NAME

       ndctl-clear-errors - clear all errors (badblocks) on the given namespace

SYNOPSIS

       ndctl clear-errors <namespace> [<options>]

DESCRIPTION

       A namespace may have one or more media errors, either known to the kernel or in a latent
       state. These error locations, or badblocks can cause poison consumption events if read in
       an unsafe manner.

       Moreover, these badblocks also indicate that due to media corruption, any data that may
       have been in these locations has been unrecoverably lost.

       Normally, in the presence of such errors, the administrator is expected to recover the
       data from out of band means (such as backups), destroy the namespace, recreate it, and
       then restore the data. When the data is re-written, the writes will allow any errors to be
       cleared as they are encountered. In such a workflow, one should never need to use the
       clear-errors command.

       However, there may be special use cases, where the data currently on the namespace does
       not matter - for example, if a devdax mode namespace is being prepared for use as
       system-ram. In such cases, it may be desirable to clear any errors on the namespace prior
       to switching its mode to prevent disruptive machine checks due to poison consumption.

           Note
           Only use this command when the data on the namespace is immaterial. For any blocks
           that are cleared via this command, any data on the blocks in question will be lost,
           and replaced with content that is implementation (platform) defined, and
           unpredictable.

           Warning
           This is a DANGEROUS command, and should only be used after fully understanding its
           implications and consequences. This WILL erase your data.

       For namespaces in one of fsdax or devdax modes, this command will only consider the data
       area for error clearing. Namespace metadata, such as info-blocks, will not be touched. For
       namespaces in raw mode, the full available capacity of the namespace is considered for
       error clearing. Namespaces that are in sector mode are not supported, and will be skipped.

           Note
           It is expected that the command is run with the namespace enabled. A namespace in the
           disabled state will appear as, and will be treated as a raw namespace, and error
           clearing will be performed for the full available capacity of the namespace, including
           any potential metadata areas. If there happen to be errors in the metadata area,
           clearing them may result in unpredictable outcomes. You have been warned!

       Known errors are ones that the kernel has encountered before, either via a previous scrub,
       or by an attempted read from those locations. These can be listed by running ndctl list
       --media-errors for a given namespace. Latent errors, as the name indicates, are unknown to
       the kernel. These can be found by running a scrub operation on the NVDIMMs in question. By
       default, the ndctl-clear-errors command only clears known errors. This can be overridden
       using the --scrub option to clear all errors.

           Note
           If a scrub is in progress when the command is called, it will unconditionally wait for
           it to complete.

EXAMPLES

       Clear errors on namespace 0.0

           ndctl clear-errors namespace0.0

       Clear errors on all namespaces belonging to region1, including scrubbing for latent errors

           ndctl clear-errors --scrub --region=region1 all

OPTIONS

       -s, --scrub
           Perform a scrub on the bus prior to clearing errors. This allows for the clearing of
           any latent media errors in addition to errors the kernel already knows about.

           Note
           This will cause the command to start and wait for a full scrub, and this can
           potentially be a very long-running operation.

       -v, --verbose
           Emit debug messages.

       -r, --region=
           A regionX device name, or a region id number. Restrict the operation to the specified
           region(s). The keyword all can be specified to indicate the lack of any restriction,
           however this is the same as not supplying a --region option at all.

       -b, --bus=
           A bus id number, or a provider string (e.g. "ACPI.NFIT"). Restrict the operation to
           the specified bus(es). The keyword all can be specified to indicate the lack of any
           restriction, however this is the same as not supplying a --bus option at all.

COPYRIGHT

       Copyright (c) 2016 - 2019, Intel Corporation. License GPLv2: GNU GPL version 2
       http://gnu.org/licenses/gpl.html. This is free software: you are free to change and
       redistribute it. There is NO WARRANTY, to the extent permitted by law.

SEE ALSO

       ndctl-start-scrub(1), ndctl-list(1)