Hello, I have a QNAP with Linux 3.4.6 and mdadm 3.3. I have 4 drives assembled in raid 5, two of those drives where accidentally removed and now they are out of sync. This is a partial output of mdadm --examine /dev/sda3: Update Time : Thu Jul 8 18:01:51 2021 Checksum : 4bc8157c - correct Events : 469678 Device Role : Active device 0 Array State : AAA. ('A' == active, '.' == missing, 'R' == replacing) /dev/sdb3: Update Time : Thu Jul 8 18:01:51 2021 Checksum : 7fac997f - correct Events : 469678 Device Role : Active device 1 Array State : AAA. ('A' == active, '.' == missing, 'R' == replacing) /dev/sdc3: Update Time : Thu Jul 8 13:15:58 2021 Checksum : fcd5279f - correct Events : 469667 Device Role : Active device 2 Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing) /dev/sdd3: Update Time : Thu Jul 8 13:15:58 2021 Checksum : b9bc1e2e - correct Events : 469667 Device Role : Active device 3 Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing) The disk are all healthy. I tried to re-assemble the drive with mdadm --verbose --assemble --force using various combination of 3 drives or using all the four drives but I'm always notified I have no enough drives to start the array. This is the output when trying to use all the drives: mdadm --verbose --assemble --force /dev/md1 /dev/sda3 /dev/sdb3 /dev/sdc3 /dev/sdd3 mdadm: looking for devices for /dev/md1 mdadm: failed to get exclusive lock on mapfile - continue anyway... mdadm: /dev/sda3 is identified as a member of /dev/md1, slot 0. mdadm: /dev/sdb3 is identified as a member of /dev/md1, slot 1. mdadm: /dev/sdc3 is identified as a member of /dev/md1, slot 2. mdadm: /dev/sdd3 is identified as a member of /dev/md1, slot 3. mdadm: added /dev/sdb3 to /dev/md1 as 1 mdadm: added /dev/sdc3 to /dev/md1 as 2 (possibly out of date) mdadm: added /dev/sdd3 to /dev/md1 as 3 (possibly out of date) mdadm: added /dev/sda3 to /dev/md1 as 0 mdadm: /dev/md1 assembled from 2 drives - not enough to start the array. The number of events is really close (11). What is my next option to recover the partition? Do I need to rebuild the superblock? What options should I use? Thank you for reading this e-mail. Best regards, -- Gennaro Oliva