Changing partition types safe? raidtools to mdadm migration

Changing partition types safe? raidtools to mdadm migration

[Simon Matthews]

I have a working RAID1 set. This is in a Gentoo system and I
configured the RAID set using raidtools. I see that Raidtools are now
deprecated in favor of mdadm.

I installed mdadm, but it does not recognize my raid set. I tried the
following command (note that my RAID set is active while I do this):
$   mdadm /dev/md0 --query --detail

This results in no output.  I believe this is because I forgot to
change the partition types on the partitions that make up the RAID set
(/dev/sda1 and /dev/sdb1) to type fd (they are the default type 82).

Can I safely change the partition types to fd on the partions that
make up my RAID set?

Or is there something else I should do to get mdadm to recognize my RAID set?

Regards,
Simon

Re: Changing partition types safe? raidtools to mdadm migration

[Neil Brown]

On Thursday March 8, simon.d.matthews@gmail.com wrote:
> I have a working RAID1 set. This is in a Gentoo system and I
> configured the RAID set using raidtools. I see that Raidtools are now
> deprecated in favor of mdadm.
> 
> I installed mdadm, but it does not recognize my raid set. I tried the
> following command (note that my RAID set is active while I do this):
> $   mdadm /dev/md0 --query --detail

Try
  mdadm --detail /dev/md0

If that doesn't work, what about
  cat /proc/mdadm

> 
> This results in no output.  I believe this is because I forgot to
> change the partition types on the partitions that make up the RAID set
> (/dev/sda1 and /dev/sdb1) to type fd (they are the default type 82).

It has nothing to do with partition types.

> 
> Can I safely change the partition types to fd on the partions that
> make up my RAID set?

It is perfectly safe to change partition type.

NeilBrown

Re: Changing partition types safe? raidtools to mdadm migration

[Simon Matthews]

Neil,


On 3/8/07, Neil Brown <neilb@suse.de> wrote:
> On Thursday March 8, simon.d.matthews@gmail.com wrote:
> > I have a working RAID1 set. This is in a Gentoo system and I
> > configured the RAID set using raidtools. I see that Raidtools are now
> > deprecated in favor of mdadm.
> >
> > I installed mdadm, but it does not recognize my raid set. I tried the
> > following command (note that my RAID set is active while I do this):
> > $   mdadm /dev/md0 --query --detail
>
> Try
>   mdadm --detail /dev/md0

Looks good:

# mdadm --detail /dev/md0
/dev/md0:
        Version : 00.90.03
  Creation Time : Sat Oct 15 16:20:52 2005
     Raid Level : raid1
     Array Size : 198153664 (188.97 GiB 202.91 GB)
  Used Dev Size : 198153664 (188.97 GiB 202.91 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Thu Mar  8 23:15:38 2007
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : de2ca4d0:7a3f6d57:d6751dc4:a51265e3
         Events : 0.12491522

    Number   Major   Minor   RaidDevice State
       0       8       18        0      active sync   /dev/sdb2



>
> If that doesn't work, what about
>   cat /proc/mdadm
>
> >
> > This results in no output.  I believe this is because I forgot to
> > change the partition types on the partitions that make up the RAID set
> > (/dev/sda1 and /dev/sdb1) to type fd (they are the default type 82).
>
> It has nothing to do with partition types.
>
> >
> > Can I safely change the partition types to fd on the partions that
> > make up my RAID set?
>
> It is perfectly safe to change partition type.

So I should be safe in just removing the raidtools package and
installing mdadm?

Regards,
Simon

Re: Changing partition types safe? raidtools to mdadm migration

[Simon Matthews]

Neil,



On 3/8/07, Simon Matthews <simon.d.matthews@gmail.com> wrote:
>     Number   Major   Minor   RaidDevice State
>        0       8       18        0      active sync   /dev/sdb2

I missed one line from the above:
       1       8        2        1      active sync   /dev/sda2


Simon

Re: Changing partition types safe? raidtools to mdadm migration

[Neil Brown]

On Thursday March 8, simon.d.matthews@gmail.com wrote:
> 
> So I should be safe in just removing the raidtools package and
> installing mdadm?
> 

Possibly.
A significant difference is the way arrays are assembled at boot time.
raidtools depended on raidstart (which never worked reliably and
doesn't work at all with recent kernels) or type-FD partitions, 
which I assume you weren't using.

mdadm has a lot more flexibility.  You can still use type-FD
partitions if you want, or you create /etc/mdadm.conf with roughly the
output of 
   mdadm -Ds

though it is worth understanding the contents of that file and making
sure it is what you want.

NeilBrown