...¹

A replica stores multiple backpointers when the file is hard-linked. A backpointer need not remember the locations of the parent-directory replicas, since a parent directory is always found on the same node due to the namespace-containment property (Section 4.3).

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...saito2002-prot.²

Due to the lack of wide-area file system traces, we analyzed the storage overhead using a fresh file system with RedHat 7.3 installed. The overhead mainly depends on the spatial locality of accesses, i.e., the degree to which files in the same directory are accessed together. We expect the overhead in practice to be much closer to 1.5% than 25%, because spatial locality in typical file-system traces is usually high.

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... replica³

The gold-replica set is kept as a part of the replica's attributes; see Figure 3.

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...⁴

Pangaea batches NFS write requests and flushes data to disk and other replicas only after a ``commit'' request [4]. Thus, the size of an update can grow larger than the typical ``write'' request size of 8KB.

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...⁵

The replica can always find a replica of the parent directory in the same node, because of the name-space-containment property.

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... benchmark⁶

This benchmark is available from https://www.hpl.hp.com/personal/ysaito.

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... sessions⁷

We define a session to be either a directory operation (i.e., unlink), or a series of system calls to a file between and including open and close. If any one of the system calls fails, we consider the session to fail.

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