Difference between revisions of "Why do I need a cluster file system"
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imported>ThorstenStaerk (New page: Why do you need a special file system if you have more than one computer accessing a partition? First, if two computers have file system cache, it can happen that one writes a block and t...) |
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First, if two computers have file system cache, it can happen that one writes a block and the other one fetches an obsolete block from its cache, so there would be inconsistencies. But if you switch off file system cache, this problem is solved. | First, if two computers have file system cache, it can happen that one writes a block and the other one fetches an obsolete block from its cache, so there would be inconsistencies. But if you switch off file system cache, this problem is solved. | ||
| + | |||
| + | OK, let's look at the next problem: Computer A reads a counter file and increases it: | ||
| + | Computer A reads 20 | ||
| + | Computer B reads 20 | ||
| + | Computer A writes 21 | ||
| + | Computer B writes 21 | ||
| + | And we have inconsistencies. But wait, this is not a cluster-specific problem, you will have the same problem in a multi-tasking environment. | ||
Revision as of 16:36, 2 April 2009
Why do you need a special file system if you have more than one computer accessing a partition?
First, if two computers have file system cache, it can happen that one writes a block and the other one fetches an obsolete block from its cache, so there would be inconsistencies. But if you switch off file system cache, this problem is solved.
OK, let's look at the next problem: Computer A reads a counter file and increases it:
Computer A reads 20 Computer B reads 20 Computer A writes 21 Computer B writes 21
And we have inconsistencies. But wait, this is not a cluster-specific problem, you will have the same problem in a multi-tasking environment.
