PRIMECLUSTER Global Disk Services Configuration and Administration Guide 4.1 (Solaris(TM) Operating System)

D.16 sdxshadowgroup - Shadow group operations

SYNOPSIS

sdxshadowgroup -C -c class -h hgroup -l lgroup,...
[-a attribute=value[,attribute=value]]

sdxshadowgroup -D -c class -h hgroup -l lgroup

sdxshadowgroup -R -c class -g group

 

DESCRIPTION

Use sdxshadowgroup to perform operations on shadow groups.
This command can be executed with superuser access privileges only.

 

PRIMARY OPTIONS

You have a choice of the following options.

-C

Connect

Connects one or more shadow groups (stripe type or concatenation type) specified by lgroup,... to a shadow group (mirror type or stripe type) specified by hgroup. class indicates the name of the shadow class to which lgroup belongs.

When no shadow group with the same name as hgroup exists, it is created automatically.

A shadow group specified by hgroup is referred to as a higher level shadow group, and a shadow group specified by lgroup is referred to as a lower level shadow group.

Lower level shadow groups and shadow disks connected to the same higher level shadow group are mirrored or striped according to the type attribute of the higher level shadow group. Connecting a shadow group to a higher level shadow group does not change the type attribute of the lower level shadow group.

You cannot connect shadow groups when:
- lgroup is the mirror group.
- hgroup is the concatenation group.
- Type attributes of lgroup and hgroup are the same.

In addition, a shadow group already including a shadow volume cannot be connected to another shadow group.

Details about connecting shadow groups to mirror type and stripe type shadow groups are described below.

- When connecting to a shadow group of the mirror type

One or more shadow groups (stripe type or concatenation type) specified by lgroup,... can be connected to a shadow group of the mirror type specified by hgroup.

Shadow disks and lower level shadow groups connected to the same shadow group of the mirror type will be mirrored one another. When only one shadow disk or one lower level shadow group is connected, the shadow volume created within that shadow group of the mirror type will not be mirrored. When configuring a mirroring environment with "n"-way multiplexing, "n" numbers of shadow disks or lower level shadow groups must be connected. A maximum of eight-way multiplex mirroring is supported.

If a lower level shadow group is connected to a shadow group of the mirror type with a shadow volume, synchronization copying for the shadow volume is not performed. To ensure synchronization for a shadow volume of the mirror type, the mirror volume must be properly synchronized with GDS or SynfinityDisk that manages the mirror volume corresponding to the shadow volume.

The available size of a shadow group of the mirror type (available capacity as shadow volumes) will be the same as that of the smallest shadow disk or lower level shadow group connected. If connecting lgroup decreases the available size of hgroup, a warning message will be sent to standard error output.

- When connecting to a shadow group of the stripe type

One or more shadow groups (concatenation type) specified by lgroup,... can be connected to a shadow group of the stripe type indicated by hgroup. Shadow groups indicated by lgroup,... will be connected to hgroup in the order they are listed. Lower level groups connected to a stripe group in another domain should be connected in the same order. Alternatively, destination disks copied with the copy functions of disk units from lower level groups connected to a stripe group should be connected in the same order. For the order of connecting lower level groups, check the DISKS field displayed with the sdxinfo -G command.

Respective shadow disks and lower level shadow groups connected to the same shadow group of the stripe type will configure stripe columns, and will be striped in the order they were connected. When only one shadow disk or one lower level shadow group is connected, a shadow volume cannot be created within that shadow group. When striping "n" number of columns, "n" number of shadow disks or lower level shadow groups must be connected. Striping of two or more columns up to 64 columns is supported.

When a shadow group of the stripe type indicated by hgroup already exists, stripe columns will be added after the existing stripe columns in hgroup, in the order they are indicated by lgroup,... However, a shadow group with the available size smaller than the stripe width cannot be connected to an existing shadow group of the stripe type. In addition, you cannot increase stripe columns by connecting shadow groups to a stripe group with a shadow volume, or to a stripe group connected to a higher level shadow group.

