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TechNote:
Hierarchical Storage Management
Hierarchical Storage Management (HSM) is becoming increasingly important for maximizing the return on enterprise investments in storage resources. HSM can be a part of, but not the total answer to Information Lifetime Management (ILM). Often, high-performance storage is being used to store data that is for reference only, or for data that is older and thus now infrequently used.
By implementing an automated system and policies for migration of such data to less expensive disk storage, or to tape, the useful life of existing storage capacity resources can be indefinitely extended. An HSM system permits automated and transparent recovery of data from tape or secondary disk storage upon demand, while retaining the protected tape copy or copies locally or off-site.
Secondary disk storage can be composed of FC-connected ATA or Serial ATA RAID drive arrays. Architectures for replicating data to remotely sited tape are possible.
SAN-Aware HSM
Integration of HSM capabilities in a SAN architecture offers many advantages, but the HSM software must be SAN-aware. ADIC's StorNext Management Suite allows a mixed OS environment to share common access to a single set of files, and provides the best integration of HSM and SAN capabilities today (http://www2.adic.com/stornext/).
larger imageStorNext supports a wide variety of OS's including Windows, Solaris, Linux, and AIX. An ADIC case study is available on the ADIC website (http://www.adic.com/us/collateral/CS_AFRL.pdf). It describes InfraStor's installation of StorNext in a 40TB SAN environment along with an ADIC Scalar 10K, 250TB tape library. ADIC’s latest iPlatform i500 and i2000 libraries provide integrated FC connectivity with “pay-as-you-grow” capacity scalability from a department-level 34 cartridges to an enterprise-capable 3,492 tape cartridges.
Conventional IP-based HSM
CaminoSoft's (www.caminosoft.com) Managed Server HSM is an example of a more traditional HSM implementation that allows easy scalability for implementing HSM on just one server, or many. The CaminoSoft Managed Server HSM is loaded on a client application server and through a set of user-managed policies migrates files to a central server resource. The secondary server can be a NAS device, SAN-attached storage, or a second CaminoSoft IP-connected device that manages a connection to a tape library. CaminoSoft uses the Computer Associates media management library, so that a wide range of devices can be supported.
Managed Server HSM is available for Windows and Netware, and in fact CaminoSoft's product provides the only HSM solution for Netware today. InfraStor is a CaminoSoft partner.
HSM and Email Archiving
HSM can also be part of an Email Archiving system; however, software that combines Indexing and Archival capabilities with HSM needs to be application-aware. For example, Symatec's Enterprise Vault incorporates a policy-driven HSM capability to migrate mail-server objects (Exchange and Lotus-Notes) off of the mail server, leaving behind a "stub" pointer. The pointer allows subsequent return of the migrated object to the mail server in an automated fashion from secondary storage. Separately, Enterprise Vault offers Journaling functions that are critical to maintaining Regulatory Compliance.
HSM and File Indexing/Search Capabilities
An important adjunct to HSM as applied to data on a file server is the ability to index files for later retrieval, even after they have been migrated to secondary storage. As for HSM/Archival of Email, the HSM application needs to be application and file-type aware. For example, a spreadsheet, PDF, or word-processing document may each qualify for migration from primary to secondary storage. By indexing the files as part of the migration process, not only is the data automatically recoverable via the "stub" pointer, it is also recoverable as part of an arbitrary search of metadata created by the full-text indexing process. This capability is offered by the Symantec Enterprise Vault software, and is an important part of the vision for ILM as well as a significant enabler of Regulatory Compliance.
HSM and Backup
While HSM utilities typically maintain more than one copy of the original data, manufacturers are careful to emphasize that HSM is not a replacement for regular backup, and HSM systems are not designed to facilitate complete recovery of a server's data. What is true, is that the reduction in the size of the data store on the source volume contributes to very much faster backups. Regular backups of the source volumes with the pointers, and the migrated data are essential. Typically HSM systems hold migrated data in logical container volumes and require the pointers to be able to locate individual files. Lower frequency incremental backups of the migrated data can be scheduled following scheduled migration tasks.
HSM and Continuous Data Protection
There are many similarities between Continuous Data Protection (CDP) methods and the combined journaling and archiving systems that are coupled with HSM; however at the current time they are still separate functions. It is to be expected that greater overlap of these functions will develop in the future.
InfraStor Technologies can provide the proper selection of capabilities for implementing an HSM system, whether it is for a few servers with Direct-Attached Storage or many devices on a SAN with requirements for shared access or indexed archival for Regulatory Compliance.
Key Point Summary
HSM:
- Part of ILM strategies
- Can be implemented on SAN’s or on NAS
- On SAN’s HSM solution must be “SAN-aware”
- Can be combined with Email or file-level Indexing and Archiving
SAN-based Multi-Platform HSM:
- ADIC’s StorNext Management Suite supports a wide range of OS’s, and is SAN-aware
- Uses a SAN file system to enable shared access to SAN storage
- HSM functions run on Solaris and Linux servers
IP-based HSM:
- CaminoSoft’s Managed Server HSM allows scalability from one to many servers
- Only solution for Netware
- Supports Windows
HSM and Regulatory Compliance
- Symantec’s Enterprise Vault offers HSM capabilities combined with Indexing and Archiving of files and emails for Regulatory Compliance