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Q: how to re-assemble RAID5 array
After some stupid action (described here) I lost a RAID5 volume (4 x 6TB, OS 4.2.27). The partitions vanished from the partition table. No warranty, no backup. It would be nice (though not essential)...
I guess the SMART stats are OK, the disks have been 'on power' for only about 300 hours (bought them in the beginning of August). Last time I looked at SMART data (via OS6 interface) was around 170 hours, no errors then.
How would I force the array online?
Data recovery by Netgear is not an option I guess (fiddled aroud too much (OS4<->OS6), plus the Pro they were in was not bought new).
Next to that, the data is not that valuable (missing it would be an inconvenience, but not a real problem).
I don't have the spare space to clone about 16 TB. And my girlfriend won't make me live to the end of the weekend if I spend another 1000 EURO's for new disks ... :smileyfrustrated:
So I'll take the chances losing the data.
The disks are now in a Pro6 running Knoppix.
The requested output:
root@Microknoppix:/home/knoppix# cat /proc/partitions major minor #blocks name 240 0 10559232 cloop0 252 0 2259732 zram0 8 0 5860522584 sda 8 1 4193272 sda1 8 2 524228 sda2 8 3 5855800708 sda3 8 16 5860522584 sdb 8 17 4193272 sdb1 8 18 524228 sdb2 8 19 5855800708 sdb3 8 32 5860522584 sdc 8 33 4193272 sdc1 8 34 524228 sdc2 8 35 5855800708 sdc3 8 48 5860522584 sdd 8 49 4193272 sdd1 8 50 524228 sdd2 8 51 5855800708 sdd3 8 80 122368 sdf 8 81 122250 sdf1 8 64 7566624 sde 8 65 4556800 sde1 8 66 3008512 sde2
sda,b,c,d are HDD's,
sde is Knoppix pendrive
sdf is internal flash (I presume)
root@Microknoppix:/home/knoppix# for i in /dev/sd[a-z]; do echo $i; smartctl -a $i | egrep "Model|Firm|Sector|Hours|Error|Uncorr"; done;
/dev/sda
Device Model: WDC WD60EFRX-68MYMN1
Firmware Version: 82.00A82
Sector Sizes: 512 bytes logical, 4096 bytes physical
Error logging capability: (0x01) Error logging supported.
SCT Error Recovery Control supported.
1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0
5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0
7 Seek_Error_Rate 0x002e 100 253 000 Old_age Always - 0
9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 288
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 253 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x0008 100 253 000 Old_age Offline - 0
SMART Error Log Version: 1
No Errors Logged
/dev/sdb
Device Model: WDC WD60EFRX-68MYMN1
Firmware Version: 82.00A82
Sector Sizes: 512 bytes logical, 4096 bytes physical
Error logging capability: (0x01) Error logging supported.
SCT Error Recovery Control supported.
1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0
5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0
7 Seek_Error_Rate 0x002e 100 253 000 Old_age Always - 0
9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 288
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 253 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x0008 100 253 000 Old_age Offline - 0
SMART Error Log Version: 1
No Errors Logged
/dev/sdc
Device Model: WDC WD60EFRX-68MYMN1
Firmware Version: 82.00A82
Sector Sizes: 512 bytes logical, 4096 bytes physical
Error logging capability: (0x01) Error logging supported.
SCT Error Recovery Control supported.
1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0
5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0
7 Seek_Error_Rate 0x002e 100 253 000 Old_age Always - 0
9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 288
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 253 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x0008 100 253 000 Old_age Offline - 0
SMART Error Log Version: 1
No Errors Logged
/dev/sdd
Device Model: WDC WD60EFRX-68MYMN1
Firmware Version: 82.00A82
Sector Sizes: 512 bytes logical, 4096 bytes physical
Error logging capability: (0x01) Error logging supported.
SCT Error Recovery Control supported.
1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0
5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0
7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0
9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 294
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 253 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x0008 100 253 000 Old_age Offline - 0
SMART Error Log Version: 1
No Errors Logged
/dev/sde
/dev/sdf
/dev/sdg
/dev/sdh
If it is OS6 then it would be /dev/md127 not /dev/md2
Does it make any difference if you try to assemble md127 rather than md2?