The available size of a shadow group of the stripe type (available capacity as shadow volumes) equals the available size of the smallest shadow disk (or the lower level shadow group) connected multiplied by the number of stripe columns, and rounded down to the common multiple of the stripe width times stripe columns and the cylinder size. If connecting lgroup decreases the available size of hgroup, a warning message will be sent to standard error output.

 

-D

Disconnect

Disconnects a shadow group specified by lgroup from a shadow group specified by hgroup. class indicates the name of the shadow class to which lgroup belongs, and hgroup indicates the name of the higher level shadow group to which lgroup is connected.

When lgroup is the only object connected to hgroup, hgroup will automatically be removed upon disconnecting lgroup. However, when lgroup is the only object connected to hgroup, and hgroup is connected to a higher level shadow group, disconnection will result in an error. In such a case, disconnect hgroup from its higher level shadow group, and then disconnect lgroup.

You cannot disconnect lgroup if the disconnection may result in a change in the status of any existing shadow volume within hgroup.

Conditions that do not allow you to disconnect a shadow group from a shadow group of the mirror type or a shadow group of the stripe type are as below.

- When disconnecting from a higher level shadow group of the mirror type

For example, you cannot disconnect lgroup from a shadow group of the mirror type specified by hgroup if a shadow volume exists within that group, and lgroup is the only object connected to hgroup.

- When disconnecting from a shadow group of the stripe type

You cannot disconnect a lower level shadow group from a shadow group of the stripe type with an existing shadow volume, or from a shadow group of the stripe type connected to a higher level shadow group.

 

-R

Remove

Removes the shadow group definition specified by group. class indicates the name of the shadow class to which group belongs.

Shadow disks and lower level shadow groups connected to group will be disconnected. The disconnected shadow disk will have the original type attribute (single or undefined).

The definition cannot be removed when a shadow volume exists within group, or when group is connected to a higher level shadow group.

 

SUB OPTIONS

Sub options are as follows:

-a attribute=value[,attribute=value] (when using -C)

When using the -C option and defining a new group name with the -h option, a new shadow group, hgroup, is automatically created. This option sets attribute to value for the created hgroup attribute.

attribute indicates the attribute name, and value indicates the attribute value. An equal sign (=) is always necessary between attribute and value. When specifying multiple attributes, each specifier must be separated by a comma (,).

If no shadow group is created, specifying an attribute value different from the attribute value of the existing hgroup will result in an error. You cannot change the attribute value of an existing hgroup.

You can specify one of the following combinations to attribute and value.

If multiple attributes are specified and any error occurs, the entire process is canceled.

type=mirror or type=stripe (default is mirror)

Sets the type attribute of hgroup.

mirror

Sets the type attribute to "mirror".

stripe

Sets the type attribute to "stripe".

width=blks (default is 32)

Sets the stripe width of hgroup. blks indicates the stripe width in blocks (decimal numbers). One block is 512 bytes. For blks, you can specify an integer that is the power of two, equal to or larger than one and equal to or smaller than the available size of the smallest shadow group among groups specified by lgroup,... If hgroup is not the stripe type, this option will cause an error.

 

-c class

class indicates the name of the shadow class to which the shadow group as the object of the operation belongs.

 

-g group (when using -R)

group indicates the name of the shadow group that is the object of the operation.

 

-h hgroup (when using -C,-D)

hgroup indicates the name of the higher level shadow group to which the lower level shadow group as the object of the operation is connected or is to be connected.

 

-l lgroup (when using -D)

lgroup indicates the name of the lower level shadow group as the object of the operation.

 

-l lgroup,... (when using -C)

lgroup indicates the name of the lower level shadow group as the object of the operation. To connect multiple shadow groups, separate each group name with a comma (,).

RETURNED VALUE

Upon successful completion, a value of 0 is returned.
Otherwise, a non-zero value is returned.