Je mets ci-dessous toute la procédure effectuée via telnet...
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DiskStation> sfdisk -l
Disk /dev/sda: 182401 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sda1 0+ 309 310- 2490043+ fd Linux raid autodetect
/dev/sda2 310 374 65 522112+ fd Linux raid autodetect
/dev/sda3 391 182400 182010 1461995325 fd Linux raid autodetect
/dev/sda4 0 - 0 0 0 Empty
Disk /dev/sdb: 182401 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sdb1 0+ 309 310- 2490043+ fd Linux raid autodetect
/dev/sdb2 310 374 65 522112+ fd Linux raid autodetect
/dev/sdb3 391 182400 182010 1461995325 fd Linux raid autodetect
/dev/sdb4 0 - 0 0 0 Empty
Disk /dev/sdd: 182401 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sdd1 0+ 309 310- 2490043+ fd Linux raid autodetect
/dev/sdd2 310 374 65 522112+ fd Linux raid autodetect
/dev/sdd3 391 182400 182010 1461995325 fd Linux raid autodetect
/dev/sdd4 0 - 0 0 0 Empty
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DiskStation> df
Filesystem 1k-blocks Used Available Use% Mounted on
/dev/md0 2450808 403012 1945396 17% /
/tmp 257924 120 257804 0% /tmp
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DiskStation> cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid6] [raid5] [raid4]
md2 : active raid5 sdd3[3]
4385985600 blocks level 5, 64k chunk, algorithm 2 [4/1] [___U]
md1 : active raid1 sda2[0] sdb2[1] sdd2[3]
522048 blocks [4/3] [uU_U]
md0 : active raid1 sda1[0] sdb1[1] sdd1[3]
2489920 blocks [4/3] [uU_U]
unused devices: <none>
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DiskStation> mdadm -S /dev/md2
mdadm: stopped /dev/md2
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DiskStation> mdadm --assemble --force /dev/md2 /dev/sd[abd]3
mdadm: forcing event count in /dev/sda3(0) from 4796 upto 4814
Segmentation fault (core dumped)