I CC'ed the original to you because rsync.net has a 500GB minimum size for an account at a very modest price, and could also be used to backup other standards artifacts.  For example, I could natively backup all the SRFI GitHub repositories since rsync.net has direct git support.  And the mailing list archives, and whatever else that's important. I'm assuming another offsite backup system where ownership and access can be shared would help to avoid a loss of data like the one that occurred for R6RS.  I follow the standard backup rule of thumb that "if you have 1, you have 0, if you have 2, you have 1...", and rsync.net has proven itself to be very solid in the 10 years I've used it, allowing me to recover from a disaster where 2 our of the 3 copies of some important data were lost.