Removing one drive from a RAID 1 setup?

Adam Hough adam at gradientzero.com
Thu Aug 27 00:10:04 UTC 2009


On Wed, Aug 26, 2009 at 5:55 PM, Philip Rhoades<phil at pricom.com.au> wrote:
> People,
>
>
> Mick wrote:
>>
>> --- On Tue, 8/25/09, Bruno Wolff III <br... at wolff.to> wrote:
>>>
>>>  Philip Rhoades <p... at pricom.com.au>
>>> wrote:
>>> >
>>> > If I remove this drive, is it straightforward to
>>> continue using the
>>> > remaining drive (sdd) with it's normal ext3 partition
>>> and the data still
>>> > intact?
>>>
>>> It might mess up grub. But otherwise it should work.
>>>
>>
>> I kind of did this.
>>
>> I installed F11 to a raid-1 two sata drives.
>> I could not get it to boot, it wanted a BIOS ID.
>> My BIOS (MSI K9A2) lets me boot from raid, but it does not show up in the
>> first
>> screen.
>> The one with IDE/SATA drives shown.
>>
>> Anyway I went into the BIOS and deleted the raid array.
>> When I tried to install F11 the drives were NOT detected by anaconda.
>>
>> It seems that there are "ghost" dm partitions on them.
>> Anaconda sees them and dies.
>>
>> I was able to install F10 and Mint, as well as XPx64, but not F11 or
>> F12-alpha.
>>
>> Apparently this is a known bug in anaconda.
>>
>> So you may be able to fix up your drive and boot it, you most likely will
>> not
>> be able to install to it.
>>
>> Mick M.
>
>
> Sorry, I should have made it clear sdc & sdd RAID 1 drives are mounted on
> /home, the MBR etc is on sda (/) - but all the extra info was
> interesting/useful anyway!
>
> Thanks,
>
> Phil.
> --
> Philip Rhoades
>

Is sda and sdb a mirror as well? or do you just care about  /home?

If sda and sdb and if /boot is a mirrorred across the two drives then
you need to in most cases hand edit grub so that it will boot from
both drives.

This is a very good right up on how to make a bootable mirrored pair
of drives: http://grub.enbug.org/MirroringRAID.

Also though I have not done a lot of benchmarking, you might want to
consider moving to MD RAID10 instead of RAID1 as i am assuming that
your are using the linux software raid.  The MD RAID10 has the
advantage of striping reads across the 2 drives, while RAID1 does its
read in parallel.
http://en.wikipedia.org/wiki/RAID
http://en.wikipedia.org/wiki/Non-standard_RAID_levels#Linux_MD_RAID_10




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