K. McCoy. VMS File System Internals. Digital Press, 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....costs, conventional versioning implementations still involve one or more new metadata blocks per version. On average, the metadata versions require as much space as the versioned data, halving the achievable detection window. Even with less comprehensive versioning, such as Elephant [37] or VMS [29], the metadata history can become almost ( 80 ) as large as the data history. This paper describes and evaluates two methods of storing metadata versions more compactly: journal based metadata and multiversion b trees. Journal based metadata encodes each version of a file s metadata in a ....

....from user mistakes, recovery from system corruption, and analysis of historical changes. Each category stresses different features of the versioning system beneath it. Recovery from user mistakes: Human users make mistakes, such as deleting or erroneously modifying files. Versioning can help [17, 29, 37]. Recovery from such mistakes usually starts with some a priori knowledge about the nature of the mistake. Often, the exact file that should be recovered is known. Additionally, there are only certain versions that are of any value to the user; intermediate versions that contain incomplete data ....

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K. McCoy. VMS file system internals. Digital Press, 1990.

....from user mistakes, recovery from system corruption, and analysis of historical changes. Each category stresses different features of the versioning system beneath it. Recovery from user mistakes: Human users make mistakes, such as deleting or erroneously modifying files. Versioning can help [16, 28, 37]. Recovery from such mistakes usually starts with some a priori knowledge about the nature of the mistake. Often, the exact file that should be recovered is known. Additionally, there are only certain versions that are of any value to the user; intermediate versions that contain incomplete data ....

....that would be available in a comprehensive versioning system. 2.2.1 Common heuristics A common pruning technique in versioning file systems is to keep only the last version of a file from each session; that is, each CLOSE of a file creates a distinct version. For example, the VMS file system [28] retains a fixed number of versions for each file. VMS s pruning heuristic creates a version after each CLOSE of a file, and if the file already has the maximum number of versions, removes the oldest version of the file when this new version is created. The more recent Elephant file system [37] ....

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K. McCoy. VMS file system internals. Digital Press, 1990.

....Secondly while the cache manager is expensive when all caches are warm, its impact on performance appears to be much smaller than that of having to take data off the disk or over the network. In the context of a non persistent cache, this protocol has already been explored before by VaxClusters [12] Sprite [8] Spritely NFS [7] and SMB [6] In AFS 3 [2] and DFS DCE the entire cache manager was moved into the kernel, so one may expect that these systems to have good performance. However, experiments cannot confirm this. A warm cache comparison of the ls lR test on NetBSD s FFS and AFS running ....

Kirby McCoy, Vms File System Internals, Digital Press, 1990.

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K. McCoy. VMS File System Internals. Digital Press, 1990.

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K. McCoy. VMS File System Internals. Digital Press, 1990.

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K. McCoy, VMS File System Internals, Digital Press, 1990.

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Kirby McCoy. VMS File Systems Internals. Digital Press.

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K. McCoy. VMS File System Internals. Digital Press, 1990.

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