----------
*start* [-BdqrRf] [-c <ioprio_class> -n <ioprio_classdata>] <path>|<device>::
Start a scrub on all devices of the filesystem identified by <path> or on
-a single <device>.
+a single <device>. If a scrub is already running, the new one fails.
+
Without options, scrub is started as a background process.
Progress can be obtained with the *scrub status* command. Scrubbing
-n <ioprio_classdata>::::
Set IO priority classdata (see `ionice`(1) manpage).
-f::::
-force to check whether scrub has started or resumed in userspace.
-this is useful when scrub stat record file is damaged.
+Force starting new scrub even if a scrub is already running.
+This is useful when scrub stat record file is damaged.
*cancel* <path>|<device>::
If a scrub is running on the filesystem identified by <path>, cancel it.
static const char * const cmd_scrub_start_usage[] = {
"btrfs scrub start [-BdqrRf] [-c ioprio_class -n ioprio_classdata] <path>|<device>",
- "Start a new scrub",
+ "Start a new scrub. If a scrub is already running, the new one fails.",
"",
"-B do not background",
"-d stats per device (-B only)",
"-R raw print mode, print full data instead of summary"
"-c set ioprio class (see ionice(1) manpage)",
"-n set ioprio classdata (see ionice(1) manpage)",
- "-f force to skip checking whether scrub has started/resumed in userspace ",
+ "-f force starting new scrub even if a scrub is already running.",
" this is useful when scrub stats record file is damaged",
NULL
};