The requirement for 2 drives is not mandatory, it ought to be just a suggestion. LTO can be used as a standalone drive, TSM can use single drive or small autoloader with single drive. So it is NOT required but recommended. For business reasons it may be necessary to have 2 or even more drives. Others already pointed reclamation and off-site copying problems you may have. They can be worked around but again you have to compare performance and total costs - single drive reclamation - define reclamation storage pool of type FILE. On reclamation remaining data is moved to files and later written to new tape volume. Drawback: data is not read when written (sequential read+write vs. parallel) thus takes more time. Calculate time budget around the clock. - single drive copypools - define following hierarchy DISK -> FILE -> LTO (file pool would be also lto reclamation pool). Prevent file->lto migration during backups (highmig=100). Perform backups to copypool after node backups finish. Allow migration after backup to copypool finishes. Drawbacks: filepool must be large enough to hold all backups data. Backups should not happen during migration because some object(s) may migrate without being copied to the copypool. Again time - data have to be written twice through the one-and-only drive. And on the end with one drive there is no way to perform copypool reclamation. Conclusion: for a small installation data might be not too much, time might be enough for all activities (node backups, copypool backup, primary pool raclamation, migration, DB backup). Thus neither LTO technology nor TSM dictate number of drives to be used but only the business requirements you have.
Zlatko Krastev IT Consultant Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] cc: Subject: 2 drives are required for LTO? One of the System Admins has been talking to an IBM Business partner and was told, apparently, that the use of two drives is not only recommended but is also required with LTO. Is this true? If so, why? I checked out http://www.tivoli.com/support/storage_mgr/devices/lto.html#notes and noticed that some LTO libraries are noted A/E meaning that Advanced Managed Library feature" is required? Is there a technical reason for this? ______________________________________________________________________ Post your ad for free now! http://personals.yahoo.ca
