Re: please help - raid 1 degraded

[Adam Goryachev <mailinglists@websitemanagers.com.au>]

On 12/02/15 11:09, sunruh@prismnet.com wrote:
> On Thu, Feb 12, 2015 at 09:12:50AM +1100, Adam Goryachev wrote:
>> On 12/02/15 05:04, sunruh@prismnet.com wrote:
>>> centos 6.6
>>> 2x 240gig ssd in raid1
>>> this is a live running production machine and the raid1 is for /u of
>>> users home dirs.
>>>
>>> 1 ssd went totally offline and i replaced it after noticing the firmware
>>> levels are not the same.  the new ssd has the same level firmware.
>>>
>>> /dev/sdb is the good ssd
>>> /dev/sdc is the new blank ssd
>>>
>>> when working it was /u1 from /dev/md127p1 and /u2 from /dev/md127p2
>>> p1 is 80gig and p2 is 160gig for the full 240gig size of the ssd
>>>
>>>> ls -al /dev/md*
>>> brw-rw---- 1 root disk   9, 127 Feb 11 11:09 /dev/md127
>>> brw-rw---- 1 root disk 259,   0 Feb 10 20:23 /dev/md127p1
>>> brw-rw---- 1 root disk 259,   1 Feb 10 20:23 /dev/md127p2
>>>
>>> /dev/md:
>>> total 8
>>> drwxr-xr-x  2 root root  140 Feb 10 20:24 .
>>> drwxr-xr-x 20 root root 3980 Feb 10 20:24 ..
>>> lrwxrwxrwx  1 root root    8 Feb 11 11:09 240ssd_0 -> ../md127
>>> lrwxrwxrwx  1 root root   10 Feb 10 20:23 240ssd_0p1 -> ../md127p1
>>> lrwxrwxrwx  1 root root   10 Feb 10 20:23 240ssd_0p2 -> ../md127p2
>>> -rw-r--r--  1 root root    5 Feb 10 20:24 autorebuild.pid
>>> -rw-------  1 root root   63 Feb 10 20:23 md-device-map
>>>
>>>> ps -eaf | grep mdadm
>>> root      2188     1  0 Feb10 ?        00:00:00 mdadm --monitor --scan -f --pid-file=/var/run/mdadm/mdadm.pid
>>>
>>> how do i rebuild /dev/sdc into the mirror of /dev/sdb?
>>>
>> Please send the output of fdisk -lu /dev/sd[bc] and cat /proc/mdstat
>> (preferably both when it was working and current).
>>
>> In general, when replacing a failed RAID1 disk, and assuming you
>> configured it the way I think you did:
>> 1) fdisk -lu /dev/sdb
>> Find out the exact partition sizes
>> 2) fdisk /dev/sdc
>> Create the new partitions exactly the same as /dev/sdb
>> 3) mdadm --manage /dev/md127 --add /dev/sdb1
>> Add the partition to the array
>> 4) cat /proc/mdstat
>> Watch the rebuild progress, once it is complete, relax.
>>
>> PS, steps 1 and 2 may not be needed if you are using the full block
>> device instead of a partition. Also, change the command in step 3 to
>> "mdadm --manage /dev/md127 --add /dev/sdb"
>>
>> PPS, if this is a bootable disk, you will probably also need to do
>> something with your boot manager to get that installed onto the new disk
>> as well.
>>
>> Hope this helps, otherwise, please provide more information.
>>
>>
>> Regards,
>> Adam
>>
>> -- 
>> Adam Goryachev Website Managers www.websitemanagers.com.au
> Adam (and anybody else that can help),
> after issue i do not have before. and no they are not bootable.
>
> [root@shell ~]# fdisk -lu /dev/sd[bc]
>
> Disk /dev/sdb: 240.1 GB, 240057409536 bytes
> 255 heads, 63 sectors/track, 29185 cylinders, total 468862128 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x0001a740
>
>
> Disk /dev/sdc: 240.1 GB, 240057409536 bytes
> 255 heads, 63 sectors/track, 29185 cylinders, total 468862128 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x00000000
>
> [root@shell ~]# cat /proc/mdstat
> Personalities : [raid1]
> md127 : active raid1 sdb[2]
>        234299840 blocks super 1.2 [2/1] [U_]
>        
> unused devices: <none>

> i dont seem to be seeing the partition sizes or im stupid.
> couldnt i just dd if=/dev/sdb of=/dev/sdc bs=1G count=240 and then do the
> mdadm?
OK, so you aren't using partitioned disks, so it is as simple as what I 
said above (with one minor correction):

"mdadm --manage /dev/md127 --add /dev/sdc"


/dev/sdc is the new blank ssd, so that is the one to add, the above 
command with /dev/sdb wouldn't have done anything at all .... So just 
run that command, and then do "watch cat /proc/mdstat" until the good 
stuff is completed.

Regards,
Adam

-- 
Adam Goryachev Website Managers www.websitemanagers.com.au