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Re: [Linux-cluster] strange slowness of ls with 1 newly created file on gfs 1 or 2



Pavel Stano wrote:

and then run touch on node 1:
serpico# touch /d/0/test

and ls on node 2:
dinorscio:~# time ls /d/0/
test


What have you expected from a cluster filesystem ? When you touch a file on node 1, it is a "create" that requires at least 2 exclusive locks (directory lock and the file lock itself, among many other things). On a local filesystem such as ext3, disk activities are delayed due to filesystem cache where "touch" writes the data into cache and "ls" reads it from cache on the very same node - all memory operations. On cluster filesystem, when you do an "ls" on node 2, node 2 needs to ask node 1 to release the locks (few ping-pong messages between two nodes and lock managers via network), the contents inside node 1's cache need to get synced to the shared storage. After node 2 gets the locks, it has to read contents from the disk.

I hope the above explanation is clear.

and last thing, i try gfs2, but same result


-- Wendy


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