PRIMECLUSTER Global Disk Services Configuration and Administration Guide 4.1 (Linux)
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Appendix D Command Reference

D.3 sdxgroup - Group operations

SYNOPSIS

sdxgroup -C -c class -h hgroup -l lgroup,...
[ -a attribute=value[,attribute=value]] [-e delay=msec ]

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

sdxgroup -R -c class -g group

 

DESCRIPTION

Use sdxgroup to perform operations on group objects (excluding shadow groups).
You must be superuser to use this command.

 

PRIMARY OPTIONS

You can use one of the following options.

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

When no group with the same name as hgroup exists, a group will be created automatically.

Groups specified by hgroup are referred to as higher level group, and groups specified by lgroup are referred to as lower level group.

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

You cannot connect groups when:

- lgroup is a mirror group or a switch group
- hgroup is a concatenation group or a switch group
- type attributes of lgroup and hgroup are the same

A group that already contains volumes cannot be connected to another group.
Connecting a group to a mirror group and a stripe group is explained below.

- When connecting to a mirror group
You can connect one or more groups (stripe group or concatenation group) specified by lgroup,... to hgroup which is a mirror group.

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

When one or more volumes already exist within the mirror group specified by hgroup, the slice configuration of disk or lower level group that is already connected to hgroup will be automatically copied to the newly connected lgroup. Also, when there is an activated volume within hgroup, volume data in addition to the slice configuration will be automatically copied upon returning from the sdxgroup command, therefore increasing the mirroring multiplexity.

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

- When connecting to a stripe group
You can connect one or more groups (concatenation group) specified by lgroup,... to hgroup which is a stripe group. Groups specified by lgroup,..., will be connected to hgroup in the order they are listed.

Disks and lower level groups connected to the same stripe group will each configure a stripe column, and will be striped in the order they are connected. When only one disk or one lower level group is connected, a volume cannot be created within that stripe group. When striping "n" number of columns, "n" number of disks or lower level groups must be connected. A minimum of two columns and a maximum of 64 columns are supported.

When a stripe group specified by hgroup already exists, stripe columns will be added after the stripe columns that already exist in hgroup, in the order they are specified by lgroup,... However, you cannot increase the stripe columns by connecting groups to stripe groups with volumes, or to stripe groups connected to a higher level group.

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

 

-D
Disconnect
Disconnects group specified by lgroup from the higher level group hgroup. The class indicates class name to which lgroup belongs, and hgroup indicates the higher level group name 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 group, disconnection will result in an error. In such case, disconnect hgroup from its higher level group, and then disconnect lgroup.

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

Conditions on when you cannot disconnect a group from a mirror group or a stripe group are explained below.

- When disconnecting from a mirror group
For example, you cannot disconnect lgroup from a mirror group if one or more volumes exist within the mirror group specified by hgroup, and lgroup is the only object connected to hgroup.

- When disconnecting from a stripe group
You cannot disconnect a lower level group from a stripe group with one or more existing volumes, or from a stripe group connected to a higher level group.

 

-R
Remove
Remove the group definition specified by group. The class indicates the class name to which group belongs.

Disks and lower level groups connected to group will be disconnected. The disconnected disk's attribute will return to its original setting (single disk or undefined disk).

group cannot be removed when one or more volumes exist within group, or when group is connected to a higher level 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 group hgroup is automatically created. Using this option sets the attribute of the created hgroup to value.

The attribute indicates the attribute name, and value indicates the attribute value. Always separate attribute and value with an equal (=) sign. When indicating multiple attributes, specifiers should be combined using commas(,) as the delimiter.

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

You can indicate the following combination to attribute and value.
If multiple attributes are indicated and an error results because of any part of them, the entire process is canceled.

type=mirror or type=stripe (default is mirror)
Sets the type attribute of hgroup.
mirror
Sets type attribute to "mirror."
stripe
Sets type attribute to "stripe."
width=blks (default is 32)
Sets the stripe width of hgroup. The blks indicates the stripe width in block number (base 10). One block is 512 bytes. For blks, you can indicate an integer that is two raised to the power (one and larger), which is equal to or smaller than the available size of the smallest group specified by lgroup,... If hgroup is not a stripe group, this option will result in an error.
-c class
The class indicates the class name to which the group belongs, where group is the target of the operation.

 

-e delay=msec (when using -C)
When a group is connected to a mirror group, data contained in the volume will be copied as needed. This option delays the issuing of the input/output request to the disk by milliseconds specified by msec, allowing adjustment for the effect on the application accessing the volume. Default is 0. Values from 0 to 1000 may be specified for msec.
If hgroup is not a mirror group, this option is ignored.

 

-g group (when using -R)
The group indicates the group name that is the target of the operation.

 

-h hgroup (when using -C,-D)
The hgroup indicates the higher level group name to which the lower level group is connected or is to be connected, where the lower level group is the target of the operation.

 

-l lgroup (when using -D)
The lgroup indicates the lower level group name that is the target of the operation.

 

-l lgroup,... (when using -C)
The lgroup indicates the lower level group name that is the target of the operation. To connect multiple groups, separate each group name with a comma (,) as the delimiter.

RETURNED VALUE

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


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