As certain Hierarchical Storage Management (HSM) systems do not scale as well as others, users frequently need to migrate to more capacious solutions in order to meet their storage needs. In his blog post, Israel Pacheco The Challenge - Migrate HSM Systems offers some suggestions for migrating large volumes of data from old to new HSM systems in a timely fashion.

Some of the frequently used methods are:

1. Migrate by user access

This method requires parallel operation of the old and the new system and leads to frequent tape mounts of the same tapes, Pacheco notes. Because files that have not been accessed would not migrate without additional effort, this process is very time consuming and can take years or forever because progress depends on user access.

2. Copy the files over to the new system

This method is usually much faster than method 1, but parallel operation of both HSM systems is still necessary, Pacheco writes. When the files are simply copied from the old to the new system, they are usually not sorted by tape and position. This results in slow restore speeds due to massive amounts of tape mounts and lots of tape positioning.

3. Use a data access system (SRB type)

Even if the drivers for the HSM systems in use are available, parallel operation until all data is migrated is necessary.

Pacheco writes that all three methods require parallel operation of the old and the new HSM system and, therefore, the old system has to stay in full operation until the migration is finished, which can take many month or even years in large environments. This is a significant cost factor and requires substantial spending on space, power, support, maintenance and administration.

In order to make a migration to SAM/QFS from Sun Microsystems easier, SAM/QFS provides a special API to facilitate migrations. This API provides the following capabilities, Pacheco points out:

• 1. Create the directory and file structure (inodes only) from the metadata of the old HSM system. This takes usually just a few hours and depends on the number of files in the old HSM system. As soon as the inode and directory structure is created, users and application have immediate access to the old data via the new SAM/QFS file system.

• 2. Access to the data from the old HSM's media by means of callouts, i.e. the data is brought over by request from SAM/QFS. The API does not provide the means to read the other HSM media directly, however. This has to be done by either using standard methods like accessing the other HSM via FTP or NFS or invoking special tools.

Pacheco cautions that, even with the APIs in use, it still requires parallel operation of the old HSM system and SAM/QFS. To get access to the data in the old HSM system the data must still be read in the old system, then use FTP or NFS to transfer them to SAM/QFS.

More Information

SAM-QFS: Tool for Cost Efficient, Reliable Long Term Storage [...read more...]

		fullsource
Print Email Current Profile Archive Blog Generate newsletter