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HSM in today's environment
So, is there a place for HSM? The answer is a qualified yes. Some reasons to consider HSM today are:
- To reduce costs of storage management
- To improve backup/restore performance
- To improve management of large e-mail repositories and other databases
|When disk wasn't cheap|
HSM also dramatically improves backup operations. In traditional backup environments, full backups are performed on a regularly. Studies have shown that a large percentage of files on file servers are rarely accessed after a few months, yet these files continue to impact the time required to perform backups and the amount of media consumed.
With HSM, these files would be migrated to tape with stubs--or fingerprints--left on primary storage, greatly reducing the size of the primary data stores. They would no longer be constantly backed up, thereby improving backup and recovery times and reducing tape consumption.
Similarly, a problem plaguing many environments today is the growth of e-mail and databases. Several vendors offer HSM-related products specifically designed for use with applications such as Microsoft Exchange or Oracle that enable the migration of old messages, attachments and infrequently accessed records to other media (see "Application-focused HSM/HSM-related products"). The promised result is a reduction in the size of the primary repositories.
Integrating an HSM solution into a storage management framework shouldn't be approached without evaluating the impact on the rest of the organization. You should consider four main questions:
How well do you know your data? There needs to be a solid understanding of the data being managed in order to establish appropriate policies that correctly align with the value of the data at risk. Simply determining that a file hasn't been accessed for a certain period of time isn't sufficient to make it a candidate for migration. A clearly defined data classification methodology with broad support within the organization is one requirement for a successful HSM implementation.
What's the impact on users and applications? The impact of delays in accessing data needs to be understood before deploying HSM. Are delays acceptable? Can they be mitigated with near-line storage? Can your applications handle them appropriately?
How does HSM impact backup and other storage operations? It's important to understand what operational changes will be required to accommodate HSM. Also, where will HSM software or agents need to be deployed, and what's the impact?
How can I back out the HSM solution from the environment, if necessary? If HSM turns out to not be the right solution or there's a desire to change vendors, it's important to understand the level of effort and impact to return the environment to its non-HSM state.
With the evolution of storage networks, low-cost disk, and enhanced software offerings, HSM is worth another look. Application-focused HSM solutions, in particular, have the potential to provide some unique benefits. The success of these solutions depends on a clear understanding of requirements, benefits and risks.
This was first published in May 2003