Q

When is the right time to switch from tape to disk-based backup?

Before moving from tape to disk-based backups, you need to consider recovery objectives, the age of your current tape investment, backup and restore performance, and data protection.

When is the right time to switch from tape to disk-based backup?
While the price of disk decreases daily, the cost of tape does not. So for many organisations, the switch from tape to disk-based backup is on the agenda. However, businesses need to consider the bigger picture before making the switch, because the correct time to move is dependent on numerous organisational drivers, including:

  • Required recovery objectives
  • Age of the current tape investment
  • Amount of backup data
  • Data centre space
  • Backup and restore performance
  • Regulatory drivers
  • Existing backup technologies for data protection

While disk offers many benefits over tape, particularly around recovery performance, availability and data deduplication, organisations with large quantities of backup data will still struggle to produce financial justifications for entirely ditching tape. Most will have significant investments in tape and long-term backups retained on them. These inform two key questions to ask when moving off tape:

  • Do you want disk to replace tape entirely or use it to just complement tape?
  • What do you do with long-term data, as one day you still might need it?

If organisations are going to use disk to stage backups, they need to decide if this is for all backup data or just a subset. Also, they must determine if the subset is based on criticality, size, backup and restore performance, or data type? A common practice is to use disk to hold all but the largest backups for a period in which restores occur and then stage off. This introduces the benefits of disk into an organisation's backup service while retaining tape for the longer term, larger footprint and those tape-loving, large sequential backups.

If organisations plan to replace tape entirely, then they need to consider all the backup data they currently have on tape. Do you need all the data or only some, and how long do you need to keep it? While some technologies allow you to migrate from tape to disk, this may significantly increase your disk footprint and its cost. Thus, it is important to remember legacy data and historical restore requirements when planning for your disk-based strategy moving forward.

Additionally, disk will add complexity to your offsite backups. Because you will no longer be able to ship a piece of media to a second site, you will need to consider how you will protect that data. If you have a second location that meets all of your business and regulatory requirements, you can replicate between multiple devices at these locations or choose to repurpose your tape investment to create an offsite disaster recovery (DR) copy.

So while the financials aspects of disk-based backups are increasingly appealing, it is vital to consider all business drivers to ensure this adoption is successful.

This was last published in August 2009

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