Tuesday, March 06, 2007

Use of CDSL (Context Dependent SymLink) in OpenSSI

CDSL (Context Dependent SymLink) feature in OpenSSI can be quite useful.

First of all, what is it?
Normally, when you create a file or dir on a OpenSSI cluster, there will be only one copy/image/piece (or whatever you want to call it). That means node 1, node 2, or node N all access the same file when a process running top of that particular node tries to make a file I/O.

There are times when you want to make this file I/O independent of the cluster. For example, if you want "onnode 1 vi /testdir/hello.txt" and "onnode 2 vi /testdir/hello.txt" to load different /testdir/hello.txt file (that is, depending on which node the vi process is running on), how would you do that?

The answer is to use CDSL. It's quite simple. Simply type
"mklocalfile /testdir/hello.txt" will turn the file into a CDSL.
"mkglobalfile /testdir/hello.txt" will turn it back into a normal file.

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