Best to leave forcing it online as a last resort.
No difference, unfortunately...:
root@Microknoppix:/home/knoppix# mdadm --assemble /dev/md127 --verbose /dev/sd[abcd]3 mdadm: looking for devices for /dev/md127 mdadm: /dev/sda3 is identified as a member of /dev/md127, slot 0. mdadm: /dev/sdb3 is identified as a member of /dev/md127, slot 1. mdadm: /dev/sdc3 is identified as a member of /dev/md127, slot 2. mdadm: /dev/sdd3 is identified as a member of /dev/md127, slot 3. mdadm: failed to add /dev/sdb3 to /dev/md127: Invalid argument mdadm: failed to add /dev/sdc3 to /dev/md127: Invalid argument mdadm: failed to add /dev/sdd3 to /dev/md127: Invalid argument mdadm: failed to add /dev/sda3 to /dev/md127: Invalid argument mdadm: /dev/md127 assembled from 0 drives - need all 4 to start it (use --run to insist).
The array was created with OS4, but there was the stupidity with the switching as described in the post I referenced in the TS, which caused parts of OS6 landing on the OS4 partition.
Therefore I'd rather not put it back on Readynas OS (4 / 6), because I don't trust what drama will happen (and it probably won't boot anyway).
Bur the array was created in OS4.
In addition, I ran a SMART extended offline test last night (took about 12 hours) on all 4 drives. No errors reported whatsoever.
Somehow I can't edit previous posts... :(
From what I gathered around (here and here, amongst others), I think there are 2 options left:
- assembling the array with force:
mdadm --assemble /dev/md2 /dev/sd[abcd]3 --force
or if that won't do it,
-recreating it with one missing disk (to prevent a reconstruction):
mdadm --create /dev/md2 --assume-clean /dev/sd[abc]3 missing
in which case sdd3 wil be left out.
I suspect even the forced assemble will not work, as I (with limited knowledge) see no reason why the non-forced assembling doesn't work, as the RAID events have exactly the same value (99) on all disks.
I'm therefore open to suggestions from more experienced RAID builders ;)
I know I and only I am responsible for whatever consequences, I won't hold anyone (nor Netgear) responsible for what happens or when the array goes exit. I'm just looking for advice and experience from users more experienced than I am.
One thing I did notice: in a 'regular Netgear' setup, there are symbolic links (system running 4.2.27):
root servixa ~ # ll /dev/md* brw-rw---- 1 root disk 9, 0 2014-11-30 02:30 /dev/md0 brw-rw---- 1 root disk 9, 1 2014-11-30 02:30 /dev/md1 brw-rw---- 1 root disk 9, 2 2014-11-30 02:30 /dev/md2 brw-rw---- 1 root disk 9, 3 2014-11-30 02:30 /dev/md3 /dev/md: total 0 drwx------ 2 root root 120 2014-11-30 02:30 . drwxr-xr-x 17 root root 5560 2015-08-23 20:27 .. lrwxrwxrwx 1 root root 6 2014-11-30 02:30 0 -> ../md0 lrwxrwxrwx 1 root root 6 2014-11-30 02:30 1 -> ../md1 lrwxrwxrwx 1 root root 6 2014-11-30 02:30 2 -> ../md2 lrwxrwxrwx 1 root root 6 2014-11-30 02:30 3 -> ../md3
/dev/md/0 is linked to /dev/md0 etc.
In the Knoppix system where the 'broken' array is now, those links aren't there:
root@Microknoppix:/home/knoppix# ll /dev/md* brw-rw---- 1 root disk 9, 0 Aug 30 00:45 /dev/md0 brw-rw---- 1 root disk 9, 127 Aug 30 00:45 /dev/md127 brw-rw---- 1 root disk 9, 2 Aug 29 21:35 /dev/md2
Could that have something to do with the cause, or are those links made by the system after a succesful assemble?
(so are they a cause or a consequence)
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