Re: failed drive in raid 1 array

[Roberto Nunnari <roberto.nunnari@supsi.ch>]

Roberto Spadim wrote:
> hum, maybe you are using mdadm.conf or autodetect, non autodetect
> should be something like this:
> i don´t know the best solution, but it works ehhehe
> 
>         kernel /vmlinuz-2.6.9-89.31.1.ELsmp ro root=/dev/md0 rhgb
> quiet md=0,/dev/sda,/dev/sdb md=1,xxxx,yyyy.....
> 
> or another md array...
> 
> humm i readed the sata specification and removing isn´t a problem, at
> eletronic level the sata channel is only data, no power source, all
> channels are diferencial (like rs422 or rs485), i don´t see anyproblem
> removing it. i tryed hot plug a revodrive (pciexpress ssd) and it
> don´t work (reboot) hehehe, pci-express isn´t hot plug =P, sata2 don´t
> have problems, the main problem is a short circuit at power source, if
> you remove with caution no problems =)
> 
> i tried in some others distros and udev created a new device when add
> a diferent disk for example, remove sdb, and add another disk create
> sdc (not sdb), maybe with another udev configuration should work

Ok. I'll keep all that in mind tomorrow.
Best regards.
Robi


> 
> 
> 2011/2/23 Roberto Nunnari <roberto.nunnari@supsi.ch>:
>> Roberto Spadim wrote:
>>> i don´t know how you setup your kernel (with or without raid
>> I use the official CentOS kernel with no modification and don't
>> know about raid autodetect, but:
>> # cat /boot/config-2.6.24-28-server |grep -i raid
>> CONFIG_BLK_DEV_3W_XXXX_RAID=m
>> CONFIG_MD_RAID0=m
>> CONFIG_MD_RAID1=m
>> CONFIG_MD_RAID10=m
>> CONFIG_MD_RAID456=m
>> CONFIG_MD_RAID5_RESHAPE=y
>> CONFIG_MEGARAID_LEGACY=m
>> CONFIG_MEGARAID_MAILBOX=m
>> CONFIG_MEGARAID_MM=m
>> CONFIG_MEGARAID_NEWGEN=y
>> CONFIG_MEGARAID_SAS=m
>> CONFIG_RAID_ATTRS=m
>> CONFIG_SCSI_AACRAID=m
>>
>>
>>> autodetect?) do you use kernel command line to setup raid? autodetect?
>> /dev/md0 in grub
>> I don't know if that means autodetect, but I guess so..
>>
>>
>>> here in my test machine i´m using kernel command line (grub), i don´t
>>> have a server with hotplug bay, i open the case and remove the wire
>>> with my hands =) after reconecting it with another device kerenel
>> Is it safe? Isn't it a blind bet to fry up the controller and/or disk?
>>
>>
>>> recognize the new device reread the parititions etc etc and i can add
>>> it to array again
>>> my grub is something like:
>>>
>>> md=0,/dev/sda,/dev/sdb .....
>>>
>>> internal meta data, raid1, i didn´t like the autodetect (it´s good)
>>> but i prefer hardcoded kernel command line (it´s not good with usb
>>> devices)
>> the relevant part of my grub is:
>>
>> default=0
>> timeout=5
>> splashimage=(hd0,0)/grub/splash.xpm.gz
>> hiddenmenu
>> title CentOS (2.6.9-89.31.1.ELsmp)
>>        root (hd0,0)
>>        kernel /vmlinuz-2.6.9-89.31.1.ELsmp ro root=/dev/md0 rhgb quiet
>>        initrd /initrd-2.6.9-89.31.1.ELsmp.img
>>
>> Best regards.
>> Robi
>>
>>
>>> 2011/2/23 Roberto Nunnari <roberto.nunnari@supsi.ch>:
>>>> Roberto Spadim wrote:
>>>>> sata2 without hot plug?
>>>> Hi Roberto.
>>>>
>>>> I mean that there is no hot-plug bay, with sliding rails etc..
>>>> The drives are connected to the mb using standard sata cables.
>>>>
>>>>
>>>>> check if your sda sdb sdc will change after removing it, it愀 depends
>>>>> on your udev or another /dev filesystem
>>>> Ok, thank you.
>>>> That means that if I take care to check the above, and
>>>> the new drive will be sdb, then taking the steps indicated
>>>> in my original post will do the job?
>>>>
>>>> Best regards.
>>>> Robi
>>>>
>>>>
>>>>> 2011/2/23 Roberto Nunnari <roberto.nunnari@supsi.ch>:
>>>>>> Hello.
>>>>>>
>>>>>> I have a linux box, with two 2TB sata HD in raid 1.
>>>>>>
>>>>>> Now, one disk is in failed state and it has no spares:
>>>>>> # cat /proc/mdstat
>>>>>> Personalities : [raid1]
>>>>>> md1 : active raid1 sdb4[2](F) sda4[0]
>>>>>>    1910200704 blocks [2/1] [U_]
>>>>>>
>>>>>> md0 : active raid1 sdb1[1] sda2[0]
>>>>>>    40957568 blocks [2/2] [UU]
>>>>>>
>>>>>> unused devices: <none>
>>>>>>
>>>>>>
>>>>>> The drives are not hot-plug, so I need to shutdown the box.
>>>>>>
>>>>>> My plan is to:
>>>>>> # sfdisk -d /dev/sdb > sdb.sfdisk
>>>>>> # mdadm /dev/md1 -r /dev/sdb4
>>>>>> # mdadm /dev/md0 -r /dev/sdb1
>>>>>> # shutdown -h now
>>>>>>
>>>>>> replace the disk and boot (it should come back up, even without one
>>>>>> drive,
>>>>>> right?)
>>>>>>
>>>>>> # sfdisk /dev/sdb < sdb.sfdisk
>>>>>> # mdadm /dev/md1 -a /dev/sdb4
>>>>>> # mdadm /dev/md0 -a /dev/sdb1
>>>>>>
>>>>>> and the drives should start to resync, right?
>>>>>>
>>>>>> This is my first time I do such a thing, so please, correct me
>>>>>> if the above is not correct, or is not a best practice for
>>>>>> my configuration.
>>>>>>
>>>>>> My last backup of md1 is of mid november, so I need to be
>>>>>> pretty sure I will not lose my data (over 1TB).
>>>>>>
>>>>>> A bit abount my environment:
>>>>>> # mdadm --version
>>>>>> mdadm - v1.12.0 - 14 June 2005
>>>>>> # cat /etc/redhat-release
>>>>>> CentOS release 4.8 (Final)
>>>>>> # uname -rms
>>>>>> Linux 2.6.9-89.31.1.ELsmp i686
>>>>>>
>>>>>> Thank you very much and best regards.
>>>>>> Robi

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