Tape has been the chosen form of backup media for decades, but with newer technologies, this is changing. Now other contenders are creeping up on this venerable format. What is the current sweet spot in backup media types for 2009? Is it:
- Hard Drives
or something else? The basis of this recommendation is done with the following criteria:
- The media should ideally be able to hold a single full backup of the data you're working on, although...
- You can have up to 2 media for each backup cycle.
- The current working size of the data set is less than 1 terabyte. Total on-line storage capacity is less than 3 terabytes.
- Data compression is enabled for the backup process.
- The backup media will be part of a rotating set, which means the media will see re-use at some point in the year.
- The rotation cycle is fairly short, less than 30 days.
- Media is taken daily off-site. Yearly backups are taken off-site permanently.
- The backup process has approx. a 4-6 hour window to complete, although it can run over if needed.
For the record, my work currently uses tray-loaded hot-swap eSATA enclosures for 500Gb hard drives, although I see that people are still using tape, which is what lead to this question.
This is a follow-up to Evan's questions:
- What's the offsite rotation schedule (weekly, daily, multiple times / day, etc)?
As above the prior night's backup is taken off-site, and returned the next morning. At the end of each fiscal calendar, a complete backup is taken and shipped to off-site storage.
- Do you have any idea of the size of a hypothetical daily incremental backup (ie. size of the daily working set - you say "working size", but I believe you're referring to the entire backup corpus)?
Correct, the corpus is less than 1 Tb. Daily changes constitute about 200Gb.
- You say "You can have up to 2-3 media for each backup cycle"-- I'm taking that to mean that a "full backup" should use 2-3 media, not that you want to have 2-3 sets for each "generation" (grandfather, father, son, etc).
Also correct, the target is 1 "media unit" per backup cycle, although in some cases it can be extended to two.