Hi, Currently we have different resync behaviors in array creation. - raid1: copy data from disk 0 to disk 1 (overwrite) - raid10: read both disks, compare and write if there is difference (compare-write) - raid4/5: read first n-1 disks, calculate parity and then write parity to the last disk (overwrite) - raid6: read all disks, calculate parity and compare, and write if there is difference (compare-write) Write whole disk is very unfriendly for SSD, because it reduces lifetime. And if user already does a trim before creation, the unncessary write could make SSD slower in the future. Could we prefer compare-write to overwrite if mdadm detects the disks are SSD? Surely sometimes compare-write is slower than overwrite, so maybe add new option in mdadm. An option to let mdadm trim SSD before creation sounds reasonable too. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
