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|Snapshot: Cheers and jeers for tiered storage").
Rudolph Technologies' Fitch regularly performs data migrations between multiple tiers of storage (see "Old data isn't the only candidate for tiering," below). "We have two different tiers of storage: Fibre Channel and Serial ATA drives," says Fitch. "The Compellent Data Progression Module that's part of Storage Center lets us automatically move data between Tier 1 and Tier 3 storage nondisruptively."
Fitch just sets a threshold for the number of days of nonuse for data. "Image files that aren't refreshed frequently are moved down to Tier 3 storage automatically. Only frequently accessed files stay up on our large, expensive Fibre Channel drives," he notes.
Data migrations are a fact of life and automating the tedious process can be well worth the effort. Users have found that host-based software is perhaps the best for application-specific migrations such as database replication. It frees the storage array of processing and can often be used more easily for migrating data between heterogeneous storage.
Array-based migration, such as that used by Compellent Technologies' customers, has also proven to be popular, and legions of customers use EMC's Symmetrix Remote Data Facility to move data between EMC arrays. Many users also rely on their chosen array's data utilities to migrate data from one array to another or to move data between tiers. Array-based migration from one array to another is a popular option not only for technology refreshes, but for heterogeneous storage migration. Finally, the use of a network appliance provides additional flexibility for moving file-, block- or volume-based data among heterogeneous devices.
This was first published in June 2008