1.7. 全​​​​​​​球​​​​​​​网​​​​​​​络​​​​​​​块​​​​​​​设​​​​​​​备​​​​​​​

全​​​​​​​球​​​​​​​网​​​​​​​络​​​​​​​块​​​​​​​设​​​​​​​备​​​​​​​（Global Network Block Device，GNBD）提​​​​​​​供​​​​​​​通​​​​​​​过​​​​​​​ TCP/IP 访​​​​​​​问​​​​​​​ Red Hat GFS 块​​​​​​​设​​​​​​​备​​​​​​​的​​​​​​​功​​​​​​​能​​​​​​​。​​​​​​​GNBD 从​​​​​​​概​​​​​​​念​​​​​​​上​​​​​​​和​​​​​​​ NBD 相​​​​​​​似​​​​​​​；然​​​​​​​而​​​​​​​，GNBD 是​​​​​​​和​​​​​​​ GFS 相​​​​​​​关​​​​​​​的​​​​​​​且​​​​​​​为​​​​​​​ GFS 单​​​​​​​独​​​​​​​进​​​​​​​行​​​​​​​了​​​​​​​调​​​​​​​整​​​​​​​。​​​​​​​当​​​​​​​需​​​​​​​要​​​​​​​更​​​​​​​健​​​​​​​壮​​​​​​​的​​​​​​​技​​​​​​​术​​​​​​​时​​​​​​​，GNBD 是​​​​​​​有​​​​​​​用​​​​​​​处​​​​​​​的​​​​​​​ — 光​​​​​​​纤​​​​​​​通​​​​​​​道​​​​​​​或​​​​​​​ single-initiator SCSI — 不​​​​​​​是​​​​​​​必​​​​​​​需​​​​​​​的​​​​​​​或​​​​​​​成​​​​​​​本​​​​​​​过​​​​​​​高​​​​​​​。​​​​​​​

GNBD consists of two major components: a GNBD client and a GNBD server. A GNBD client runs in a node with GFS and imports a block device exported by a GNBD server. A GNBD server runs in another node and exports block-level storage from its local storage (either directly attached storage or SAN storage). Refer to 图 1.18 “GNBD 概​​​​​​​述​​​​​​​”. Multiple GNBD clients can access a device exported by a GNBD server, thus making a GNBD suitable for use by a group of nodes running GFS.