Tape Backup is Dead! Long Live Backup-to-Disk! Posted By Greg Riedesel on August 3, 2011
Disk backups are a lot more convenient than tape, since restoring all kinds of data can be completed much faster. What’s more, all of the latest deduplication technologies can be used with backup-to-disk, so you’re not storing 5, 10, 20, 100 copies of the same data in your backup rotation. Some may say that disk is clearly the way of the future.
If only that were true. There is one area where tape is still quite competitive with disk, and that’s in truly long-term storage—as in, ten years’ worth of long term. Information retention policies can be quite conservative these days, so needing to keep ten-year-old data is not uncommon. And tape does have some advantages over disk:
- It doesn’t need power in order to keep it around.
- IIt doesn’t need hardware upgrades every 3 to 5 years.
- IThe price per gigabyte is a lot lower than disk.
- IIt’s shelf stable over decade time-scales.
- IIt allows certain specialized use cases, such as write-once media in very large sizes.
- IIf you have to keep data around for ten years, tape looks really attractive.
That said, the way tape is used in backup rotations has changed in recent years. More and more the daily backup duties are done by disk systems, and are then cascaded to tape for long-term archive. The modern tape drives are fast enough that the only way to keep them running at full speed is by spooling multiple, parallel backup sets out of the backup-to-disk system. Restores, when they happen, are similarly fast.
How does this impact discovery, though?
In olden days, discovery could produce actual tapes full of data to be sorted through. Frequently, these were tapes copied directly from the backup rotation. More recently, these were tapes containing the already-extracted contents of a discovery request, but put on tape for ease of transport. These days, such things get shipped on actual hard drives, if not transferred over the Internet directly.
The modern backup systems with large disk systems backed by huge deduplication logic can’t produce an equivalent to the backup tape of yore. The effort of creating such is very close to the effort needed to just extract the key bits of data being discovered, and if you’re doing that, you may as well copy it to a 2TB disk and overnight it (tape would be used for spite in this case). Even if a tape is created, it’ll be on a newer tape format where extraction should be relatively straightforward.
Is eDiscovery done with tape? Not really, but it will be a lot less common. When working with discoverable data going back ten years, lazy entities may just pull the tape out of archive and pass it over rather than go through the effort of pulling out just the right information. Or worse, they produce the tape because they themselves can’t use the tape and hope the discovery process can make sense of it.
But while we definitely will see a lot less of it from here on out, we’re not done with tape yet.
Originally published on Discovery Brain.
Post A Comment
Commenting is not available in this weblog entry.