If you're willing to deal with the time it will take to write it all out, then its doable. You need a backup software that supports VTL (virtual tape library). With this, the physical drives are seen as tape devices. So it will start writing to drive #1 and when its full it will say "out of media" and it *should* pause for new media. You "eject" the drive, attach a fresh one, and hit continue. Then wash, rinse, repeat til complete. As others pointed out, it will take some time. You can speed it up with eSATA or USB 3. If you're on a Mac, you can speed it up using t-bolt. I believe Arkeia still offers a free version and they did/do support VTL. Haven't been current on free backup wares for a while. One thing to bear in mind as well once you write this 24Tb to a collection of media any single media failure will result in all data being unrecoverable. So you might opt for doubling your backup window and making a duplicate copy. Otherwise your best bet is to put all the drives in a NAS configuration (think FreeNAS) with a RAID6 structure, then have the backup s/w use this as its destination. You could do this with an 8 drive chassis of 8x4Tb SATA disks (2 lost for RAID6, leaves 6x4TB=24Tb raw). A similar idea could be accomplished with ZFS, but its future is somewhat unknown with Oracle these days. If you need longevity, I'd stick with a more open/compatibly filesystem. If you manage to setup it correctly and use exFAT, you could mount the backup volume to any current Linux, Windows, or Mac system and if the backup s/w runs on all platforms you'd have a lot more compatibility and recovery options.