Group: Forum Members
If you're using Incrementals Forever and you only have a single Full, then the free space threshold purge option can't be used. If your Incrementals are typically only 1-10 GB in size, I can't imagine how you had a problem creating a new one if you have 650 GB free. Was this new Incremental really going to be 65-650x larger than your average Incremental? Can you post the log from the job that failed? (Just make sure NOT to include your Reflect license key that is included at the bottom of each log.)
On a side note, are you either using a destination disk rotation or at least replicating these backups anywhere else? If not, you have a pretty high-risk backup strategy. First you have the general risk of only having a single backup set (i.e. only one Full backup), which means that if your Full ever becomes corrupted or partially unreadable due to an issue on your destination disk, then all of your backups are rendered useless. That's why I typically only recommend Incrementals Forever with Synthetic Fulls to people who are using a disk rotation so they have multiple backup sets in total even if each disk only has one set, or else are at least replicating backups somewhere. Either of those strategies also protects you from losing of your backups due to a failure of your disk, which is a nice additional benefit regardless of your backup strategy.
And then secondly, 60 Incrementals is a pretty long chain. There's nothing technically wrong with that when everything is working well, but it means that restoring Incremental #60 requires that all 59 previous Incrementals and the parent Full all be intact. The longer the dependency chain, the greater the risk.
If you don't plan on using a disk rotation or replication, then I would strongly recommend that you adjust your strategy so that you can store at least 2 Full backups, perhaps by creating a new Full each month. Of course if your Fulls are 2TB, then a 4TB disk isn't enough to store those plus 60 Incrementals. Another option you could consider would be something along the lines of monthly Fulls, weekly Diffs, and daily Incs. That would give you two benefits. First, your Incremental chains will become much shorter due to the weekly Diffs. And second, you would have the option of "thinning out" your backups. Right now since you're only using Fulls and Incs, if you want to retain 60 days' worth of history, you need to retain all 60 Incrementals. But if you set your retention policy to 8 Diffs and maybe 14 Incrementals, you could have daily backups going back for 2 weeks, and weekly backups going back 2 months. So you'd still be able to reach back farther in time, even if you won't have daily backups available that far back. But do you actually need individual DAILY backups going back that far? If not, then you wouldn't have to retain your daily Incrementals for as long.
Just some food for thought. But again, even if it became clear what caused your error, I think it would be worth considering a larger drive in order to implement a safer backup strategy.