I'm creating a simple backup system in place that creates incremental backups. I already have plans on storing the backups offsite, and they are also stored locally on the same system that creates them, on the same hard disk that the originals are on. I'm looking to improve the backup system further, by storing it on an alternate media locally.
The files that I'd like to backup are usually very small (>100Mb), but will be created at regular intervals (eg one a day). I already have a script that creates the file at regular intervals. The files will only ever be read in sequential order; reading individual files and knowing the filenames will never be required. I will never need to access a backup older than 90 days, so longevity is not really a consideration. The files have built in check summing, but it does not correct issues, only validates that the files have at least one fault.
While LTO would seem like the best option for this, I'd like to keep the short term costs extremely low. It would also be a benefit if the media in question is write-once. Because of this I believe using DVD-R's could be the best option.
DVD's don't come without some concerns however. I would not like to wait until I have enough data to fill one DVD, nor would I like to use one DVD per backup period. The computer has 2 DVD drives, so ideally I would put a DVD into both of them, and program my script to alternate between them, ejecting them once full. As the files are able to be read sequentially, I don't really need a filesystem, but I will need a way of preventing reading unburned garbage data, and knowing when the disk is full/how much is left. I'll also need to do this all with commands for automation.
Is there a way to write to a DVD across multiple days, essentially treating it like a tape?
