MD Recovery Kit – Known Issues / Restrictions

MD Kit does not support mirrors created with “homehost”

The LifeKeeper MD Recovery Kit will not work properly with a mirror created with the “homehost” feature. Where “homehost” is configured, LifeKeeper will use a unique ID that is improperly formatted such that in-service operations will fail. On SLES 11 systems, the “homehost” will be set by default when a mirror is created. The version of mdadm that supports “homehost” is expected to be available on other distributions and versions as well. When creating a mirror, specify —homehost=”“ on the command line to disable this feature. If a mirror already exists that has been created with the “homehost” setting, the mirror must be recreated to disable the setting. If a LifeKeeper hierarchy has already been built for a mirror created with “homehost”, the hierarchy must be deleted and recreated after the mirror has been built with the “homehost” disabled.

MD Kit does not support MD devices created on LVM devices

The LifeKeeper MD Recovery Kit will not work properly with an MD device created on an LVM device. When the MD device is created, it is given a name that LifeKeeper does not recognize.

MD Kit configuration file entries in /etc/mdadm.conf not commented out

The LifeKeeper configuration file entries in /etc/mdadm.conf should be commented out after a reboot. These file entries are not commented out.

Local recovery not performed in large configurations

In some cases with large configurations (6 or more hierarchies), if a local recovery is triggered (sendevent), not all of the hierarchies are checked resulting in local recovery attempt failures.

Mirrors automatically started during boot

On some systems (for example those running RHEL 6), there is an AUTO entry in the configuration file (/etc/mdadm.conf) that will automatically start mirrors during boot (example: AUTO +imsm +1.x –all).

Solution: Since LifeKeeper requires that mirrors not be automatically started, this entry will need to be edited to make sure that LifeKeeper mirrors will not be automatically started during boot. The previous example (AUTO +imsm +1.x –all) is telling the system to automatically start mirrors created using imsm metadata and 1.x metadata minus all others. This entry should be changed to “AUTO -all”, telling the system to automatically start everything “minus” all; therefore, nothing will be automatically started.

Important: If system critical resources (such as root) are using MD, make sure that those mirrors are started by other means while the LifeKeeper protected mirrors are not.