Re: failed drive in raid 1 array

[Roberto Spadim <roberto@spadim.com.br>]

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


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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-- 
Roberto Spadim
Spadim Technology / SPAEmpresarial
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