Which command is used to change the reserve policy of a disk?

The `chdev` command modifies device attributes in AIX's Object Data Manager (ODM). The reserve policy of a disk is stored as a device attribute and is changed using `chdev -l <diskname> -a reserve_policy=<value>`, which can set it to no_reserve, single_path, or PR_shared among others.

`chpv` modifies physical volume characteristics within a volume group such as mirror pool assignment and active/inactive state, but does not manage the disk device's reserve policy attribute.

`chvg` modifies volume group-level attributes such as quorum settings, maximum physical partitions, or big VG format, not individual disk device attributes.

`chattr` modifies extended attributes of files and directories in the filesystem, not physical disk device configuration attributes.