nbdkit-noextents-filter - disable extents in the underlying plugin
nbdkit --filter=noextents plugin“Extents” are a feature of the NBD protocol / nbdkit which allow the client to detect sparse regions of the underlying disk. nbdkit-noextents-filter disables this so that the plugin appears to be fully allocated, at least to a client that requests structured replies. It is also possible to use the --no-meta-contexts or --no-sr options to nbdkit to prevent the client from negotiating extents at all, but that is accompanied by more side effects than this filter.
This filter can be useful when combined with nbdkit-file-plugin(1) serving a file from a file system known to have poor lseek(2) performance (tmpfs is known to be one such system).
There are no parameters specific to nbdkit-noextents-filter. Any parameters are passed through to and processed by the underlying plugin in the normal way.
The filter.
Use nbdkit --dump-config to find the location of $filterdir.
nbdkit-noextents-filter first appeared in nbdkit 1.14.
nbdkit(1), nbdkit-filter(3), nbdkit-extentlist-filter(1), nbdkit-fua-filter(1), nbdkit-multi-conn-filter(1), nbdkit-nocache-filter(1), nbdkit-noparallel-filter(1), nbdkit-nozero-filter(1), nbdkit-file-plugin(1).
Richard W.M. Jones
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