Paul Kruschwitz’s Blog

If you are going to run your VTL near it’s capacity, you need to understand how to insure that you are not retaining data that your backup application has already expired.

An advantage virtual tape has over physical tape is that the storage for a virtual tape can be assigned to other virtual tapes when not in use.  This Capacity On Demand (COD) assignment provides better storage utilization and performance by spreading the I/O throughout the storage system.  The problem with this scenario is that the backup software does not tell the VTL when the virtual tape is no longer needed, so the data on the virtual tape stays until the virtual tape is re-written.

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It is hard for a technical person to not ask how something works.  How does one deduplication technology differ from another?  How big of a block size does it use?  What form of hashing is it using?  These are all great technical questions, but what are the really important questions?

1. Does it meet my requirements?

2. How much will it cost?

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