| > it feels like repairing an array takes time proportional to the size of the drive, not the size of the contents This is only true for drive-level raid rather than filesystem level raid, or a non-raid solution like ceph's replication. ZFS's filesystem raid can repair a raid in time proportional to the amount of data stored in it. mdadm and raid controllers aren't aware of which parts of the block device are in use or not, and thus have to repair the whole drive. It's exceedingly likely that backblaze's solution does not require repairing entire block devices, but rather is likely to be closer to ceph, where only the in-use portion of a failed drive must be considered / must find a new home. I think raid and distributed storage systems (like backblaze or ceph) are more different than they are alike. > From the behavior of my RAID (which also uses Reed Solomon, doesn't it?) Maybe. mdadm raid5 doesn't, nor does mdadm raid1 or raid10. I think mdadm's raid6 does. |