IT Services



Best practice for use of TSM and the HFS


Contents



1. Introduction

The following recommendations give advice on how to get the best use of TSM and the HFS backup service.



2. Limit what you back up



2.1. Only back up what you need to back up

The fewer files that you select for backup, the quicker your backup will be, and the less you will use the university resources involved in sending your data to the HFS and in keeping it stored there. You are also more likely to notice any problems with your backups (such as files failing to be backed up) if you keep your backups to a manageable size.

  • If you are only running manual backups, please see our instructions on how to select only certain files for backup in our instructions on running a manual backup in Windows, Mac and Linux.
  • Use TSM exclude rules to exclude from backup anything that you do not need or do not want to send: this will prevent such data being sent to the HFS accidentally. If you leave your machine switched on and it runs a scheduled backup, TSM will back up all the data that it can from any drives that are attached to your machine, as well as your main drive. So, if necessary, exclude from backup any drives that you do not want to back up, e.g. ones that duplicate data that is on your main drive, using our instructions for excluding drives and partitions from backup. Then exclude any other data that you do not wish to back up, which might include temporary files and non-work related data, by using our instructions for excluding files and folders; or if you have only a limited data set to back up then exclude everything from backup except specific files or folders.


2.2. Only back up your work

The HFS is intended for the backup of your university-related work. So, whilst we understand that hard drives may contain a combination of both work and personal data, please try to exclude from backup your non-work files, using the instructions mentioned in the previous section. This is particularly important in the case of copyrighted material such as music and movies, which can take up a substantial amount of hard drive space. We already exclude certain files from backup, most notably temporary files and virtual machines - on this please see further our page on files and folders excluded from backup.



3. Check that your backups are working

For all accounts except those registered for manual backup only, e-mails are sent out if a scheduled backup fails to run correctly. However these mails are only a guide, and the absence of TSM scheduled backup failure report does not guarantee that every single file has been backed up. We therefore recommend that you verify that your backups are running as intended.



4. Avoid making large-scale changes to your computer or your data

Sometimes making large-scale changes to your computer is unavoidable. Please bear in mind, though, that such changes may affect your backups. The lists below cover the most common types.



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.


4.2. Other changes

There are other changes that are system-wide but which generally do not cause a resend of your data, but which can have other unforeseen consequences - these are listed below.

  • Changing operating system by upgrading an existing machine - if you intend to upgrade an existing machine then please go to our page on downloading the TSM software for the IT Services HFS backup service to upgrade TSM to the correct version for your new operating system.
    • If your new operating system is not listed on that page, we would recommend that you delay upgrading, if possible, until a supported version of TSM is released. TSM accounts seen to be using an unsupported operating system will be locked, and their contents preserved, until the relevant TSM version is available. Please note that we do not support beta or release candidate operating systems.
    • If your new operating system is listed, please upgrade TSM immediately after you have upgraded your operating system. This is because new versions of TSM do not support older operating systems, so if you upgrade from (say) Windows Vista to 7, or from Mac OS X Snow Leopard to Lion, then you may find that your existing version of TSM is no longer supported to work on your machine. Though TSM may appear to run, results of such backups are unpredictable, and it is important to upgrade. There is no need to uninstall the old version of TSM before installing the new one.
  • Changing operating system by moving to a new machine - if you are moving between similar operating systems, for example replacing a machine running Windows Vista with one running Windows 7, then you may keep your existing TSM nodename. But if you are changing platform - moving between Windows, Mac and Linux - then please register a new TSM node. This is because TSM does not support cross-platform restores, so you cannot swap between Windows, Mac and Linux. If you do, you may corrupt your account and so render your data inaccessible.
  • Moving your computer's location - DNS/IP address changes are not important, that is to say, moving your machine and backing up from a different location will not cause any problems; nor will it cause data to be resent.


5. Keep data sets to a manageable size

TSM works on each data partition/drive as a whole. It composes a list of what is on your machine, compares that with what is stored on the HFS, and backs up the difference. If, therefore, you have many millions of files in one partition, TSM can become very slow as it tries to process the whole list at once. Before you first back up, please first of all consider the arrangement of your data and split it into partitions - ideally of no more than 1TB and a few million files in each.



6. Cease backing up from drives whose data is needed for restores

If data is lost from your machine and you then run a further backup, then the copies of those files on the HFS are scheduled for deletion, and only kept for up to 90 days. So if you lose data from (for example) a Windows drive C: and then back up C:, the HFS copies of your data are at risk. We therefore recommend that as soon as you discover you have lost data from an existing machine, you stop your TSM scheduler. For how to do this, please see our instructions for Windows, Mac, Linux. and Solaris. Alternatively, please email us at hfs@ox.ac.uk and ask for your data set to be renamed, so that you do not accidentally back up over it.



7. Register one account per operating system

You can register as many TSM accounts as you need in order to back up your data. For most people this will mean one TSM nodename per physical machine, though in the case of a multi-boot machine a TSM nodename is needed for each operating system that you wish to back up. So, for example, if you manage a lab of machines all running just Windows, then you may register each one; or if you have a dual-boot machine running Windows and Linux then you should register for two TSM accounts, if you wish to back up both operating systems. However:



8. Let us know if you stop using the HFS

In order to manage our system efficiently, the HFS Team will remove any backup account, including its data, that has not backed up for 90 days or more; and, similarly, any individual partitions which are in an active account but which have not been backed up for 90 days or more will be deleted. Before doing so, we attempt to inform the registered contact with up to three warning mails. This process is described in our page on deleting old backups.



8.1. If you go away temporarily

We can keep your data for you while you are away, if you are leaving Oxford temporarily and cannot back up regularly - for example because you are on extended leave away and your machine is in Oxford. Contact hfs@ox.ac.uk to ask us to retain your backups, letting us know when you will be away till. Please note that we can keep data from dormant accounts only for a reasonable period of time.



8.2. If you leave Oxford University

If you have finished with your TSM account, please uninstall TSM and deregister your TSM account. This saves resources at the HFS end, as otherwise we retain unused accounts for up to 90 days before deletion.