CentOS-How to add a new disk into a mdadm raid5/dev/md0 whick lost A/DEV/SDC1 disk and revoery at another m Achine?
Fdisk-l--stop/dev/md0
# to force active the raid by Remaind 3 disks. -A--force/dev/md0/dev/sdb1/dev/sde1/dev/sdd1
# Add a new disk into/dev/md0--manage/dev/md0--add/dev/sdc1
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We build a/dev/md0 on a Unitek (removeable USB Storadge with 4 disks inside) by Mdadm software, and mdadm-create/dev/ MD0 operated on a HUAWEI server, our recovery work is done on my laptop, and we meet many many problems, during recovery.
We miss a disk--/DEV/SDC1 from the raid/dev/md0, and now has a new disk--same compable with the LOST/DEV/SBC1, on Ha nd.
And then we Joury is startiing
ll/dev/
Nothing about/dev/md0.
Cat/proc/mdstat
<none>
... nothing (for the totally new machine to the/dev/md0 no conf file, no superblock ...)
- We try force Mdadm to assembly to force Mdadm Auto Recovery itself:
mdadm --assemble--run --force/dev/md0
Mdadm-a--FORCE/DEV/MD0/DEV/SDB1/DEV/SDE1/DEV/SDD1
We get "can ' t open/dev/md0 array info" or "/DEV/SDB1 is busying" and many other error response info;
- Then we try to add a new disk into
Mdadm--manage/dev/md0--add/dev/info for/dev/md0
- Try get into manage mode, can ' t get config file
[Email protected] dev]# mdadm--assemble/dev/md0--scan--force
Mdadm:/dev/md0 not identified in config file.
- A key operated is coming, and leads us to a success result.
All the steps above, we don't stop the/dev/md0 and get many wrong try and get many failed resulte.
Mdadm--stop/dev/md0
Mdadm:stopped/dev/md0
[Email protected] dev]# mdadm--assemble/dev/md0--scan--infilecat / proc/<none>
Mdadm--force start by remain 3 disks, and add a new disk into/dev/md0, and get to recovery state.
[Email protected] dev]#mdadm-a--force/dev/md0/dev/sdb1/dev/sde1/dev/ sdd1mdadm:/dev/md0 have been started with3Drives (out of4). [Email protected] dev]# mdadm --manage/dev/md0--add/dev/ sdc1 mdadm:added/dev/Sdc1[[email protected] dev]#Cat/proc/mdstat personalities: [RAID6] [RAID5] [raid4] md0:active RAID5 sdc1[5] Sdd1[0] Sde1[4] Sdb1[2] 8790402048Blocks Super1.2Level5, 512k Chunk, algorithm2[4/3] [U_uu] [...............] Recovery =0.0% (184776/2930134016) finish=1321.3min speed=36955k/sec Bitmap:0/ Apages [0KB], 65536KB chunkunused devices:<none>
Conclusion:
- Remember to stop/dev/md0 at first step, then do other operates;
- MDADM Create RAID5 array, every RAID array info were storaged at every physical disk, no matter what their position was Ch Anged, Madadm can recognize the correct RAID array info.
- Mdadm is realy a stronger sofeware at protect our data, if use correctly we need not worry on our data ' s safety---if Only lost one disk, we can find them back;
-----Other Relate Info reference
1. http://blog.csdn.net/waityoualife/article/details/5612243
Mdadm raid5/dev/md0 lost a disk and recovery from another machine