 512 kilobytes of disk space. Files larger than 512 kilobytes have space allocated for them as needed in total space increments of 512 kilobytes.

The devices within a striped group must be the same size. It is not possible to add devices to increase the size of a striped group. You can use the`samgrowfs`(1M) command to add additional striped groups, however. For more information about this command, see the`samgrowfs`(1M) man page.

This sample configuration illustrates a Sun StorEdge QFS file system that separates the metadata onto a low-latency disk. Two striped groups are set up on four drives.

This procedure assumes the following:

- The metadata device is a single partition (`s6`) used on controller 0, LUN 1.

- The data devices consist of four disks (two groups of two identical disks) attached to four controllers. Each disk is on a separate LUN. The entire disk is used for data storage, assuming that partition 6 occupies the entire disk.

1. Use an editor to create the `mcf` file.

CODE EXAMPLE 3-12 shows an example `mcf` file.

CODE EXAMPLE 3-12 Example Sun StorEdge QFS Striped Group `mcf` File
    # Sun StorEdge QFS disk cache configuration
    # Striped Groups mcf example
    # Equipment       Eq   Eq    Fam.  Dev.    Additional
    # Identifier      Ord  Type  Set   State   Parameters
    #-----------      ---   --  ------ ------  ------------------
    qfs1               10   ma  qfs1
    /dev/dsk/c0t1d0s6  11   mm  qfs1     on
    /dev/dsk/c1t1d0s6  12   g0  qfs1     on
    /dev/dsk/c2t1d0s6  13   g0  qfs1     on
    /dev/dsk/c3t1d0s6  14   g1  qfs1     on
    /dev/dsk/c4t1d0s6  15   g1  qfs1     on

2. Use the `mkdir`(1) command to create the `/qfs` mount point for the `/qfs1` file system.

For example:

    # mkdir /qfs

3. Use the `sammkfs`(1M) command to initialize the file system.

The following example sets the DAU size to 128 kilobytes:

    # sammkfs -a 128 qfs1

4. Use an editor to modify the`/etc/vfstab` file.

The following example uses the default setting of `stripe=0`, which essentially specifies a round-robin allocation from striped group `g0` to striped group `g1`:

     qfs1    -    /qfs    samfs    -    yes   stripe=0

This `/etc/vfstab` file sets the stripe width using the `stripe=` option. In this example, there are two striped groups, `g0` and `g1`. With the `stripe=0` specification, devices 12 and 13 are striped, and files are round-robin around the two striped groups. You are really treating a striped group as a bound entity. That is, you cannot change the configuration of the striped group, after it is created, without issuing another `sammkfs`(1M) command.

5. Use the `mount`(1M) command to mount the file system.

For example:

    # mount /qfs

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