New `property` parameter supported in `blacklist` and `blacklist_exception` sections of `multipath.conf`
The `multipath.conf` configuration file now supports the `property` parameter in the `blacklist` and `blacklist_exception` sections of the file. This parameter allows users to blacklist certain types of devices. The `property` parameter takes a regular expression string that is matched against the `udev` environment variable names for the device.
The `property` parameter in `blacklist_exception` works differently than the other `blacklist_exception` parameters. If the parameter is set, the device must have a `udev` variable that matches. Otherwise, the device is blacklisted.
Most usefully, this parameter allows users to blacklist SCSI devices that multipath should ignore, such as USB sticks and local hard drives. To allow only SCSI devices that could reasonably be multipathed, set this parameter to `(SCSI_IDENT_|ID_WWN)` in the `blacklist_exceptions` section of the `multipath.conf` file.
Upstream multipath allows a "property" blacklist option that blacklists devices with certain udev environment variables. It also allows "property" as a blacklist_exceptions option. The blacklist_exceptions option is special. If an exceptions option is set, but no blacklist option, it is assumed that all devices are blacklisted, except the ones that have udev evironment variables that match the exception option.
RHEL multipath should include this feature, and have the default multipath.conf file installed by mpathconf set
blacklist_exceptions {
property "(SCSI_IDENT_|ID_WWN)"
}
which is the upstream default. This has the effect of keeping multipath from running a number of local devices that it has not business attempting to multipath.
Backported the upstream feature as described in the problem description, with one exception. mpathconf does not set the property blacklist exception by default. If you need it set, you must set it yourself.
Ben:
I edited your release note description by moving around some text. Could you look this over and let me know if this is correct as it now stands?
Steven
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHEA-2018:0884
Upstream multipath allows a "property" blacklist option that blacklists devices with certain udev environment variables. It also allows "property" as a blacklist_exceptions option. The blacklist_exceptions option is special. If an exceptions option is set, but no blacklist option, it is assumed that all devices are blacklisted, except the ones that have udev evironment variables that match the exception option. RHEL multipath should include this feature, and have the default multipath.conf file installed by mpathconf set blacklist_exceptions { property "(SCSI_IDENT_|ID_WWN)" } which is the upstream default. This has the effect of keeping multipath from running a number of local devices that it has not business attempting to multipath.