Man1 - ndctl-wait-scrub.1

ndctl-wait-scrub - wait for an Address Range Scrub (ARS) operation to complete

  ndctl wait-scrub [<bus-id> <bus-id2> ... <bus-idN>] [<options>]

NVDIMM Address Range Scrub is a capability provided by platform firmware that allows for the discovery of memory errors by system software. It enables system software to pre-emptively avoid accesses that could lead to uncorrectable memory error handling events, and it otherwise allows memory errors to be enumerated.

The kernel provides a POLL(2) capable sysfs file (scrub) to indicate the state of ARS. The scrub file maintains a running count of ARS runs that have taken place. While a current run is in progress a + character is emitted along with the current count. The ndctl wait-scrub operation waits for scrub, across all specified buses, to indicate not in-progress at least once.

Wait for scrub on all nvdimm buses in the system. The json listing report at the end only includes the buses that support ARS operations.

    # ndctl wait-scrub
    [
      {
        "provider":"nfit_test.1",
        "dev":"ndbus3",
        "scrub_state":"idle"
      },
      {
        "provider":"nfit_test.0",
        "dev":"ndbus2",
        "scrub_state":"idle"
      }
    ]

When specifying an individual bus, or if there is only one bus in the system, the command reports whether ARS support is available.

    # ndctl wait-scrub e820
    error waiting for scrub completion: Operation not supported

-v, –verbose

Emit debug messages for the ARS wait process

Copyright © 2016 - 2020, 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.

ndctl-start-scrub(1), “ACPI http://www.uefi.org/sites/default/files/resources/ACPI%206_2_A_Sept29.pdf 6.2 Specification Section 9.20.7.2 Address Range Scrubbing (ARS) Overview“