&gt; Can it be as simple as a spanning partition to treat all drives as a single drive?<p>Sure, but there are tradeoffs. One option is to just concatenate all the drives together, either with mdadm (grouping the drives into a RAID-0 array) or with LVM (adding them all to a single volume group). This lets you add drives very easily and efficiently, but has no redundancy. When (not if) one drive fails, your entire FS is toast.<p>If you care about your data, then you&#x27;ll want to use RAID-6 for redundancy. But adding a drive to a RAID-6 array is very time-consuming, because all of your data has to be re-shuffled onto a new drive. And you don&#x27;t want to do this without a backup -- although the reshape process is designed to be safely interruptible, it&#x27;s not bug-free. (I speak from experience, having nearly lost a few TB this way not too long ago.)<p>You can compromise by grouping your drives into multiple RAID-6 arrays. For example, instead of using 58 data drives + 2 parity drives, you could use 6 arrays of (8 data + 2 parity). This gives you much less usable space (80% as opposed to 97%) but it allows you to add 10 drives at a time without having to re-shuffle all your data. And it means you can recover from a drive failure much more quickly.<p>Of course, you can also just treat the drives as separate block devices, and provide a single redundant filesystem at a higher level, using something like Ceph. I would assume Backblaze is doing something along these lines.