device-mapper: error adding target to table

device-mapper: table: 253:0: multipath: error getting device
device-mapper: ioctl: error adding target to table

1. When multipath/multipathd starts you might see a message(s) like

     device-mapper: table: 253:0: multipath: error getting device
     device-mapper: ioctl: error adding target to table

• in console or /var/log/messages. This is due to dm-multipath trying to create multipath devices for your root device and/or other devices that are already mounted or opened.

• You can avoid this by adding a blacklist stanza in your /etc/multipath.conf file for those devices that generate these errors.

附：

2.3. Configuration File (/etc/multipath.conf)

DM-Multipath allows many of the feature to be user configurable using the configuration file /etc/multipath.conf. multipath command and multipathd uses the configuration information from this file. This file is consulted only during the configuration of multipath devices. In other words, if the user makes any changes to this file, then the multipath command need to be rerun to configure the multipath devices (i.e the user has to do multipath -F followed by multipath).

Support for many of the devices (as listed below) is inbuilt in the user space component of DM-Multipath. If the support for a specific storage device is not inbuilt or the user wants to override some of the values only then the user need to modify this file.

This file has 5 sections:

1. System level defaults ("defaults"): Where the user can specify system level default override.

2. Black listed devices ("blacklist"): User can specify the list of devices they do not want to be under the control of DM-Multipath. These devices will be excluded.

3. Black list exceptions ("blacklist_exceptions"): Specific devices to be treated as multipath candidates even if they exist in the blacklist.

4. Storage controller specific settings ("devices"): User specified configuration settings will be applied to devices with specified "Vendor" and "Product" information.

5. Device specific settings ("multipaths"): User can fine tune configuration settings for individual LUNs.

User can specify the values for the attributes in this file using regular expression syntax.

For detailed explanation of the different attributes and allowed values for the attributes please refer to multipath.conf.annotated file.

• In Mainline, this file is located in the root directory of multipath-tools.

• In RedHat, this file is located in the directory /usr/share/doc/device-mapper-multipath-X.Y.Z/.

• In SuSE, this file is located in the directory /usr/share/doc/packages/multipath-tools/

2.3.1. Attribute value overrides

Attribute values are set at multiple levels (internally in multipath tools and through multipath.conf file). Following is the order in which the attribute values will be overwritten.

1. Global internal defaults, as specified in the man page of multipath.conf.
2. Device specific internal defaults, as defined in libmultipath/hwtable.c.
3. Items described in defaults section of /etc/multipath.conf.
4. Items defined in device section of /etc/multipath.conf.

   • Note that this will completely overwrite configuration information defined in (2) above. So, if even if you want to change/add only one attribute one have to provide the whole list for a device.

5. Items defined in multipaths section of /etc/multipath.conf.

from:

http://sources.redhat.com/lvm2/wiki/MultipathUsageGuide

http://sources.redhat.com/lvm2/wiki/MultipathUsageGuide#blacklist