4.1. Changes that cause TSM to resend data to the HFS

There are several sets of circumstances in which TSM can be inadvertently prompted to resend data unnecessarily. If you find that you have made changes of the sort listed below, then your TSM account may get locked because you sent more than the daily backup limit allows. To avoid this, stop your TSM scheduler and run manual backups, keeping within the daily limits until your backups complete again. For how to stop the TSM scheduler, please see our instructions for Windows, Mac, Linux. and Solaris. For how to keep within the daily limit and so avoid your account getting locked, see our FAQ item How can I limit the amount of data that I'm backing up?.

  • Renaming your machine - in Windows, TSM stores data by UNC path, which means that e.g. on a PC called my-laptop, C: would be represented as \\my-laptop\c$, D: as \\my-laptop\d$, and so on. Renaming a Windows machine changes that path, causing a complete resend of data under the new path - e.g. \\my-renamed-laptop\c$, \\my-renamed-laptop\d$. So please avoid renaming your machine unless absolutely necessary, and if you do have to then please e-mail us at hfs@ox.ac.uk. Please note that this is only true of Windows: renaming Mac and Linux machines causes no such problem.
  • Changing drive names or drive letters - similarly, changing a drive name will cause a resend of data from that drive. All data on a Mac external drive renamed from /Volumes/my-external-drive to /Volumes/my-renamed-external-drive would be resent by TSM. In Windows, take care not to vary the order in which you attach any extra drives - Windows will assign them different letters if you change the order, so you might find that TSM resends the data that you backed up from E: again from F:, as if F: were a different drive.
  • Moving, renaming, or changing permissions on data - this will generally also cause TSM to resend. If you have a folder called data and you rename it to e.g. old-data then TSM will regard it as new and resend the entire contents of that folder, including all sub-folders. Changes of permissions usually also occasion resends. We therefore request that large-scale changes to your data be avoided unless absolutely necessary.

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