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Vol. 1 No. 4 June 2002

Snapshots save time and data

In the world of global business, the demand for information never sleeps. With continuous availability requirements, snapshot techniques that provide an instant data copy help speed up routine maintenance procedures to backup, archive and protect data. Snapshots are also useful in development environments, for content distribution and other information repurposing needs, saving time and resources that are already stretched too thin. A snapshot is an image or copy of a defined collection of data created instantly at a point-in-time. Copies are made almost immediately within the disk subsystem, despite the size of the volume. Taking a copy-on-write snapshot 1. Disk subsystem stores on a base volume before snapshot. 2. Subsystem creates snapshot volume, which has a pointer to data at that point in time and an empty index. 3. Subsystem updates base volume by writing to new blocks, but points to original blocks in snapshot index. Those blocks will not be overwritten by base volume. Contrast the snapshot with a traditional full-volume...

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Features in this issue

  • Now, That's a Cluster!

    Lawrence Livermore National Labs is pushing the envelope with a new storage cluster that mates 115TB of networked disk with a massive cluster of 600 dual Pentium 4 servers.

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