Raid 5 where 2 disks out of 4 were unplugged

[Gennaro Oliva <gennaro.oliva@gmail.com>]

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mdadm: added /dev/sdc3 to /dev/md1 as 2 (possibly out of date)
mdadm: added /dev/sdd3 to /dev/md1 as 3 (possibly out of date)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