Provided by: nbdkit_1.16.2-1ubuntu3_amd64
nbdkit-delay-filter - nbdkit delay filter
nbdkit --filter=delay plugin rdelay=SECS wdelay=SECS [plugin-args...] nbdkit --filter=delay plugin rdelay=NNms wdelay=NNms [plugin-args...] nbdkit --filter=delay plugin [plugin-args ...] delay-read=(SECS|NNms) delay-write=(SECS|NNms) delay-zero=(SECS|NNms) delay-trim=(SECS|NNms) delay-extents=(SECS|NNms) delay-cache=(SECS|NNms) delay-fast-zero=BOOL
"nbdkit-delay-filter" is a filter that delays read and write requests by some seconds or milliseconds. This is used to simulate a slow or remote server, or to test certain kinds of race conditions in Linux. To limit server bandwidth use nbdkit-rate-filter(1) instead.
Delays reads and writes by 100ms: nbdkit --filter=delay file disk.img rdelay=100ms wdelay=100ms Delay only zero operations by 1 second, nothing else is affected: nbdkit --filter=delay file disk.img delay-zero=1
rdelay=SECS rdelay=NNms delay-read=SECS delay-read=NNms Delay read operations by "SECS" seconds or "NN" milliseconds. The two forms "rdelay" and "delay-read" work identically. delay-write=SECS delay-write=NNms Delay write operations by "SECS" seconds or "NN" milliseconds. delay-zero=SECS delay-zero=NNms Delay zero operations by "SECS" seconds or "NN" milliseconds. See also delay-fast- zero. delay-trim=SECS delay-trim=NNms Delay trim/discard operations by "SECS" seconds or "NN" milliseconds. delay-extents=SECS delay-extents=NNms Delay block status (extents) operations by "SECS" seconds or "NN" milliseconds. delay-cache=SECS delay-cache=NNms Delay advisory cache operations by "SECS" seconds or "NN" milliseconds. wdelay=SECS wdelay=NNms Delay write, zero and trim operations by "SECS" seconds or "NN" milliseconds. delay-fast-zero=BOOL The NBD specification documents an extension called fast zero, in which the client may request that a server should reply with "ENOTSUP" as soon as possible if the zero operation offers no real speedup over a corresponding write. By default, this parameter is true, and fast zero requests are serviced by the plugin after the same delay as any other zero request; but setting this parameter to false instantly fails a fast zero response without waiting for or consulting the plugin.
$filterdir/nbdkit-delay-filter.so The filter. Use "nbdkit --dump-config" to find the location of $filterdir.
"nbdkit-delay-filter" first appeared in nbdkit 1.2, based on earlier "rdelay" and "wdelay" options in nbdkit-file-plugin(1).
nbdkit(1), nbdkit-filter(3), nbdkit-rate-filter(1).
Richard W.M. Jones
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