Hi Daegyu,
On 09/08/2019 09:10, 한대규 wrote:
Hi, I'm Daegyu from Sungkyunkwan University.
I'm curious how GFS2's filesystem metadata is shared between nodes.
The key thing to know about gfs2 is that it is a shared storage
filesystem where each node mounts the same storage device. It is
different from a distributed filesystem where each node has storage
devices that only it accesses.
In detail, I wonder how the metadata in the memory of the node mounting GFS2
looks the consistent filesystem to other nodes.
gfs2 uses dlm for locking of filesystem metadata among the nodes. The
transfer of locks between nodes allows gfs2 to decide when its in-memory
caches are invalid and require re-reading from the storage.
In addition, what role does corosync play in gfs2?
gfs2 doesn't communicate with corosync directly but it operates on top
of a high-availability cluster. corosync provides synchronization and
coherency for the cluster. If a node stops responding, corosync will
notice and trigger actions (fencing) to make sure that node is put back
into a safe and consistent state. This is important in gfs2 to prevent
"misbehaving" nodes from corrupting the filesystem.
Hope this helps.
Cheers,
Andy
