Software Raid - changed devices


 
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# 1  
Old 10-14-2004
Software Raid - changed devices

Good Morning all,

I just have a quick question, on some systems I am working with Software Raid Level 0 devices.

Yes, I know, this is not a good idea, but it was requested :-(

Now, due to a new requirement, I need to add a second internal disk to the system, but with adding the new disk, all device links of the external disks, /dev/sdg ..., will move one step further.
I tried this on a test system, modified the /etc/raidtab and when I started the raid device, I got the error message that not all devices were aviable.
I check a bit the configuration and the raid configuration itself looks like it is also written to the Superblock of each physical raid device.... and not only to /etc/raidtab ?

Now, I am lookig for a decent solution how to change the raid configuration, I could recreat the raid system after backing up the data, but this I would like to avoid because of time which is needed for it.
I also could fix the counting order of the currently used disk, so the new added disk would start behind the last currently used disk, but this is some kind of special hack, I also would like to avoid ...


Any ideas ?

Btw, I am running RedHat AS 2.1 on a multiprozessor system.

Thnx in advance

Malcom
# 2  
Old 11-12-2004
I recommend using mdadm. An altertive of raidtool.
http://freshmeat.net/projects/mdadm/

Usually raid disks appears as /dev/mdX, not sdX. (At least udev generates mdX).

With mdadm, you can create a new raid disk easily. A quick reference can be found here. http://www.linuxdevcenter.com/pub/a/...2/05/RAID.html

But I think you have to backup data first. Not sure though.
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