ceph/doc/cephfs/lazyio.rst

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LazyIO
======
LazyIO relaxes POSIX semantics. Buffered reads/writes are allowed even when a
file is opened by multiple applications on multiple clients. Applications are
responsible for managing cache coherency themselves.
Libcephfs supports LazyIO since nautilus release.
Enable LazyIO
=============
LazyIO can be enabled by following ways.
- ``client_force_lazyio`` option enables LAZY_IO globally for libcephfs and
ceph-fuse mount.
- ``ceph_lazyio(...)`` and ``ceph_ll_lazyio(...)`` enable LAZY_IO for file handle
in libcephfs.
- ``ioctl(fd, CEPH_IOC_LAZYIO, 1UL)`` enables LAZY_IO for file handle in
ceph-fuse mount.